IB Biology SL Flashcards: Complete Course Review
Review the current IB Biology Standard Level course with 960 independently written active-recall cards covering all 34 SL topics across molecules, cells, organisms, genetics, evolution, and ecology.
حول هذه الرزمة
Study the current IB Biology SL course with 960 independently written English flashcards. The deck covers all 34 Standard Level topics through four broad groups: molecules and cells; metabolism and genetics; organisms and systems; and evolution and ecology.
Cards move from essential terms and structures to functions, mechanisms, comparisons, predictions, and compact interpretation prompts. Useful two-way term cards are separated by at least three unrelated cards, while explanatory answers are kept in the direction that supports meaningful recall. Every card carries the root tag ib-bio-sl and exactly one broad group tag.
The order introduces prerequisite ideas before dependent ones and progresses from simpler recall to more demanding reasoning within each topic. The deck is designed for ongoing spaced review. It does not replace data-heavy practice papers, extended-response practice, laboratory work, or the scientific investigation.
Reviewed in 2026 against the current Biology Standard Level course, first assessed in 2025.
Independent, unofficial study aid based on common biological knowledge. Not affiliated with or endorsed by the International Baccalaureate Organization. No copied IB examination questions, mark schemes, or curriculum text are included.
Check the official IB Biology course page for authoritative requirements.
بطاقات هذه الرزمة
البطاقة ١
السؤال
What is water polarity?
الإجابة
The unequal sharing of electrons in a water molecule, giving oxygen a partial negative charge and the hydrogens partial positive charges.
البطاقة ٢
السؤال
What is a hydrogen bond?
الإجابة
A weak attraction between a partially positive hydrogen atom and a partially negative atom in another molecule.
البطاقة ٣
السؤال
What is cohesion?
الإجابة
Attraction between molecules of the same substance.
البطاقة ٤
السؤال
What is adhesion?
الإجابة
Attraction between molecules of different substances.
البطاقة ٥
السؤال
Which term describes unequal charge distribution within a water molecule?
الإجابة
water polarity
البطاقة ٦
السؤال
Which term describes the intermolecular attraction that links neighboring water molecules?
الإجابة
a hydrogen bond
البطاقة ٧
السؤال
Which term describes attraction between molecules of the same substance?
الإجابة
cohesion
البطاقة ٨
السؤال
Which term describes attraction between water and a different material?
الإجابة
adhesion
البطاقة ٩
السؤال
What is a solvent?
الإجابة
A liquid that dissolves solutes to form a solution.
البطاقة ١٠
السؤال
What is specific heat capacity?
الإجابة
The energy required to raise the temperature of a unit mass of a substance by one degree.
البطاقة ١١
السؤال
What is latent heat of vaporization?
الإجابة
The energy required to vaporize a specified amount of liquid without changing its temperature.
البطاقة ١٢
السؤال
Why does ice float on liquid water?
الإجابة
Hydrogen bonds hold water molecules in an open lattice in ice, making ice less dense than liquid water.
البطاقة ١٣
السؤال
Which term describes a liquid that dissolves solutes?
الإجابة
a solvent
البطاقة ١٤
السؤال
Which term describes the energy needed to raise a unit mass by one degree?
الإجابة
specific heat capacity
البطاقة ١٥
السؤال
Which term describes the energy needed to vaporize a liquid without a temperature change?
الإجابة
latent heat of vaporization
البطاقة ١٦
السؤال
Which property of water makes sweating an effective cooling mechanism?
الإجابة
Water absorbs substantial energy as it evaporates; the highest-energy molecules leave, carrying heat away from the skin.
البطاقة ١٧
السؤال
Why does water resist rapid temperature change?
الإجابة
Many hydrogen bonds must absorb energy before molecular motion increases substantially, giving water a high specific heat capacity.
البطاقة ١٨
السؤال
How do cohesion and adhesion support water transport in narrow tubes?
الإجابة
Cohesion keeps water molecules connected, while adhesion helps the water column cling to the tube wall.
البطاقة ١٩
السؤال
How does water participate differently in hydrolysis and condensation?
الإجابة
Hydrolysis consumes water to split a bond; condensation forms a bond and releases water.
البطاقة ٢٠
السؤال
How does floating ice protect aquatic life in winter?
الإجابة
Surface ice insulates the liquid water below, slowing further heat loss and preventing the whole body of water from freezing rapidly.
البطاقة ٢١
السؤال
Why is water effective for transporting many biological solutes?
الإجابة
Its polarity allows ions and other polar molecules to become surrounded and dispersed in solution.
البطاقة ٢٢
السؤال
Why do nonpolar substances tend to cluster in water?
الإجابة
Clustering reduces the nonpolar surface exposed to water, allowing more water molecules to maintain hydrogen-bond interactions.
البطاقة ٢٣
السؤال
What is a nucleotide?
الإجابة
A nucleic-acid monomer made of a pentose sugar, a phosphate group, and a nitrogenous base.
البطاقة ٢٤
السؤال
What is a nucleoside?
الإجابة
A nitrogenous base joined to a pentose sugar, without a phosphate group.
البطاقة ٢٥
السؤال
What is a phosphodiester bond?
الإجابة
A covalent bond linking the phosphate of one nucleotide to the sugar of the next nucleotide.
البطاقة ٢٦
السؤال
What is DNA?
الإجابة
A usually double-stranded nucleic acid that stores hereditary information in its base sequence.
البطاقة ٢٧
السؤال
Which term describes a sugar-phosphate-base monomer?
الإجابة
a nucleotide
البطاقة ٢٨
السؤال
Which term describes a base joined to a sugar but no phosphate?
الإجابة
a nucleoside
البطاقة ٢٩
السؤال
Which term describes the covalent linkage in a nucleic-acid sugar-phosphate backbone?
الإجابة
a phosphodiester bond
البطاقة ٣٠
السؤال
Which term describes the nucleic acid that usually stores hereditary information?
الإجابة
DNA
البطاقة ٣١
السؤال
What is RNA?
الإجابة
A usually single-stranded nucleic acid involved in expressing and regulating genetic information.
البطاقة ٣٢
السؤال
What are antiparallel DNA strands?
الإجابة
Two DNA strands that run in opposite 5′ to 3′ directions.
البطاقة ٣٣
السؤال
What is complementary base pairing?
الإجابة
Specific pairing in which adenine pairs with thymine in DNA, or uracil in RNA, and cytosine pairs with guanine.
البطاقة ٣٤
السؤال
What is a purine?
الإجابة
A nitrogenous base with two fused rings; adenine and guanine are purines.
البطاقة ٣٥
السؤال
Which term describes the usually single-stranded nucleic acid used in gene expression?
الإجابة
RNA
البطاقة ٣٦
السؤال
Which term describes DNA strands running in opposite directions?
الإجابة
antiparallel DNA strands
البطاقة ٣٧
السؤال
Which term describes specific A–T or A–U and C–G pairing?
الإجابة
complementary base pairing
البطاقة ٣٨
السؤال
Which term describes a two-ring nitrogenous base?
الإجابة
a purine
البطاقة ٣٩
السؤال
What is a pyrimidine?
الإجابة
A nitrogenous base with one ring; cytosine, thymine, and uracil are pyrimidines.
البطاقة ٤٠
السؤال
What is a genome?
الإجابة
The complete genetic material of an organism or cell.
البطاقة ٤١
السؤال
What three structural features commonly distinguish RNA from DNA?
الإجابة
RNA usually contains ribose, uses uracil instead of thymine, and is single-stranded rather than double-stranded.
البطاقة ٤٢
السؤال
What determines the base sequence of the second DNA strand?
الإجابة
Complementary base-pairing rules determine it: A pairs with T, and C pairs with G.
البطاقة ٤٣
السؤال
Which term describes a one-ring nitrogenous base?
الإجابة
a pyrimidine
البطاقة ٤٤
السؤال
Which term describes the complete genetic material of an organism?
الإجابة
a genome
البطاقة ٤٥
السؤال
What do the 5′ and 3′ labels of a nucleic-acid strand refer to?
الإجابة
They refer to numbered carbon atoms in the pentose sugar and define the strand's chemical direction.
البطاقة ٤٦
السؤال
Where is genetic information encoded in DNA?
الإجابة
In the order of nitrogenous bases along the DNA strand.
البطاقة ٤٧
السؤال
Why is ATP classified as a nucleotide?
الإجابة
It contains adenine, ribose, and phosphate groups, the three component types of a nucleotide.
البطاقة ٤٨
السؤال
How do mRNA, tRNA, and rRNA contribute to protein synthesis?
الإجابة
mRNA carries the coding sequence, tRNA delivers amino acids, and rRNA forms the catalytic and structural core of ribosomes.
البطاقة ٤٩
السؤال
How are a gene and a chromosome related?
الإجابة
A gene is a DNA sequence with a biological function; a chromosome is one long DNA molecule containing many genes and other sequences.
البطاقة ٥٠
السؤال
What happens to double-stranded DNA when it is denatured by heat?
الإجابة
Hydrogen bonds between complementary bases break and the two strands separate; the covalent backbones usually remain intact.
البطاقة ٥١
السؤال
Why can each DNA strand serve as a template during replication?
الإجابة
Its base sequence determines a complementary sequence through specific base pairing.
البطاقة ٥٢
السؤال
In which direction are new nucleic-acid strands synthesized?
الإجابة
Nucleotides are added to the 3′ end, so synthesis proceeds 5′ to 3′.
البطاقة ٥٣
السؤال
What is a monosaccharide?
الإجابة
A single sugar unit that can serve as a carbohydrate monomer.
البطاقة ٥٤
السؤال
What is a disaccharide?
الإجابة
A carbohydrate formed from two monosaccharides joined by a glycosidic bond.
البطاقة ٥٥
السؤال
What is a polysaccharide?
الإجابة
A polymer made from many monosaccharide units.
البطاقة ٥٦
السؤال
What is a glycosidic bond?
الإجابة
A covalent bond joining monosaccharides in a carbohydrate.
البطاقة ٥٧
السؤال
Which term describes a single sugar unit?
الإجابة
a monosaccharide
البطاقة ٥٨
السؤال
Which term describes two monosaccharides joined together?
الإجابة
a disaccharide
البطاقة ٥٩
السؤال
Which term describes a polymer of many sugar units?
الإجابة
a polysaccharide
البطاقة ٦٠
السؤال
Which term describes the covalent linkage between monosaccharides?
الإجابة
a glycosidic bond
البطاقة ٦١
السؤال
What is a triglyceride?
الإجابة
A lipid formed from glycerol joined to three fatty acids.
البطاقة ٦٢
السؤال
What is a fatty acid?
الإجابة
A hydrocarbon chain with a carboxyl group that can form part of many lipids.
البطاقة ٦٣
السؤال
What is a saturated fatty acid?
الإجابة
A fatty acid with no carbon-carbon double bonds in its hydrocarbon chain.
البطاقة ٦٤
السؤال
What is a phospholipid?
الإجابة
An amphipathic lipid with a phosphate-containing hydrophilic head and hydrophobic fatty-acid tails.
البطاقة ٦٥
السؤال
Which term describes glycerol joined to three fatty acids?
الإجابة
a triglyceride
البطاقة ٦٦
السؤال
Which term describes a hydrocarbon chain ending in a carboxyl group?
الإجابة
a fatty acid
البطاقة ٦٧
السؤال
Which term describes a fatty acid without carbon-carbon double bonds?
الإجابة
a saturated fatty acid
البطاقة ٦٨
السؤال
Which term describes a lipid with a polar head and nonpolar tails?
الإجابة
a phospholipid
البطاقة ٦٩
السؤال
How is a glycosidic bond formed between two monosaccharides?
الإجابة
A condensation reaction joins them and releases a molecule of water.
البطاقة ٧٠
السؤال
How is a polysaccharide broken into smaller sugars?
الإجابة
Hydrolysis adds water across glycosidic bonds, splitting the polymer.
البطاقة ٧١
السؤال
Which polysaccharides store glucose in plants and animals?
الإجابة
Starch stores glucose in plants; glycogen stores glucose in animals and fungi.
البطاقة ٧٢
السؤال
Why is cellulose suitable for plant cell walls?
الإجابة
Its straight β-glucose chains hydrogen-bond into strong microfibrils that resist stretching.
البطاقة ٧٣
السؤال
Why do lipids store more energy per gram than carbohydrates?
الإجابة
Lipids contain more energy-rich carbon-hydrogen bonds and are more reduced.
البطاقة ٧٤
السؤال
Why do phospholipids form bilayers in water?
الإجابة
Hydrophilic heads interact with water while hydrophobic tails cluster away from water.
البطاقة ٧٥
السؤال
Besides energy storage, what are three biological roles of lipids?
الإجابة
They form membranes, provide thermal insulation and cushioning, and can act as signaling molecules.
البطاقة ٧٦
السؤال
How do cis double bonds affect fatty-acid packing and melting point?
الإجابة
They introduce bends that reduce close packing, usually lowering the melting point.
البطاقة ٧٧
السؤال
What is an amino acid?
الإجابة
A protein monomer with an amino group, a carboxyl group, a hydrogen, and a variable R group attached to a central carbon.
البطاقة ٧٨
السؤال
What is a peptide bond?
الإجابة
The covalent bond formed between the amino group of one amino acid and the carboxyl group of another.
البطاقة ٧٩
السؤال
What is a polypeptide?
الإجابة
A chain of amino acids joined by peptide bonds.
البطاقة ٨٠
السؤال
What is protein primary structure?
الإجابة
The amino-acid sequence of a polypeptide.
البطاقة ٨١
السؤال
Which term describes a protein monomer with amino, carboxyl, and variable R groups?
الإجابة
an amino acid
البطاقة ٨٢
السؤال
Which term describes the covalent linkage between amino acids?
الإجابة
a peptide bond
البطاقة ٨٣
السؤال
Which term describes a chain of peptide-linked amino acids?
الإجابة
a polypeptide
البطاقة ٨٤
السؤال
Which term describes a protein's amino-acid sequence?
الإجابة
protein primary structure
البطاقة ٨٥
السؤال
What is protein secondary structure?
الإجابة
Local folding such as α-helices and β-sheets stabilized mainly by backbone hydrogen bonds.
البطاقة ٨٦
السؤال
What is protein tertiary structure?
الإجابة
The overall three-dimensional shape of one polypeptide produced by interactions among R groups and the backbone.
البطاقة ٨٧
السؤال
What is protein quaternary structure?
الإجابة
The arrangement of multiple polypeptide subunits in one functional protein.
البطاقة ٨٨
السؤال
What is protein denaturation?
الإجابة
Loss of a protein's normal three-dimensional shape and therefore usually its function.
البطاقة ٨٩
السؤال
Which term describes local α-helix and β-sheet folding?
الإجابة
protein secondary structure
البطاقة ٩٠
السؤال
Which term describes the overall three-dimensional shape of one polypeptide?
الإجابة
protein tertiary structure
البطاقة ٩١
السؤال
Which term describes the association of multiple polypeptide subunits?
الإجابة
protein quaternary structure
البطاقة ٩٢
السؤال
Which term describes loss of a protein's native shape?
الإجابة
protein denaturation
البطاقة ٩٣
السؤال
What mainly gives different amino acids their different chemical properties?
الإجابة
Their variable R groups.
البطاقة ٩٤
السؤال
What reaction forms a peptide bond?
الإجابة
A condensation reaction releases water as the amino and carboxyl groups join.
البطاقة ٩٥
السؤال
Why can high temperature denature a protein?
الإجابة
Increased molecular motion disrupts weak interactions that maintain the protein's shape.
البطاقة ٩٦
السؤال
Why can extreme pH denature a protein?
الإجابة
It changes the charges of R groups and disrupts ionic and hydrogen-bond interactions.
البطاقة ٩٧
السؤال
How do fibrous and globular proteins generally differ?
الإجابة
Fibrous proteins are elongated and mainly structural; globular proteins are compact and often perform dynamic functions.
البطاقة ٩٨
السؤال
Why is three-dimensional shape crucial to protein function?
الإجابة
It creates specific binding, catalytic, structural, or interaction surfaces.
البطاقة ٩٩
السؤال
Name four broad biological roles of proteins.
الإجابة
Catalysis, transport, signaling, defense, movement, and structural support are major roles; any four are sufficient.
البطاقة ١٠٠
السؤال
How can changing one amino acid alter protein function?
الإجابة
The substitution can change R-group interactions, folding, stability, or an active or binding site.
البطاقة ١٠١
السؤال
What is cell theory?
الإجابة
The principles that living organisms are made of cells, cells are the basic units of life, and cells arise from pre-existing cells.
البطاقة ١٠٢
السؤال
What is a prokaryotic cell?
الإجابة
A cell without a nucleus or other membrane-bound organelles.
البطاقة ١٠٣
السؤال
What is a eukaryotic cell?
الإجابة
A cell with DNA enclosed in a nucleus and with membrane-bound organelles.
البطاقة ١٠٤
السؤال
What is the nucleus?
الإجابة
The double-membrane organelle that contains most of a eukaryotic cell's DNA.
البطاقة ١٠٥
السؤال
Which term describes the principles describing cells as life's basic units?
الإجابة
cell theory
البطاقة ١٠٦
السؤال
Which term describes a cell lacking a nucleus and membrane-bound organelles?
الإجابة
a prokaryotic cell
البطاقة ١٠٧
السؤال
Which term describes a cell with a nucleus and membrane-bound organelles?
الإجابة
a eukaryotic cell
البطاقة ١٠٨
السؤال
Which term describes the organelle containing most eukaryotic DNA?
الإجابة
the nucleus
البطاقة ١٠٩
السؤال
What is a ribosome?
الإجابة
A molecular complex of rRNA and proteins that synthesizes polypeptides.
البطاقة ١١٠
السؤال
What is the cytoplasm?
الإجابة
The material inside the plasma membrane but outside the nucleus, including cytosol and organelles.
البطاقة ١١١
السؤال
What is the plasma membrane?
الإجابة
The selectively permeable boundary separating a cell from its environment.
البطاقة ١١٢
السؤال
What is a cell wall?
الإجابة
A rigid extracellular layer that supports and protects cells in plants, fungi, and most prokaryotes.
البطاقة ١١٣
السؤال
Which term describes the complex that synthesizes polypeptides?
الإجابة
a ribosome
البطاقة ١١٤
السؤال
Which term describes cell contents inside the plasma membrane but outside the nucleus?
الإجابة
the cytoplasm
البطاقة ١١٥
السؤال
Which term describes the selectively permeable cell boundary?
الإجابة
the plasma membrane
البطاقة ١١٦
السؤال
Which term describes a rigid extracellular support layer?
الإجابة
a cell wall
البطاقة ١١٧
السؤال
What is the nucleoid?
الإجابة
The non-membrane-bound region containing the main chromosome of a prokaryotic cell.
البطاقة ١١٨
السؤال
What is the cytoskeleton?
الإجابة
A dynamic network of protein filaments involved in cell shape, transport, division, and movement.
البطاقة ١١٩
السؤال
What structures are shared by all cells?
الإجابة
A plasma membrane, cytoplasm, genetic material, and ribosomes.
البطاقة ١٢٠
السؤال
Which structures distinguish a typical plant cell from a typical animal cell?
الإجابة
A plant cell has a cellulose wall, chloroplasts in photosynthetic tissues, and a large central vacuole; an animal cell lacks these.
البطاقة ١٢١
السؤال
Which term describes the prokaryotic chromosome-containing region?
الإجابة
the nucleoid
البطاقة ١٢٢
السؤال
Which term describes the internal network of protein filaments?
الإجابة
the cytoskeleton
البطاقة ١٢٣
السؤال
How is genetic material commonly organized in a prokaryotic cell?
الإجابة
The main DNA is usually one circular chromosome in the nucleoid, often accompanied by smaller plasmids.
البطاقة ١٢٤
السؤال
How is microscope magnification calculated?
الإجابة
Magnification = image size ÷ actual size, using the same units.
البطاقة ١٢٥
السؤال
What does microscope resolution describe?
الإجابة
The ability to distinguish two close points as separate.
البطاقة ١٢٦
السؤال
Arrange these from smallest to largest: ribosome, bacterium, animal cell.
الإجابة
Ribosome, bacterium, animal cell.
البطاقة ١٢٧
السؤال
How does the cytoskeleton support intracellular transport?
الإجابة
Motor proteins move vesicles and other cargo along cytoskeletal filaments.
البطاقة ١٢٨
السؤال
Why does a small cell usually exchange materials more efficiently than a geometrically similar large cell?
الإجابة
It has a larger surface-area-to-volume ratio, providing more exchange surface per unit of cell contents.
البطاقة ١٢٩
السؤال
Why is a cell more than a collection of isolated molecules?
الإجابة
Organized interactions among components produce emergent functions such as metabolism, regulation, and reproduction.
البطاقة ١٣٠
السؤال
What major advantage do membrane-bound organelles give eukaryotic cells?
الإجابة
They separate incompatible reactions and create specialized local conditions.
البطاقة ١٣١
السؤال
What is a phospholipid bilayer?
الإجابة
A double layer of phospholipids with hydrophilic heads facing water and hydrophobic tails facing inward.
البطاقة ١٣٢
السؤال
What is the fluid mosaic model?
الإجابة
A model describing membranes as mobile phospholipids containing a changing mosaic of proteins and other components.
البطاقة ١٣٣
السؤال
What is an integral membrane protein?
الإجابة
A protein embedded in the bilayer, often spanning it.
البطاقة ١٣٤
السؤال
What is a peripheral membrane protein?
الإجابة
A protein attached to a membrane surface rather than embedded in the bilayer.
البطاقة ١٣٥
السؤال
Which term describes a double phospholipid layer with inward-facing tails?
الإجابة
a phospholipid bilayer
البطاقة ١٣٦
السؤال
Which term describes the model of a mobile lipid layer containing varied proteins?
الإجابة
the fluid mosaic model
البطاقة ١٣٧
السؤال
Which term describes a protein embedded within the lipid bilayer?
الإجابة
an integral membrane protein
البطاقة ١٣٨
السؤال
Which term describes a protein attached to a membrane surface?
الإجابة
a peripheral membrane protein
البطاقة ١٣٩
السؤال
What is membrane cholesterol?
الإجابة
An amphipathic lipid that buffers membrane fluidity and reduces permeability in animal cells.
البطاقة ١٤٠
السؤال
What is a glycoprotein?
الإجابة
A protein with an attached carbohydrate chain, often used in recognition, adhesion, or signaling.
البطاقة ١٤١
السؤال
What is diffusion?
الإجابة
Net movement of particles from a region of higher concentration to lower concentration due to random motion.
البطاقة ١٤٢
السؤال
What is osmosis?
الإجابة
Net movement of water across a selectively permeable membrane from higher water potential to lower water potential.
البطاقة ١٤٣
السؤال
Which term describes the animal-membrane lipid that buffers fluidity?
الإجابة
membrane cholesterol
البطاقة ١٤٤
السؤال
Which term describes a carbohydrate-bearing protein?
الإجابة
a glycoprotein
البطاقة ١٤٥
السؤال
Which term describes net movement down a concentration gradient?
الإجابة
diffusion
البطاقة ١٤٦
السؤال
Which term describes net water movement across a selectively permeable membrane?
الإجابة
osmosis
البطاقة ١٤٧
السؤال
What is facilitated diffusion?
الإجابة
Passive movement down a gradient through a membrane channel or carrier protein.
البطاقة ١٤٨
السؤال
What is active transport?
الإجابة
Energy-requiring movement of a substance against its concentration or electrochemical gradient.
البطاقة ١٤٩
السؤال
Why is the phospholipid bilayer selectively permeable?
الإجابة
Its hydrophobic interior allows small nonpolar molecules through more readily than ions and most large or polar molecules.
البطاقة ١٥٠
السؤال
How do simple diffusion and facilitated diffusion differ?
الإجابة
Both are passive, but facilitated diffusion uses specific membrane proteins while simple diffusion passes through the bilayer.
البطاقة ١٥١
السؤال
Which term describes passive transport through a channel or carrier?
الإجابة
facilitated diffusion
البطاقة ١٥٢
السؤال
Which term describes energy-dependent transport against a gradient?
الإجابة
active transport
البطاقة ١٥٣
السؤال
How do channel and carrier proteins differ?
الإجابة
Channels provide hydrophilic pores; carriers bind solutes and change shape to move them.
البطاقة ١٥٤
السؤال
How can an ATP-driven pump maintain an ion gradient?
الإجابة
It couples ATP hydrolysis to a conformational change that moves ions against their electrochemical gradient.
البطاقة ١٥٥
السؤال
How does endocytosis move material into a cell?
الإجابة
The plasma membrane folds inward and pinches off a vesicle containing the material.
البطاقة ١٥٦
السؤال
How does exocytosis move material out of a cell?
الإجابة
An intracellular vesicle fuses with the plasma membrane and releases its contents outside.
البطاقة ١٥٧
السؤال
What happens to an animal cell in a strongly hypotonic solution?
الإجابة
Water enters by osmosis; without a cell wall, the cell may swell and lyse.
البطاقة ١٥٨
السؤال
Does molecular movement stop when diffusion reaches equilibrium?
الإجابة
No. Molecules continue moving randomly, but there is no net movement between regions.
البطاقة ١٥٩
السؤال
How does decreasing temperature generally affect membrane fluidity?
الإجابة
It reduces phospholipid movement and makes the membrane less fluid.
البطاقة ١٦٠
السؤال
Why do unsaturated fatty-acid tails increase membrane fluidity?
الإجابة
Their cis double-bond bends prevent phospholipids from packing tightly.
البطاقة ١٦١
السؤال
What changes increase the rate of simple diffusion across a membrane?
الإجابة
A steeper gradient, larger surface area, higher temperature, shorter distance, and greater membrane permeability increase the rate.
البطاقة ١٦٢
السؤال
What is a mitochondrion?
الإجابة
A double-membrane organelle where most aerobic ATP production occurs.
البطاقة ١٦٣
السؤال
What is a chloroplast?
الإجابة
A double-membrane organelle where photosynthesis occurs in plants and algae.
البطاقة ١٦٤
السؤال
What is rough endoplasmic reticulum?
الإجابة
A membrane network bearing ribosomes that synthesizes and begins processing many secreted and membrane proteins.
البطاقة ١٦٥
السؤال
What is smooth endoplasmic reticulum?
الإجابة
A membrane network involved in lipid synthesis, detoxification, and calcium storage.
البطاقة ١٦٦
السؤال
Which term describes the main organelle of aerobic ATP production?
الإجابة
a mitochondrion
البطاقة ١٦٧
السؤال
Which term describes the photosynthetic organelle of plants and algae?
الإجابة
a chloroplast
البطاقة ١٦٨
السؤال
Which term describes the ribosome-studded membrane network?
الإجابة
rough endoplasmic reticulum
البطاقة ١٦٩
السؤال
Which term describes the membrane network that lacks ribosomes and synthesizes lipids?
الإجابة
smooth endoplasmic reticulum
البطاقة ١٧٠
السؤال
What is the Golgi apparatus?
الإجابة
Stacked membranes that modify, sort, and package proteins and lipids into vesicles.
البطاقة ١٧١
السؤال
What is a lysosome?
الإجابة
An acidic enzyme-containing organelle that digests macromolecules and worn cellular components.
البطاقة ١٧٢
السؤال
What is a vesicle?
الإجابة
A small membrane-bound compartment used for transport, storage, or chemical reactions.
البطاقة ١٧٣
السؤال
What is the central vacuole?
الإجابة
A large plant-cell compartment that stores solutes and helps maintain turgor pressure.
البطاقة ١٧٤
السؤال
Which term describes the organelle that modifies and sorts cellular cargo?
الإجابة
the Golgi apparatus
البطاقة ١٧٥
السؤال
Which term describes the acidic digestive organelle?
الإجابة
a lysosome
البطاقة ١٧٦
السؤال
Which term describes a small membrane-bound transport compartment?
الإجابة
a vesicle
البطاقة ١٧٧
السؤال
Which term describes the large plant compartment that supports turgor?
الإجابة
the central vacuole
البطاقة ١٧٨
السؤال
Why can compartmentalization increase metabolic efficiency?
الإجابة
It concentrates enzymes and substrates, maintains suitable local conditions, and separates incompatible reactions.
البطاقة ١٧٩
السؤال
How do mitochondrial cristae support ATP production?
الإجابة
They increase inner-membrane area for electron transport chains and ATP synthase.
البطاقة ١٨٠
السؤال
Why are chloroplast thylakoids arranged as extensive membranes?
الإجابة
They provide a large surface for light-absorbing complexes, electron transport chains, and ATP synthase.
البطاقة ١٨١
السؤال
What is the main function of the nucleolus?
الإجابة
It produces rRNA and assembles ribosomal subunits.
البطاقة ١٨٢
السؤال
Trace a secreted protein from synthesis to release.
الإجابة
Ribosome on rough ER → ER lumen → transport vesicle → Golgi apparatus → secretory vesicle → plasma membrane → exocytosis.
البطاقة ١٨٣
السؤال
Why does a lysosome maintain an acidic interior?
الإجابة
Its hydrolytic enzymes work best at low pH, and acidity helps confine their activity from the cytosol.
البطاقة ١٨٤
السؤال
How do the nucleus, ribosomes, ER, and Golgi cooperate in protein production?
الإجابة
DNA instructions are transcribed in the nucleus; ribosomes translate them; ER folds or modifies many products; Golgi further modifies and sorts them.
البطاقة ١٨٥
السؤال
How are transport vesicles directed to the correct target membrane?
الإجابة
Specific recognition proteins on vesicles and target membranes interact, allowing selective docking and fusion.
البطاقة ١٨٦
السؤال
What is cell differentiation?
الإجابة
The process by which a cell develops specialized structure and function.
البطاقة ١٨٧
السؤال
What is a stem cell?
الإجابة
An unspecialized cell able to self-renew and produce differentiated cells.
البطاقة ١٨٨
السؤال
What is gene expression?
الإجابة
Use of genetic information to produce a functional RNA or protein product.
البطاقة ١٨٩
السؤال
What is a tissue?
الإجابة
A coordinated group of similar or related cells performing a shared function.
البطاقة ١٩٠
السؤال
Which term describes development of specialized cell structure and function?
الإجابة
cell differentiation
البطاقة ١٩١
السؤال
Which term describes an unspecialized self-renewing cell?
الإجابة
a stem cell
البطاقة ١٩٢
السؤال
Which term describes production of a functional product from genetic information?
الإجابة
gene expression
البطاقة ١٩٣
السؤال
Which term describes a group of coordinated cells with a shared function?
الإجابة
a tissue
البطاقة ١٩٤
السؤال
What is an organ?
الإجابة
A structure made of multiple tissues working together for particular functions.
البطاقة ١٩٥
السؤال
What is the organ-system level of biological organization?
الإجابة
A group of organs that coordinate to perform major functions for an organism.
البطاقة ١٩٦
السؤال
What is surface-area-to-volume ratio?
الإجابة
The amount of surface area available relative to the volume it must serve.
البطاقة ١٩٧
السؤال
How can two specialized cells have the same genome but different structures?
الإجابة
They express different sets and amounts of genes, producing different proteins and cellular features.
البطاقة ١٩٨
السؤال
Which term describes a structure composed of multiple tissue types?
الإجابة
an organ
البطاقة ١٩٩
السؤال
Which term describes the level of biological organization formed by coordinated organs?
الإجابة
an organ system
البطاقة ٢٠٠
السؤال
Which term describes surface area available per unit volume?
الإجابة
surface-area-to-volume ratio
البطاقة ٢٠١
السؤال
How is a mammalian red blood cell specialized for oxygen transport?
الإجابة
Its biconcave shape increases exchange area, it is flexible, and loss of its nucleus leaves more space for hemoglobin.
البطاقة ٢٠٢
السؤال
How is a sperm cell specialized for fertilization?
الإجابة
It has a flagellum for movement, many mitochondria for ATP, a haploid nucleus, and an acrosome containing enzymes.
البطاقة ٢٠٣
السؤال
How is a neuron specialized for rapid communication?
الإجابة
Long processes carry signals over distance, branching dendrites receive inputs, and synaptic terminals transmit signals to other cells.
البطاقة ٢٠٤
السؤال
How is a root hair cell specialized for mineral and water uptake?
الإجابة
Its long projection increases surface area, its thin wall shortens the pathway, and membrane transport proteins take up ions.
البطاقة ٢٠٥
السؤال
How is a palisade mesophyll cell specialized for photosynthesis?
الإجابة
It contains many chloroplasts and is positioned near the upper leaf surface where light is strongest.
البطاقة ٢٠٦
السؤال
How do ciliated epithelial cells help protect airways?
الإجابة
Their cilia move mucus containing trapped particles and microbes toward the throat.
البطاقة ٢٠٧
السؤال
Why can extreme specialization reduce a cell's independence?
الإجابة
Resources and structures are committed to a narrow role, so the cell depends on other cells for functions it no longer performs well.
البطاقة ٢٠٨
السؤال
What is water potential?
الإجابة
The potential energy of water per unit volume relative to pure water, used to predict the direction of water movement.
البطاقة ٢٠٩
السؤال
What is solute potential?
الإجابة
The negative contribution of dissolved solutes to water potential.
البطاقة ٢١٠
السؤال
What is pressure potential?
الإجابة
The contribution of physical pressure to water potential.
البطاقة ٢١١
السؤال
What is turgor pressure?
الإجابة
Outward pressure of a plant-cell interior against its cell wall after water uptake.
البطاقة ٢١٢
السؤال
Which term describes the tendency of water to move relative to pure water?
الإجابة
water potential
البطاقة ٢١٣
السؤال
Which term describes the water-potential component lowered by dissolved solutes?
الإجابة
solute potential
البطاقة ٢١٤
السؤال
Which term describes the water-potential component caused by physical pressure?
الإجابة
pressure potential
البطاقة ٢١٥
السؤال
Which term describes pressure of plant-cell contents against the wall?
الإجابة
turgor pressure
البطاقة ٢١٦
السؤال
What is plasmolysis?
الإجابة
Separation of the plasma membrane from the cell wall after a plant cell loses water.
البطاقة ٢١٧
السؤال
What is a flaccid plant cell?
الإجابة
A plant cell with insufficient turgor pressure to be firm.
البطاقة ٢١٨
السؤال
What is an isotonic condition?
الإجابة
A condition in which two solutions have equal effective water potential and no net water movement occurs.
البطاقة ٢١٩
السؤال
In which direction does water move across a permeable membrane?
الإجابة
From higher water potential to lower water potential.
البطاقة ٢٢٠
السؤال
Which term describes membrane separation from the plant cell wall after water loss?
الإجابة
plasmolysis
البطاقة ٢٢١
السؤال
Which term describes a plant cell lacking firm turgor?
الإجابة
a flaccid plant cell
البطاقة ٢٢٢
السؤال
Which term describes equal effective water potential across a membrane?
الإجابة
an isotonic condition
البطاقة ٢٢٣
السؤال
What is the water potential of pure water at standard pressure?
الإجابة
Zero; adding solute makes water potential more negative.
البطاقة ٢٢٤
السؤال
How are water potential, solute potential, and pressure potential related?
الإجابة
Water potential equals solute potential plus pressure potential: Ψ = Ψs + Ψp.
البطاقة ٢٢٥
السؤال
Why does a plant cell usually become turgid rather than burst in a hypotonic solution?
الإجابة
Water entry raises pressure potential, while the rigid cell wall resists further expansion.
البطاقة ٢٢٦
السؤال
What happens to a plant cell placed in a solution with much lower water potential?
الإجابة
Water leaves the cell, turgor falls, and severe loss can cause plasmolysis.
البطاقة ٢٢٧
السؤال
Can two solutions have different solute concentrations but equal water potential?
الإجابة
Yes. A difference in pressure potential can offset a difference in solute potential.
البطاقة ٢٢٨
السؤال
What is an enzyme?
الإجابة
A biological catalyst that increases reaction rate without being consumed.
البطاقة ٢٢٩
السؤال
What is an active site?
الإجابة
The region of an enzyme where substrate binds and catalysis occurs.
البطاقة ٢٣٠
السؤال
What is a substrate?
الإجابة
A reactant molecule on which an enzyme acts.
البطاقة ٢٣١
السؤال
What is activation energy?
الإجابة
The minimum energy input needed for a reaction to begin.
البطاقة ٢٣٢
السؤال
Which term describes a biological catalyst?
الإجابة
an enzyme
البطاقة ٢٣٣
السؤال
Which term describes the substrate-binding catalytic region of an enzyme?
الإجابة
an active site
البطاقة ٢٣٤
السؤال
Which term describes a reactant bound and changed by an enzyme?
الإجابة
a substrate
البطاقة ٢٣٥
السؤال
Which term describes the energy barrier that must be overcome for a reaction?
الإجابة
activation energy
البطاقة ٢٣٦
السؤال
What is the induced-fit model?
الإجابة
The model in which substrate binding changes active-site shape to improve catalytic interactions.
البطاقة ٢٣٧
السؤال
What is enzyme denaturation?
الإجابة
Loss of the active three-dimensional shape of an enzyme, usually causing loss of activity.
البطاقة ٢٣٨
السؤال
What is competitive inhibition?
الإجابة
Inhibition caused by a molecule competing with substrate for the active site.
البطاقة ٢٣٩
السؤال
What is noncompetitive inhibition?
الإجابة
Inhibition caused by binding away from the active site and reducing catalytic function.
البطاقة ٢٤٠
السؤال
Which term describes the model where substrate binding reshapes the active site?
الإجابة
the induced-fit model
البطاقة ٢٤١
السؤال
Which term describes loss of an enzyme's functional shape?
الإجابة
enzyme denaturation
البطاقة ٢٤٢
السؤال
Which term describes inhibition by active-site competition?
الإجابة
competitive inhibition
البطاقة ٢٤٣
السؤال
Which term describes inhibition by binding outside the active site?
الإجابة
noncompetitive inhibition
البطاقة ٢٤٤
السؤال
What is an enzyme optimum?
الإجابة
The condition, such as temperature or pH, at which an enzyme's activity is highest.
البطاقة ٢٤٥
السؤال
What is feedback inhibition?
الإجابة
Control in which a pathway product inhibits an enzyme acting earlier in the pathway.
البطاقة ٢٤٦
السؤال
How does an enzyme increase reaction rate?
الإجابة
It stabilizes the transition state and provides a pathway with lower activation energy.
البطاقة ٢٤٧
السؤال
Why does enzyme activity often rise and then fall as temperature increases?
الإجابة
Molecular collisions initially increase, but excessive heat disrupts enzyme shape and denatures the active site.
البطاقة ٢٤٨
السؤال
Which term describes the condition producing maximum enzyme activity?
الإجابة
an enzyme optimum
البطاقة ٢٤٩
السؤال
Which term describes pathway control by inhibition from an end product?
الإجابة
feedback inhibition
البطاقة ٢٥٠
السؤال
Why does each enzyme have a characteristic pH range?
الإجابة
pH changes the ionization of amino-acid side chains, affecting active-site shape and chemical interactions.
البطاقة ٢٥١
السؤال
Why does increasing substrate concentration eventually stop increasing enzyme rate?
الإجابة
At saturation, nearly all active sites are occupied and enzyme concentration limits the maximum rate.
البطاقة ٢٥٢
السؤال
How does increasing enzyme concentration affect rate when substrate is abundant?
الإجابة
More active sites are available, so the initial rate increases roughly in proportion to enzyme concentration.
البطاقة ٢٥٣
السؤال
What gives an enzyme substrate specificity?
الإجابة
The active site's shape, charge, polarity, and chemical groups complement particular substrates and transition states.
البطاقة ٢٥٤
السؤال
What is one practical advantage of immobilizing an enzyme?
الإجابة
The enzyme can be separated from products and reused while conditions around it are controlled.
البطاقة ٢٥٥
السؤال
Does an enzyme change a reaction's equilibrium position?
الإجابة
No. It speeds forward and reverse reactions but does not change the equilibrium constant or final equilibrium position.
البطاقة ٢٥٦
السؤال
How can high substrate concentration reduce competitive inhibition?
الإجابة
More substrate molecules increase the chance that substrate rather than inhibitor occupies the active site.
البطاقة ٢٥٧
السؤال
Why are metabolic reactions commonly organized into pathways?
الإجابة
A sequence of enzyme-controlled steps allows energy changes and intermediates to be controlled and coupled.
البطاقة ٢٥٨
السؤال
What is ATP?
الإجابة
A nucleotide that transfers usable energy through coupling of its hydrolysis to cellular processes.
البطاقة ٢٥٩
السؤال
What is cellular respiration?
الإجابة
Controlled release of energy from organic molecules to produce ATP.
البطاقة ٢٦٠
السؤال
What is glycolysis?
الإجابة
A cytosolic pathway that splits glucose into two pyruvate molecules and yields a small amount of ATP and reduced electron carriers.
البطاقة ٢٦١
السؤال
What is pyruvate?
الإجابة
The three-carbon product of glycolysis that can enter aerobic or anaerobic pathways.
البطاقة ٢٦٢
السؤال
Which term describes the cell's immediate phosphoryl-group energy carrier?
الإجابة
ATP
البطاقة ٢٦٣
السؤال
Which term describes controlled ATP-producing breakdown of organic molecules?
الإجابة
cellular respiration
البطاقة ٢٦٤
السؤال
Which term describes the cytosolic splitting of glucose into pyruvate?
الإجابة
glycolysis
البطاقة ٢٦٥
السؤال
Which term describes the three-carbon product of glycolysis?
الإجابة
pyruvate
البطاقة ٢٦٦
السؤال
What is aerobic respiration?
الإجابة
Respiration that uses oxygen as the final electron acceptor and produces much more ATP than fermentation.
البطاقة ٢٦٧
السؤال
What is anaerobic metabolism?
الإجابة
ATP-producing metabolism that proceeds without oxygen.
البطاقة ٢٦٨
السؤال
What is fermentation?
الإجابة
An anaerobic pathway that regenerates oxidized electron carriers so glycolysis can continue.
البطاقة ٢٦٩
السؤال
What is oxidation?
الإجابة
Loss of electrons, often accompanied in biology by loss of hydrogen or gain of oxygen.
البطاقة ٢٧٠
السؤال
Which term describes respiration using oxygen as final electron acceptor?
الإجابة
aerobic respiration
البطاقة ٢٧١
السؤال
Which term describes ATP-producing metabolism without oxygen?
الإجابة
anaerobic metabolism
البطاقة ٢٧٢
السؤال
Which term describes anaerobic regeneration of electron carriers after glycolysis?
الإجابة
fermentation
البطاقة ٢٧٣
السؤال
Which term describes loss of electrons?
الإجابة
oxidation
البطاقة ٢٧٤
السؤال
What is reduction?
الإجابة
Gain of electrons, often accompanied in biology by gain of hydrogen or loss of oxygen.
البطاقة ٢٧٥
السؤال
What is a reduced electron carrier?
الإجابة
A molecule such as NADH that carries high-energy electrons and hydrogen from one reaction to another.
البطاقة ٢٧٦
السؤال
What is chemiosmosis?
الإجابة
ATP production driven by ions moving down an electrochemical gradient through ATP synthase.
البطاقة ٢٧٧
السؤال
What is the overall word equation for aerobic respiration of glucose?
الإجابة
Glucose + oxygen → carbon dioxide + water + energy transferred to ATP and heat.
البطاقة ٢٧٨
السؤال
Which term describes gain of electrons?
الإجابة
reduction
البطاقة ٢٧٩
السؤال
Which term describes a molecule carrying high-energy electrons between reactions?
الإجابة
a reduced electron carrier
البطاقة ٢٨٠
السؤال
Which term describes ATP production powered by an ion gradient?
الإجابة
chemiosmosis
البطاقة ٢٨١
السؤال
Where does glycolysis occur?
الإجابة
In the cytosol.
البطاقة ٢٨٢
السؤال
What major stages of aerobic respiration occur in mitochondria?
الإجابة
Pyruvate oxidation and the citric acid cycle occur in the matrix; electron transport and chemiosmosis occur at the inner membrane.
البطاقة ٢٨٣
السؤال
What is oxygen's direct role in aerobic respiration?
الإجابة
It accepts electrons and hydrogen ions at the end of the electron transport chain, forming water.
البطاقة ٢٨٤
السؤال
Why does aerobic respiration yield much more ATP per glucose than fermentation?
الإجابة
It transfers electrons through an electron transport chain and uses oxidative phosphorylation, extracting far more of glucose's energy.
البطاقة ٢٨٥
السؤال
What is the purpose of lactate formation in oxygen-limited animal cells?
الإجابة
It regenerates NAD⁺ so glycolysis can continue producing a small amount of ATP.
البطاقة ٢٨٦
السؤال
What products are formed during alcoholic fermentation in yeast?
الإجابة
Ethanol and carbon dioxide, while NAD⁺ is regenerated.
البطاقة ٢٨٧
السؤال
Why is some energy released by respiration transferred as heat rather than captured in ATP?
الإجابة
Energy conversions are not fully efficient, so part of the chemical energy becomes disordered molecular motion.
البطاقة ٢٨٨
السؤال
What is substrate-level phosphorylation?
الإجابة
Direct transfer of a phosphate group from a metabolic intermediate to ADP to form ATP.
البطاقة ٢٨٩
السؤال
How does electron transport lead to ATP synthesis in mitochondria?
الإجابة
Electron energy pumps protons across the inner membrane; proton flow back through ATP synthase drives ATP formation.
البطاقة ٢٩٠
السؤال
Why can intense exercise increase lactate production?
الإجابة
ATP demand can exceed oxygen delivery and aerobic capacity, so cells regenerate NAD⁺ through lactate formation to sustain glycolysis.
البطاقة ٢٩١
السؤال
What is photosynthesis?
الإجابة
Conversion of light energy into chemical energy used to synthesize organic molecules from carbon dioxide.
البطاقة ٢٩٢
السؤال
What is chlorophyll?
الإجابة
A green pigment that absorbs light energy for photosynthesis.
البطاقة ٢٩٣
السؤال
What is an absorption spectrum?
الإجابة
A graph showing how strongly a pigment absorbs different wavelengths of light.
البطاقة ٢٩٤
السؤال
What is an action spectrum?
الإجابة
A graph showing the rate or effectiveness of photosynthesis at different wavelengths.
البطاقة ٢٩٥
السؤال
Which term describes light-driven synthesis of organic molecules from carbon dioxide?
الإجابة
photosynthesis
البطاقة ٢٩٦
السؤال
Which term describes the principal green photosynthetic pigment?
الإجابة
chlorophyll
البطاقة ٢٩٧
السؤال
Which term describes a graph of pigment absorption versus wavelength?
الإجابة
an absorption spectrum
البطاقة ٢٩٨
السؤال
Which term describes a graph of photosynthetic effectiveness versus wavelength?
الإجابة
an action spectrum
البطاقة ٢٩٩
السؤال
What is photolysis of water?
الإجابة
Light-driven splitting of water that supplies electrons and hydrogen ions and releases oxygen.
البطاقة ٣٠٠
السؤال
What are light-dependent reactions?
الإجابة
Photosynthetic reactions that use light to generate ATP and reduced electron carriers while releasing oxygen.
البطاقة ٣٠١
السؤال
What is the Calvin cycle?
الإجابة
A set of chloroplast reactions that uses ATP and reduced electron carriers to convert carbon dioxide into carbohydrate precursors.
البطاقة ٣٠٢
السؤال
What is carbon fixation?
الإجابة
Incorporation of inorganic carbon dioxide into an organic molecule.
البطاقة ٣٠٣
السؤال
Which term describes light-driven splitting of water?
الإجابة
photolysis of water
البطاقة ٣٠٤
السؤال
Which term describes photosynthetic reactions that directly capture light energy?
الإجابة
light-dependent reactions
البطاقة ٣٠٥
السؤال
Which term describes the carbon-reduction cycle of photosynthesis?
الإجابة
the Calvin cycle
البطاقة ٣٠٦
السؤال
Which term describes incorporation of carbon dioxide into organic matter?
الإجابة
carbon fixation
البطاقة ٣٠٧
السؤال
What is the role of a stoma in photosynthesis?
الإجابة
A pore in the leaf epidermis that regulates carbon-dioxide entry as well as water loss.
البطاقة ٣٠٨
السؤال
What is a limiting factor of photosynthesis?
الإجابة
The environmental factor whose availability currently restricts the photosynthetic rate.
البطاقة ٣٠٩
السؤال
What is the light compensation point?
الإجابة
The light intensity at which photosynthetic carbon uptake equals respiratory carbon release.
البطاقة ٣١٠
السؤال
What is the overall word equation for oxygenic photosynthesis?
الإجابة
Carbon dioxide + water → carbohydrate + oxygen, using light energy.
البطاقة ٣١١
السؤال
Which term describes the regulated leaf pore controlling carbon-dioxide entry for photosynthesis?
الإجابة
a stoma
البطاقة ٣١٢
السؤال
Which term describes the factor currently restricting photosynthetic rate?
الإجابة
a limiting factor
البطاقة ٣١٣
السؤال
Which term describes the light level where photosynthesis and respiration balance?
الإجابة
the light compensation point
البطاقة ٣١٤
السؤال
Where do the main stages of photosynthesis occur in a chloroplast?
الإجابة
Light-dependent reactions occur in thylakoid membranes; carbon-fixation reactions occur in the stroma.
البطاقة ٣١٥
السؤال
What energy conversion occurs during photosynthesis?
الإجابة
Light energy is converted into chemical energy stored first in ATP and reduced carriers and ultimately in organic molecules.
البطاقة ٣١٦
السؤال
From which reactant does the oxygen released by photosynthesis originate?
الإجابة
Water.
البطاقة ٣١٧
السؤال
What role does RuBisCO play in photosynthesis?
الإجابة
It catalyzes fixation of carbon dioxide by adding it to an organic acceptor molecule.
البطاقة ٣١٨
السؤال
What tradeoff is controlled when stomata open?
الإجابة
Opening permits carbon dioxide entry but increases water loss by transpiration.
البطاقة ٣١٩
السؤال
Name three leaf features that support photosynthesis.
الإجابة
A broad surface captures light, a thin structure shortens diffusion paths, and veins supply water and remove sugars; chloroplast-rich cells and stomata also help.
البطاقة ٣٢٠
السؤال
What can a plant do with carbohydrate made by photosynthesis?
الإجابة
Use it in respiration, convert it to storage or structural carbohydrates, or use its carbon to make lipids, amino acids, and other molecules.
البطاقة ٣٢١
السؤال
How are products of the light-dependent reactions used in carbon fixation?
الإجابة
ATP supplies energy and NADPH supplies reducing power for conversion of fixed carbon into carbohydrate precursors.
البطاقة ٣٢٢
السؤال
Why does increasing light intensity eventually stop increasing photosynthetic rate?
الإجابة
Another factor, such as carbon dioxide supply, temperature, or biochemical capacity, becomes limiting.
البطاقة ٣٢٣
السؤال
How can increasing carbon dioxide concentration affect photosynthetic rate?
الإجابة
It can increase the rate until another factor becomes limiting.
البطاقة ٣٢٤
السؤال
Why does photosynthetic rate usually have a temperature optimum?
الإجابة
Enzyme-controlled reactions accelerate with temperature up to an optimum, then decline as enzymes and membranes lose effective function.
البطاقة ٣٢٥
السؤال
Why does an action spectrum broadly resemble the combined absorption spectra of photosynthetic pigments?
الإجابة
Wavelengths absorbed by the pigments supply more energy for photosynthesis than poorly absorbed wavelengths.
البطاقة ٣٢٦
السؤال
What is semiconservative replication?
الإجابة
DNA replication in which each daughter molecule contains one parental strand and one newly synthesized strand.
البطاقة ٣٢٧
السؤال
What is DNA helicase?
الإجابة
An enzyme that unwinds the double helix and separates the strands by disrupting base pairing.
البطاقة ٣٢٨
السؤال
What is DNA polymerase?
الإجابة
An enzyme that adds nucleotides to a growing DNA strand using a template.
البطاقة ٣٢٩
السؤال
What is a primer?
الإجابة
A short nucleic-acid segment providing a free 3′ end from which DNA polymerase can extend.
البطاقة ٣٣٠
السؤال
Which term describes replication producing one old and one new strand per DNA molecule?
الإجابة
semiconservative replication
البطاقة ٣٣١
السؤال
Which term describes the enzyme that separates DNA strands?
الإجابة
DNA helicase
البطاقة ٣٣٢
السؤال
Which term describes the enzyme that builds DNA from a template?
الإجابة
DNA polymerase
البطاقة ٣٣٣
السؤال
Which term describes the short segment providing a starting 3′ end?
الإجابة
a primer
البطاقة ٣٣٤
السؤال
What is the leading strand?
الإجابة
The new DNA strand synthesized continuously toward the replication fork.
البطاقة ٣٣٥
السؤال
What is the lagging strand?
الإجابة
The new DNA strand synthesized discontinuously away from the replication fork.
البطاقة ٣٣٦
السؤال
What is an Okazaki fragment?
الإجابة
A short DNA segment synthesized on the lagging strand.
البطاقة ٣٣٧
السؤال
What is DNA ligase?
الإجابة
An enzyme that seals breaks in the sugar-phosphate backbone, joining DNA fragments.
البطاقة ٣٣٨
السؤال
Which term describes the continuously synthesized daughter strand?
الإجابة
the leading strand
البطاقة ٣٣٩
السؤال
Which term describes the discontinuously synthesized daughter strand?
الإجابة
the lagging strand
البطاقة ٣٤٠
السؤال
Which term describes a short newly made segment of lagging-strand DNA?
الإجابة
an Okazaki fragment
البطاقة ٣٤١
السؤال
Which term describes the enzyme that joins DNA fragments by sealing the backbone?
الإجابة
DNA ligase
البطاقة ٣٤٢
السؤال
How does complementary base pairing ensure accurate DNA copying?
الإجابة
Each template base specifies the nucleotide added opposite it: A pairs with T, and C pairs with G.
البطاقة ٣٤٣
السؤال
Why does DNA polymerase synthesize DNA only 5′ to 3′?
الإجابة
It can add a nucleotide only to the free 3′ hydroxyl group of the growing strand.
البطاقة ٣٤٤
السؤال
When in the cell cycle is nuclear DNA replicated?
الإجابة
During S phase of interphase, before cell division.
البطاقة ٣٤٥
السؤال
How can a replication error become a permanent mutation?
الإجابة
If it escapes proofreading and repair, the altered sequence can be copied in later cell generations.
البطاقة ٣٤٦
السؤال
Why are leading and lagging strands synthesized differently?
الإجابة
The templates are antiparallel while DNA polymerase works only 5′ to 3′, forcing one strand to be made discontinuously.
البطاقة ٣٤٧
السؤال
How do proofreading and repair reduce replication errors?
الإجابة
Incorrectly paired nucleotides are recognized, removed, and replaced before or after replication continues.
البطاقة ٣٤٨
السؤال
What three repeating steps amplify DNA in PCR?
الإجابة
Strand separation by heating, primer annealing during cooling, and DNA extension by a heat-stable polymerase.
البطاقة ٣٤٩
السؤال
What determines which DNA region PCR amplifies?
الإجابة
The sequences and positions of the two primers flanking the target region.
البطاقة ٣٥٠
السؤال
What is transcription?
الإجابة
Synthesis of RNA from a DNA template.
البطاقة ٣٥١
السؤال
What is RNA polymerase?
الإجابة
The enzyme that synthesizes RNA complementary to a DNA template strand.
البطاقة ٣٥٢
السؤال
What is messenger RNA?
الإجابة
RNA carrying a coding sequence from DNA to ribosomes.
البطاقة ٣٥٣
السؤال
What is a codon?
الإجابة
A three-base sequence in mRNA that specifies an amino acid or a translation signal.
البطاقة ٣٥٤
السؤال
Which term describes RNA synthesis from DNA?
الإجابة
transcription
البطاقة ٣٥٥
السؤال
Which term describes the enzyme that builds RNA from a DNA template?
الإجابة
RNA polymerase
البطاقة ٣٥٦
السؤال
Which term describes RNA that carries coding information to ribosomes?
الإجابة
messenger RNA
البطاقة ٣٥٧
السؤال
Which term describes a three-base mRNA unit?
الإجابة
a codon
البطاقة ٣٥٨
السؤال
What is translation?
الإجابة
Synthesis of a polypeptide using the codon sequence of mRNA.
البطاقة ٣٥٩
السؤال
What does a ribosome do during translation?
الإجابة
It reads mRNA and catalyzes polypeptide synthesis using its rRNA-protein machinery.
البطاقة ٣٦٠
السؤال
What is transfer RNA?
الإجابة
RNA that carries a specific amino acid and pairs its anticodon with an mRNA codon.
البطاقة ٣٦١
السؤال
What is an anticodon?
الإجابة
A three-base tRNA sequence complementary to an mRNA codon.
البطاقة ٣٦٢
السؤال
Which term describes polypeptide synthesis from an mRNA sequence?
الإجابة
translation
البطاقة ٣٦٣
السؤال
Which term describes the translation complex that reads mRNA and builds a polypeptide?
الإجابة
a ribosome
البطاقة ٣٦٤
السؤال
Which term describes the adaptor RNA carrying an amino acid?
الإجابة
transfer RNA
البطاقة ٣٦٥
السؤال
Which term describes the tRNA triplet that pairs with a codon?
الإجابة
an anticodon
البطاقة ٣٦٦
السؤال
What is the genetic code?
الإجابة
The set of rules relating mRNA codons to amino acids and translation signals.
البطاقة ٣٦٧
السؤال
What are start and stop codons?
الإجابة
mRNA signals that establish the reading frame or terminate translation.
البطاقة ٣٦٨
السؤال
Where do transcription and translation occur in a eukaryotic cell?
الإجابة
Transcription occurs in the nucleus; translation occurs on ribosomes in the cytoplasm or on rough ER.
البطاقة ٣٦٩
السؤال
How is an mRNA sequence related to its DNA template strand?
الإجابة
It is complementary and antiparallel, with uracil in RNA opposite adenine in DNA.
البطاقة ٣٧٠
السؤال
Which term describes the codon-to-amino-acid rule set?
الإجابة
the genetic code
البطاقة ٣٧١
السؤال
Which term describes codons that begin or end translation?
الإجابة
start and stop codons
البطاقة ٣٧٢
السؤال
What reaction does the ribosome catalyze as a polypeptide grows?
الإجابة
Formation of peptide bonds between adjacent amino acids.
البطاقة ٣٧٣
السؤال
What does it mean that the genetic code is degenerate?
الإجابة
Most amino acids are specified by more than one codon.
البطاقة ٣٧٤
السؤال
How can one mRNA produce many polypeptides quickly?
الإجابة
Multiple ribosomes can translate the same mRNA simultaneously as a polyribosome.
البطاقة ٣٧٥
السؤال
Why is translation not the final step in producing many functional proteins?
الإجابة
The polypeptide must fold and may undergo cleavage, chemical modification, or assembly with other subunits.
البطاقة ٣٧٦
السؤال
How does mRNA compare with the DNA coding strand?
الإجابة
It has the same base sequence except that RNA contains uracil where DNA contains thymine.
البطاقة ٣٧٧
السؤال
What happens during eukaryotic RNA splicing?
الإجابة
Introns are removed and exons are joined to form mature mRNA.
البطاقة ٣٧٨
السؤال
Why must codons be read in the correct reading frame?
الإجابة
Changing the starting position changes every downstream triplet and therefore the amino-acid sequence.
البطاقة ٣٧٩
السؤال
How is the correct amino acid matched to each mRNA codon?
الإجابة
Each tRNA is charged with a particular amino acid, and its anticodon pairs with the complementary codon.
البطاقة ٣٨٠
السؤال
How can a base substitution affect a protein?
الإجابة
It may be silent, change one amino acid, create a stop codon, or sometimes alter RNA processing.
البطاقة ٣٨١
السؤال
What is a mutation?
الإجابة
A change in a DNA sequence or chromosome structure that can be passed to daughter cells.
البطاقة ٣٨٢
السؤال
What is a base substitution?
الإجابة
Replacement of one nucleotide pair by another.
البطاقة ٣٨٣
السؤال
What is an insertion mutation?
الإجابة
Addition of one or more nucleotides to a DNA sequence.
البطاقة ٣٨٤
السؤال
What is a deletion mutation?
الإجابة
Loss of one or more nucleotides from a DNA sequence.
البطاقة ٣٨٥
السؤال
Which term describes a lasting DNA-sequence or chromosome change?
الإجابة
a mutation
البطاقة ٣٨٦
السؤال
Which term describes replacement of one DNA base pair?
الإجابة
a base substitution
البطاقة ٣٨٧
السؤال
Which term describes addition of nucleotides to DNA?
الإجابة
an insertion mutation
البطاقة ٣٨٨
السؤال
Which term describes loss of nucleotides from DNA?
الإجابة
a deletion mutation
البطاقة ٣٨٩
السؤال
What is a frameshift mutation?
الإجابة
A coding-sequence insertion or deletion not divisible by three that changes downstream codon grouping.
البطاقة ٣٩٠
السؤال
What is a silent mutation?
الإجابة
A sequence change that does not alter the encoded amino acid.
البطاقة ٣٩١
السؤال
What is a missense mutation?
الإجابة
A mutation that changes a codon so a different amino acid is incorporated.
البطاقة ٣٩٢
السؤال
What is a nonsense mutation?
الإجابة
A mutation that changes an amino-acid codon into a stop codon.
البطاقة ٣٩٣
السؤال
Which term describes a mutation that shifts downstream codon grouping?
الإجابة
a frameshift mutation
البطاقة ٣٩٤
السؤال
Which term describes a coding change that leaves the amino acid unchanged?
الإجابة
a silent mutation
البطاقة ٣٩٥
السؤال
Which term describes a mutation causing one amino-acid substitution?
الإجابة
a missense mutation
البطاقة ٣٩٦
السؤال
Which term describes a mutation creating a premature stop codon?
الإجابة
a nonsense mutation
البطاقة ٣٩٧
السؤال
How do germline and somatic mutations differ in inheritance?
الإجابة
Germline mutations can enter gametes and be inherited; somatic mutations affect a cell lineage within the individual.
البطاقة ٣٩٨
السؤال
What can cause mutations?
الإجابة
Replication errors, spontaneous chemical changes, radiation, and mutagenic chemicals can alter DNA.
البطاقة ٣٩٩
السؤال
How does DNA repair protect genome stability?
الإجابة
Repair systems detect damaged or mismatched DNA and restore the correct structure or sequence when possible.
البطاقة ٤٠٠
السؤال
Why are mutations essential to evolution despite often being neutral or harmful?
الإجابة
They create new alleles, providing the heritable variation on which selection and drift act.
البطاقة ٤٠١
السؤال
What is the basic role of guide RNA in CRISPR gene editing?
الإجابة
It directs a nuclease to a complementary DNA sequence.
البطاقة ٤٠٢
السؤال
Why can the same type of DNA mutation have effects ranging from none to severe?
الإجابة
Effects depend on location, genetic-code redundancy, protein role, cell type, and environmental context.
البطاقة ٤٠٣
السؤال
How can accumulated mutations contribute to cancer?
الإجابة
Mutations can activate growth-promoting genes or disable genes that restrain division, repair DNA, or trigger cell death.
البطاقة ٤٠٤
السؤال
Why can repairing a CRISPR-induced DNA break produce different editing outcomes?
الإجابة
Different cellular repair pathways may disrupt the target sequence or use a supplied template for a specific change.
البطاقة ٤٠٥
السؤال
What is an off-target effect in gene editing?
الإجابة
An unintended DNA change at a site sufficiently similar to the intended target.
البطاقة ٤٠٦
السؤال
Why does heritable human genome editing raise additional ethical concerns?
الإجابة
Changes could pass to future generations who cannot consent, with uncertain long-term biological and social effects.
البطاقة ٤٠٧
السؤال
What is the cell cycle?
الإجابة
The ordered sequence of cell growth, DNA replication, nuclear division, and cell division.
البطاقة ٤٠٨
السؤال
What is interphase?
الإجابة
The period of growth, normal activity, and DNA replication between nuclear divisions.
البطاقة ٤٠٩
السؤال
What is mitosis?
الإجابة
Nuclear division that usually produces genetically equivalent daughter nuclei.
البطاقة ٤١٠
السؤال
What is cytokinesis?
الإجابة
Division of the cytoplasm to form separate daughter cells.
البطاقة ٤١١
السؤال
Which term describes the ordered sequence from one cell division to the next?
الإجابة
the cell cycle
البطاقة ٤١٢
السؤال
Which term describes the growth and DNA-replication period between divisions?
الإجابة
interphase
البطاقة ٤١٣
السؤال
Which term describes division producing genetically equivalent nuclei?
الإجابة
mitosis
البطاقة ٤١٤
السؤال
Which term describes physical division of the cytoplasm?
الإجابة
cytokinesis
البطاقة ٤١٥
السؤال
What is a chromosome?
الإجابة
One DNA molecule packaged with associated proteins.
البطاقة ٤١٦
السؤال
What are sister chromatids?
الإجابة
The two replicated copies of a chromosome joined before separation.
البطاقة ٤١٧
السؤال
What is a centromere?
الإجابة
The chromosome region that holds sister chromatids together and organizes kinetochore attachment.
البطاقة ٤١٨
السؤال
What is the mitotic spindle?
الإجابة
A microtubule system that attaches to and separates chromosomes during cell division.
البطاقة ٤١٩
السؤال
Which term describes a protein-packaged DNA molecule?
الإجابة
a chromosome
البطاقة ٤٢٠
السؤال
Which term describes joined replicated copies of one chromosome?
الإجابة
sister chromatids
البطاقة ٤٢١
السؤال
Which term describes the chromosome region joining sister chromatids?
الإجابة
a centromere
البطاقة ٤٢٢
السؤال
Which term describes the chromosome-separating microtubule system?
الإجابة
the mitotic spindle
البطاقة ٤٢٣
السؤال
What is the basic sequence of mitosis?
الإجابة
Chromosomes condense, align at the cell equator, sister chromatids separate to opposite poles, and new nuclei form.
البطاقة ٤٢٤
السؤال
Why must DNA replicate before mitosis?
الإجابة
Each chromosome must have two copies so each daughter nucleus can receive a complete genome.
البطاقة ٤٢٥
السؤال
Why are daughter cells from mitosis usually genetically similar?
الإجابة
Replicated sister chromatids are separated so each daughter receives one copy of every chromosome.
البطاقة ٤٢٦
السؤال
What are major roles of mitosis in multicellular organisms?
الإجابة
Growth, tissue repair, cell replacement, and some forms of asexual reproduction.
البطاقة ٤٢٧
السؤال
How do homologous chromosomes differ from sister chromatids?
الإجابة
Homologs carry the same gene loci but may have different alleles; sister chromatids are replicated copies of one chromosome.
البطاقة ٤٢٨
السؤال
What key outcome distinguishes mitosis from meiosis?
الإجابة
Mitosis usually preserves chromosome number and similarity; meiosis halves chromosome number and generates genetically varied haploid cells.
البطاقة ٤٢٩
السؤال
How does cytokinesis commonly occur in animal cells?
الإجابة
A contractile ring tightens the plasma membrane into a cleavage furrow.
البطاقة ٤٣٠
السؤال
How does cytokinesis commonly occur in plant cells?
الإجابة
Vesicles fuse at the center to form a cell plate that develops into new membranes and a cell wall.
البطاقة ٤٣١
السؤال
What is the purpose of cell-cycle checkpoints?
الإجابة
They delay progression when conditions are unsuitable or DNA and chromosome attachment are defective.
البطاقة ٤٣٢
السؤال
How is loss of cell-cycle control related to cancer?
الإجابة
Cells can divide despite damage or growth restraints, producing an expanding abnormal clone.
البطاقة ٤٣٣
السؤال
What is a gene?
الإجابة
A DNA sequence that contributes to a functional product and influences a characteristic or cellular process.
البطاقة ٤٣٤
السؤال
What is an allele?
الإجابة
One of the alternative DNA-sequence forms at a gene locus.
البطاقة ٤٣٥
السؤال
What is a gene locus?
الإجابة
The physical position of a gene on a chromosome.
البطاقة ٤٣٦
السؤال
What is a genotype?
الإجابة
The allele combination of an organism at one or more loci.
البطاقة ٤٣٧
السؤال
Which term describes a functional DNA sequence?
الإجابة
a gene
البطاقة ٤٣٨
السؤال
Which term describes an alternative form of a gene?
الإجابة
an allele
البطاقة ٤٣٩
السؤال
Which term describes a gene's chromosome position?
الإجابة
a gene locus
البطاقة ٤٤٠
السؤال
Which term describes an organism's allele combination?
الإجابة
a genotype
البطاقة ٤٤١
السؤال
What is a phenotype?
الإجابة
An observable or measurable trait produced by genotype and environment.
البطاقة ٤٤٢
السؤال
What is homozygous?
الإجابة
Having two identical alleles at a diploid locus.
البطاقة ٤٤٣
السؤال
What is heterozygous?
الإجابة
Having two different alleles at a diploid locus.
البطاقة ٤٤٤
السؤال
What is a dominant allele?
الإجابة
An allele expressed in the phenotype of a heterozygote under a specified inheritance model.
البطاقة ٤٤٥
السؤال
Which term describes an observable trait resulting from genes and environment?
الإجابة
a phenotype
البطاقة ٤٤٦
السؤال
Which term describes having two identical alleles at a locus?
الإجابة
homozygous
البطاقة ٤٤٧
السؤال
Which term describes having two different alleles at a locus?
الإجابة
heterozygous
البطاقة ٤٤٨
السؤال
Which term describes an allele expressed in a heterozygote?
الإجابة
a dominant allele
البطاقة ٤٤٩
السؤال
What is a recessive allele?
الإجابة
An allele whose phenotype is masked by a dominant allele in a heterozygote.
البطاقة ٤٥٠
السؤال
What is a genetic carrier?
الإجابة
An unaffected heterozygote who can transmit a recessive disease allele.
البطاقة ٤٥١
السؤال
What is a test cross?
الإجابة
A cross with a homozygous recessive individual used to infer an unknown dominant phenotype's genotype.
البطاقة ٤٥٢
السؤال
What is a pedigree?
الإجابة
A diagram showing biological relationships and occurrence of a trait across generations.
البطاقة ٤٥٣
السؤال
Which term describes an allele masked in a heterozygote?
الإجابة
a recessive allele
البطاقة ٤٥٤
السؤال
Which term describes an unaffected heterozygote carrying a recessive disease allele?
الإجابة
a genetic carrier
البطاقة ٤٥٥
السؤال
Which term describes a cross used to reveal an unknown dominant genotype?
الإجابة
a test cross
البطاقة ٤٥٦
السؤال
Which term describes a family diagram tracking a trait across generations?
الإجابة
a pedigree
البطاقة ٤٥٧
السؤال
What does allele segregation mean during gamete formation?
الإجابة
The two alleles at a diploid locus separate so each gamete receives one.
البطاقة ٤٥٨
السؤال
What does a Punnett square predict?
الإجابة
Expected genotype and phenotype probabilities from specified parental gametes, not guaranteed family outcomes.
البطاقة ٤٥٩
السؤال
What phenotypic ratio is expected from Aa × Aa with complete dominance?
الإجابة
Approximately 3 dominant phenotype : 1 recessive phenotype.
البطاقة ٤٦٠
السؤال
What genotypic ratio is expected from Aa × Aa?
الإجابة
1 AA : 2 Aa : 1 aa.
البطاقة ٤٦١
السؤال
What happens in codominance?
الإجابة
Both alleles contribute distinctly to the heterozygous phenotype.
البطاقة ٤٦٢
السؤال
What happens in incomplete dominance?
الإجابة
The heterozygote has a phenotype intermediate between the two homozygotes.
البطاقة ٤٦٣
السؤال
How can environment affect phenotype without changing genotype?
الإجابة
Conditions alter development, physiology, or gene expression, changing the observed trait.
البطاقة ٤٦٤
السؤال
What is the ultimate source of new alleles?
الإجابة
Mutation.
البطاقة ٤٦٥
السؤال
Why are X-linked recessive traits more common in XY individuals?
الإجابة
They have only one X chromosome, so one recessive allele on it can determine the phenotype.
البطاقة ٤٦٦
السؤال
When is the product rule used in genetic probability?
الإجابة
For independent events that must both occur; multiply their probabilities.
البطاقة ٤٦٧
السؤال
When is the sum rule used in genetic probability?
الإجابة
For mutually exclusive alternative outcomes; add their probabilities.
البطاقة ٤٦٨
السؤال
Why do polygenic traits often show continuous variation?
الإجابة
Many loci contribute small effects, creating many possible genotypes and phenotypes, often further influenced by environment.
البطاقة ٤٦٩
السؤال
What pedigree pattern can suggest an autosomal recessive trait?
الإجابة
Unaffected parents can have affected children, and all sexes are affected at similar frequencies.
البطاقة ٤٧٠
السؤال
What is a species?
الإجابة
A group of organisms whose members can potentially interbreed and produce fertile offspring under natural conditions.
البطاقة ٤٧١
السؤال
What is binomial nomenclature?
الإجابة
The two-part scientific naming system using a genus name followed by a specific epithet.
البطاقة ٤٧٢
السؤال
What is taxonomy?
الإجابة
The naming and classification of organisms.
البطاقة ٤٧٣
السؤال
What is a biological domain?
الإجابة
The broadest commonly used taxonomic rank, separating Bacteria, Archaea, and Eukarya.
البطاقة ٤٧٤
السؤال
Which term describes a naturally interbreeding group producing fertile offspring?
الإجابة
a species
البطاقة ٤٧٥
السؤال
Which term describes the genus-plus-specific-epithet naming system?
الإجابة
binomial nomenclature
البطاقة ٤٧٦
السؤال
Which term describes the science of naming and classifying organisms?
الإجابة
taxonomy
البطاقة ٤٧٧
السؤال
Which term describes the broadest common taxonomic rank?
الإجابة
a biological domain
البطاقة ٤٧٨
السؤال
What is biodiversity?
الإجابة
Variation of life at genetic, species, and ecosystem levels.
البطاقة ٤٧٩
السؤال
What is an autotroph?
الإجابة
An organism that makes organic compounds from inorganic carbon using light or chemical energy.
البطاقة ٤٨٠
السؤال
What is a heterotroph?
الإجابة
An organism that obtains organic carbon by consuming other organisms or their products.
٩٦٠ بطاقة
IB Biology SL Flashcards: Complete Course Review
ادرس هذه الرزمة مجانًاسيفتح تطبيق Flashcards لتبدأ الدراسة.
البطاقة ٤٨١
السؤال
What is a unicellular organism?
الإجابة
An organism consisting of one cell that carries out all essential life functions.
البطاقة ٤٨٢
السؤال
Which term describes variation of life across genes, species, and ecosystems?
الإجابة
biodiversity
البطاقة ٤٨٣
السؤال
Which term describes an organism that builds organic matter from inorganic carbon?
الإجابة
an autotroph
البطاقة ٤٨٤
السؤال
Which term describes an organism obtaining organic carbon from other organisms?
الإجابة
a heterotroph
البطاقة ٤٨٥
السؤال
Which term describes an organism made of one cell?
الإجابة
a unicellular organism
البطاقة ٤٨٦
السؤال
What is a multicellular organism?
الإجابة
An organism composed of many cooperating cells, often with specialized cell types.
البطاقة ٤٨٧
السؤال
What is a karyotype?
الإجابة
An ordered display of chromosomes used to examine their number and large-scale structure.
البطاقة ٤٨٨
السؤال
What broad feature distinguishes both Bacteria and Archaea from Eukarya?
الإجابة
Their cells lack a nucleus and other membrane-bound organelles.
البطاقة ٤٨٩
السؤال
What features characterize most plant cells?
الإجابة
Cellulose walls, chloroplasts in photosynthetic tissues, and large vacuoles are typical features.
البطاقة ٤٩٠
السؤال
Which term describes an organism made of many cooperating cells?
الإجابة
a multicellular organism
البطاقة ٤٩١
السؤال
Which term describes an ordered display of an individual's chromosomes?
الإجابة
a karyotype
البطاقة ٤٩٢
السؤال
How do fungi obtain nutrients?
الإجابة
They secrete digestive enzymes and absorb soluble products; their cells usually have chitin-containing walls.
البطاقة ٤٩٣
السؤال
What distinguishes animal nutrition and cell structure?
الإجابة
Animals ingest organic material, and their cells lack cell walls and chloroplasts.
البطاقة ٤٩٤
السؤال
Why are scientific names useful across languages?
الإجابة
A standardized name identifies the same organism internationally and reduces ambiguity from local common names.
البطاقة ٤٩٥
السؤال
Why can genetic diversity improve a population's resilience?
الإجابة
More heritable variation increases the chance that some individuals tolerate new diseases or environmental changes.
البطاقة ٤٩٦
السؤال
What does ecosystem diversity measure?
الإجابة
The variety of habitats, communities, and ecological processes within a region.
البطاقة ٤٩٧
السؤال
Why are Archaea classified separately from Bacteria?
الإجابة
They differ in genetic sequences, membrane chemistry, cell-wall composition, and aspects of molecular machinery.
البطاقة ٤٩٨
السؤال
Why is the biological species concept difficult to apply to fossils or asexual organisms?
الإجابة
Their ability to interbreed and produce fertile offspring cannot be tested in the usual way.
البطاقة ٤٩٩
السؤال
Does a larger chromosome number necessarily mean a more complex organism?
الإجابة
No. Chromosome number varies through fusion, fission, and duplication and does not directly measure biological complexity.
البطاقة ٥٠٠
السؤال
Does genome size reliably predict organismal complexity?
الإجابة
No. Large amounts of noncoding and repeated DNA make genome size a poor simple measure of complexity.
البطاقة ٥٠١
السؤال
What evidence can be combined when classifying organisms?
الإجابة
Molecular sequences, cell structure, anatomy, development, physiology, and reproductive evidence can all contribute.
البطاقة ٥٠٢
السؤال
What is gas exchange?
الإجابة
Diffusion of respiratory gases between an organism and its environment or transport fluid.
البطاقة ٥٠٣
السؤال
What is ventilation?
الإجابة
Bulk movement of air or water over a gas-exchange surface.
البطاقة ٥٠٤
السؤال
What is an alveolus?
الإجابة
A microscopic air sac in the lung where gases diffuse between air and blood.
البطاقة ٥٠٥
السؤال
What is pulmonary surfactant?
الإجابة
A substance lining alveoli that lowers surface tension and reduces collapse.
البطاقة ٥٠٦
السؤال
Which term describes diffusion of oxygen and carbon dioxide across a respiratory surface?
الإجابة
gas exchange
البطاقة ٥٠٧
السؤال
Which term describes bulk movement of respiratory medium over an exchange surface?
الإجابة
ventilation
البطاقة ٥٠٨
السؤال
Which term describes a microscopic lung air sac?
الإجابة
an alveolus
البطاقة ٥٠٩
السؤال
Which term describes the alveolar lining that lowers surface tension?
الإجابة
pulmonary surfactant
البطاقة ٥١٠
السؤال
What is the diaphragm?
الإجابة
A sheet of skeletal muscle whose contraction increases thoracic volume during inhalation.
البطاقة ٥١١
السؤال
What is tidal volume?
الإجابة
The volume of air moved in or out during a normal breath.
البطاقة ٥١٢
السؤال
What is a stoma?
الإجابة
A regulated epidermal pore through which gases diffuse in leaves.
البطاقة ٥١٣
السؤال
What is countercurrent exchange?
الإجابة
Exchange between fluids moving in opposite directions, maintaining a gradient along most of the surface.
البطاقة ٥١٤
السؤال
Which term describes the muscle sheet that expands the thorax during inhalation?
الإجابة
the diaphragm
البطاقة ٥١٥
السؤال
Which term describes air volume moved in one normal breath?
الإجابة
tidal volume
البطاقة ٥١٦
السؤال
Which term describes a regulated leaf gas-exchange pore?
الإجابة
a stoma
البطاقة ٥١٧
السؤال
Which term describes opposite fluid flow that maintains an exchange gradient?
الإجابة
countercurrent exchange
البطاقة ٥١٨
السؤال
What features make an efficient gas-exchange surface?
الإجابة
Large area, short diffusion distance, permeability, and maintained concentration gradients.
البطاقة ٥١٩
السؤال
How is a steep oxygen gradient maintained across alveoli?
الإجابة
Ventilation replenishes alveolar oxygen and blood flow removes absorbed oxygen.
البطاقة ٥٢٠
السؤال
How does diaphragm contraction cause inhalation?
الإجابة
Thoracic volume increases, lung pressure falls below atmospheric pressure, and air flows inward.
البطاقة ٥٢١
السؤال
What drives quiet exhalation?
الإجابة
The diaphragm relaxes and elastic recoil reduces thoracic and lung volume, raising pressure and pushing air out.
البطاقة ٥٢٢
السؤال
Why do ventilation rate and depth increase during exercise?
الإجابة
They increase oxygen uptake and carbon dioxide removal to support higher cellular respiration.
البطاقة ٥٢٣
السؤال
How does leaf structure shorten the pathway for carbon dioxide diffusion?
الإجابة
Stomata open into air spaces, and mesophyll cells expose moist surfaces close to those spaces.
البطاقة ٥٢٤
السؤال
Why does carbon dioxide diffuse from tissues into blood?
الإجابة
Respiring cells produce carbon dioxide, making its partial pressure higher in tissues than in incoming blood.
البطاقة ٥٢٥
السؤال
How does countercurrent flow improve oxygen uptake at fish gills?
الإجابة
Blood continually meets water with a higher oxygen concentration, preserving diffusion along the lamella.
البطاقة ٥٢٦
السؤال
Why does closing stomata reduce both water loss and photosynthesis?
الإجابة
It limits water-vapor diffusion out but also restricts carbon dioxide diffusion into the leaf.
البطاقة ٥٢٧
السؤال
What is a circulatory system?
الإجابة
A transport system that moves a fluid carrying gases, nutrients, wastes, hormones, and heat through an organism.
البطاقة ٥٢٨
السؤال
What is an artery?
الإجابة
A blood vessel carrying blood away from the heart under relatively high pressure.
البطاقة ٥٢٩
السؤال
What is a vein?
الإجابة
A blood vessel carrying blood toward the heart, usually with low pressure and often valves.
البطاقة ٥٣٠
السؤال
What is a capillary?
الإجابة
A microscopic thin-walled vessel where substances exchange between blood and tissues.
البطاقة ٥٣١
السؤال
Which term describes an internal fluid-transport system?
الإجابة
a circulatory system
البطاقة ٥٣٢
السؤال
Which term describes a vessel carrying blood away from the heart?
الإجابة
an artery
البطاقة ٥٣٣
السؤال
Which term describes a vessel carrying blood toward the heart?
الإجابة
a vein
البطاقة ٥٣٤
السؤال
Which term describes a microscopic exchange blood vessel?
الإجابة
a capillary
البطاقة ٥٣٥
السؤال
What is the cardiac cycle?
الإجابة
The repeating sequence of heart-chamber contraction and relaxation that pumps blood.
البطاقة ٥٣٦
السؤال
What is hemoglobin?
الإجابة
An iron-containing protein in red blood cells that binds oxygen reversibly.
البطاقة ٥٣٧
السؤال
What is xylem?
الإجابة
Plant vascular tissue that transports water and mineral ions and provides structural support.
البطاقة ٥٣٨
السؤال
What is phloem?
الإجابة
Plant vascular tissue that transports sucrose and other organic solutes between sources and sinks.
البطاقة ٥٣٩
السؤال
Which term describes the repeating pumping sequence of the heart?
الإجابة
the cardiac cycle
البطاقة ٥٤٠
السؤال
Which term describes the oxygen-carrying protein of red blood cells?
الإجابة
hemoglobin
البطاقة ٥٤١
السؤال
Which term describes plant tissue carrying water and minerals?
الإجابة
xylem
البطاقة ٥٤٢
السؤال
Which term describes plant tissue carrying organic solutes?
الإجابة
phloem
البطاقة ٥٤٣
السؤال
What is transpiration?
الإجابة
Loss of water vapor from plant surfaces, mainly through stomata.
البطاقة ٥٤٤
السؤال
What is phloem translocation?
الإجابة
Movement of organic solutes through phloem from sources to sinks.
البطاقة ٥٤٥
السؤال
How do a source and a sink differ in plant transport?
الإجابة
A source releases assimilates to phloem; a sink removes them for use or storage.
البطاقة ٥٤٦
السؤال
What makes human circulation a double circulation?
الإجابة
Blood passes through the heart once in the pulmonary circuit and again in the systemic circuit during one complete journey.
البطاقة ٥٤٧
السؤال
Which term describes water-vapor loss from plant surfaces?
الإجابة
transpiration
البطاقة ٥٤٨
السؤال
Which term describes movement of organic solutes through phloem?
الإجابة
phloem translocation
البطاقة ٥٤٩
السؤال
Which term describes the exporting and importing regions of phloem transport?
الإجابة
source and sink
البطاقة ٥٥٠
السؤال
How is an artery adapted to high pressure?
الإجابة
It has thick elastic and muscular walls and a relatively narrow lumen.
البطاقة ٥٥١
السؤال
How is a vein adapted to return low-pressure blood?
الإجابة
It has a wide lumen, thinner walls, and valves that reduce backflow.
البطاقة ٥٥٢
السؤال
How does capillary structure support exchange?
الإجابة
One-cell-thick walls give a short diffusion distance; extensive branching gives a large total area; narrow lumens slow flow and keep blood close to tissues.
البطاقة ٥٥٣
السؤال
What determines whether a heart valve opens or closes?
الإجابة
Pressure differences across the valve.
البطاقة ٥٥٤
السؤال
Trace water from soil to the atmosphere through a plant.
الإجابة
Soil → root hairs → root tissues → xylem → leaf mesophyll → leaf air spaces → stomata → atmosphere.
البطاقة ٥٥٥
السؤال
Why may root cells use active transport to absorb mineral ions?
الإجابة
Ion concentrations can be lower in soil than in root cells, so uptake must occur against a gradient.
البطاقة ٥٥٦
السؤال
Why do large multicellular organisms need bulk transport systems?
الإجابة
Their low surface-area-to-volume ratio and long diffusion distances make diffusion alone too slow for whole-body supply.
البطاقة ٥٥٧
السؤال
Why does hemoglobin unload more oxygen in actively respiring tissues?
الإجابة
Lower oxygen and often higher carbon dioxide and acidity reduce hemoglobin's oxygen affinity.
البطاقة ٥٥٨
السؤال
How does transpiration pull water upward through xylem?
الإجابة
Evaporation lowers leaf water potential and creates tension; cohesion transmits the pull through the continuous water column.
البطاقة ٥٥٩
السؤال
How do wind and low humidity generally affect transpiration?
الإجابة
Both maintain a steep water-vapor gradient outside the leaf, increasing transpiration if stomata remain open.
البطاقة ٥٦٠
السؤال
What drives mass flow in phloem?
الإجابة
Sugar loading draws in water and raises pressure at a source; unloading lowers pressure at a sink, producing bulk flow.
البطاقة ٥٦١
السؤال
Can the same plant organ be a source at one time and a sink at another?
الإجابة
Yes. A storage organ may import sugars while filling and export them later during growth or germination.
البطاقة ٥٦٢
السؤال
What is a neuron?
الإجابة
An excitable cell specialized to receive, process, and transmit information.
البطاقة ٥٦٣
السؤال
What is a sensory neuron?
الإجابة
A neuron carrying information from a receptor toward the central nervous system.
البطاقة ٥٦٤
السؤال
What is a motor neuron?
الإجابة
A neuron carrying commands from the central nervous system to an effector.
البطاقة ٥٦٥
السؤال
What is the resting potential?
الإجابة
The voltage difference across an unstimulated neuron's membrane, with the inside negative relative to outside.
البطاقة ٥٦٦
السؤال
Which term describes an excitable information-transmitting cell?
الإجابة
a neuron
البطاقة ٥٦٧
السؤال
Which term describes a neuron carrying receptor information to the CNS?
الإجابة
a sensory neuron
البطاقة ٥٦٨
السؤال
Which term describes a neuron carrying CNS commands to an effector?
الإجابة
a motor neuron
البطاقة ٥٦٩
السؤال
Which term describes the negative-inside voltage of an unstimulated neuron?
الإجابة
the resting potential
البطاقة ٥٧٠
السؤال
What is an action potential?
الإجابة
A brief, self-propagating reversal and restoration of membrane potential along an excitable membrane.
البطاقة ٥٧١
السؤال
What is depolarization?
الإجابة
A change that makes membrane potential less negative, and during an action potential often positive.
البطاقة ٥٧٢
السؤال
What is repolarization?
الإجابة
Return of membrane potential toward its resting negative value after depolarization.
البطاقة ٥٧٣
السؤال
What is a synapse?
الإجابة
A junction where one cell communicates with another cell.
البطاقة ٥٧٤
السؤال
Which term describes a brief propagating change in neuron membrane voltage?
الإجابة
an action potential
البطاقة ٥٧٥
السؤال
Which term describes a membrane-voltage change toward a less negative value?
الإجابة
depolarization
البطاقة ٥٧٦
السؤال
Which term describes return toward resting membrane voltage?
الإجابة
repolarization
البطاقة ٥٧٧
السؤال
Which term describes a communication junction between cells?
الإجابة
a synapse
البطاقة ٥٧٨
السؤال
What is a neurotransmitter?
الإجابة
A chemical released by a neuron that changes the activity of a target cell.
البطاقة ٥٧٩
السؤال
What is the refractory period?
الإجابة
A brief period after an action potential when another is impossible or requires a stronger stimulus.
البطاقة ٥٨٠
السؤال
What is myelin?
الإجابة
An insulating sheath around some axons that speeds impulse conduction.
البطاقة ٥٨١
السؤال
What happens when membrane depolarization reaches threshold?
الإجابة
Voltage-gated channels trigger the self-amplifying events of an action potential.
البطاقة ٥٨٢
السؤال
Which term describes a neuron-released signaling chemical?
الإجابة
a neurotransmitter
البطاقة ٥٨٣
السؤال
Which term describes the recovery interval after an action potential?
الإجابة
the refractory period
البطاقة ٥٨٤
السؤال
Which term describes the insulating axon sheath?
الإجابة
myelin
البطاقة ٥٨٥
السؤال
What does the all-or-none principle mean for an action potential?
الإجابة
Once threshold is reached, the action potential has a characteristic size; stronger stimuli increase frequency, not its amplitude.
البطاقة ٥٨٦
السؤال
How does myelin increase conduction speed?
الإجابة
Depolarizing current travels rapidly beneath myelin and action potentials regenerate mainly at gaps in the sheath.
البطاقة ٥٨٧
السؤال
What is the basic sequence at a chemical synapse?
الإجابة
An impulse triggers neurotransmitter release; it diffuses across the cleft, binds receptors, and alters the postsynaptic cell.
البطاقة ٥٨٨
السؤال
Why can a reflex response be rapid?
الإجابة
A short neural pathway produces an automatic response without waiting for conscious processing.
البطاقة ٥٨٩
السؤال
What is sensory transduction?
الإجابة
Conversion of a physical or chemical stimulus into an electrical signal in a receptor cell.
البطاقة ٥٩٠
السؤال
How does an action potential propagate along an axon?
الإجابة
Local current depolarizes the next membrane region to threshold, opening voltage-gated channels there.
البطاقة ٥٩١
السؤال
Why does an action potential normally travel in one direction along an axon?
الإجابة
The membrane just behind it is refractory and cannot immediately fire again.
البطاقة ٥٩٢
السؤال
How is neurotransmitter action ended?
الإجابة
The transmitter is removed by enzymatic breakdown, reuptake, or diffusion away.
البطاقة ٥٩٣
السؤال
What is sensory adaptation?
الإجابة
Reduced receptor or neural response during a constant, unchanging stimulus.
البطاقة ٥٩٤
السؤال
How can a drug alter synaptic transmission?
الإجابة
It may mimic or block a transmitter, change its release, or change its removal from the synaptic cleft.
البطاقة ٥٩٥
السؤال
What is an organ system?
الإجابة
A group of organs coordinating to perform major functions for an organism.
البطاقة ٥٩٦
السؤال
What is a hormone?
الإجابة
A signaling molecule released into transport fluid and acting on target cells with suitable receptors.
البطاقة ٥٩٧
السؤال
What is an endocrine gland?
الإجابة
A gland that secretes hormones into extracellular fluid and blood rather than through a duct.
البطاقة ٥٩٨
السؤال
What is a hormone target cell?
الإجابة
A cell able to respond because it has the appropriate receptor.
البطاقة ٥٩٩
السؤال
Which term describes a coordinated group of organs?
الإجابة
an organ system
البطاقة ٦٠٠
السؤال
Which term describes a long-distance chemical messenger carried in body fluid?
الإجابة
a hormone
البطاقة ٦٠١
السؤال
Which term describes a ductless hormone-secreting gland?
الإجابة
an endocrine gland
البطاقة ٦٠٢
السؤال
Which term describes a cell with a receptor for a particular hormone?
الإجابة
a hormone target cell
البطاقة ٦٠٣
السؤال
What is digestion?
الإجابة
Mechanical and chemical breakdown of food into molecules small enough to absorb.
البطاقة ٦٠٤
السؤال
What is absorption?
الإجابة
Movement of digested nutrients across an exchange surface into blood or lymph.
البطاقة ٦٠٥
السؤال
What is peristalsis?
الإجابة
Coordinated waves of smooth-muscle contraction that move material through the digestive tract.
البطاقة ٦٠٦
السؤال
What is an intestinal villus?
الإجابة
A finger-like projection increasing the absorptive surface of the small intestine.
البطاقة ٦٠٧
السؤال
Which term describes breakdown of food into absorbable molecules?
الإجابة
digestion
البطاقة ٦٠٨
السؤال
Which term describes movement of digested nutrients into transport fluids?
الإجابة
absorption
البطاقة ٦٠٩
السؤال
Which term describes wave-like gut contractions moving contents?
الإجابة
peristalsis
البطاقة ٦١٠
السؤال
Which term describes a finger-like intestinal absorption projection?
الإجابة
an intestinal villus
البطاقة ٦١١
السؤال
What is excretion?
الإجابة
Removal of metabolic waste products from the body.
البطاقة ٦١٢
السؤال
What is a nephron?
الإجابة
The microscopic functional unit of the kidney that filters blood and modifies filtrate into urine.
البطاقة ٦١٣
السؤال
What is ultrafiltration?
الإجابة
Pressure-driven filtration of small molecules from blood into a kidney capsule while cells and most proteins remain in blood.
البطاقة ٦١٤
السؤال
What is selective reabsorption?
الإجابة
Recovery of useful substances and regulated amounts of water and ions from kidney filtrate into blood.
البطاقة ٦١٥
السؤال
Which term describes removal of metabolic wastes?
الإجابة
excretion
البطاقة ٦١٦
السؤال
Which term describes the kidney's microscopic functional unit?
الإجابة
a nephron
البطاقة ٦١٧
السؤال
Which term describes pressure filtration at the start of a nephron?
الإجابة
ultrafiltration
البطاقة ٦١٨
السؤال
Which term describes return of useful substances from kidney filtrate to blood?
الإجابة
selective reabsorption
البطاقة ٦١٩
السؤال
What is skeletal muscle?
الإجابة
Striated voluntary muscle attached to the skeleton and used for movement and posture.
البطاقة ٦٢٠
السؤال
What is an antagonistic muscle pair?
الإجابة
Two muscles producing opposite movements at a joint because muscles pull but do not push.
البطاقة ٦٢١
السؤال
How do nervous and endocrine signaling generally differ?
الإجابة
Neural signals are rapid and targeted; hormonal signals are usually slower, longer-lasting, and distributed through body fluids.
البطاقة ٦٢٢
السؤال
Why does a circulating hormone affect only some cells?
الإجابة
Only target cells express receptors that recognize the hormone and activate a response.
البطاقة ٦٢٣
السؤال
Which term describes voluntary striated muscle that moves the skeleton?
الإجابة
skeletal muscle
البطاقة ٦٢٤
السؤال
Which term describes two muscles producing opposite joint movements?
الإجابة
an antagonistic muscle pair
البطاقة ٦٢٥
السؤال
What is the final absorbable product of most dietary carbohydrate digestion?
الإجابة
Monosaccharides, especially glucose.
البطاقة ٦٢٦
السؤال
What are the main absorbable products of protein digestion?
الإجابة
Amino acids and small peptides that are completed to amino acids during absorption.
البطاقة ٦٢٧
السؤال
How is the small intestine adapted for absorption?
الإجابة
Folds, villi, and microvilli increase area; a thin epithelium, rich blood supply, and lymph vessels support transport.
البطاقة ٦٢٨
السؤال
Name three integrative roles of the liver.
الإجابة
It processes absorbed nutrients, regulates blood chemistry, detoxifies substances, produces bile, and converts ammonia to urea; any three are sufficient.
البطاقة ٦٢٩
السؤال
Why are blood cells and most plasma proteins absent from normal kidney filtrate?
الإجابة
They are too large to cross the filtration barrier.
البطاقة ٦٣٠
السؤال
How do muscles move a bone at a joint?
الإجابة
Contraction shortens the muscle, pulling through a tendon on the bone.
البطاقة ٦٣١
السؤال
Why are antagonistic muscles needed at many joints?
الإجابة
A muscle can pull in one direction but cannot push itself back, so an opposing muscle produces the reverse movement.
البطاقة ٦٣٢
السؤال
Why must organ systems be integrated rather than acting independently?
الإجابة
Each system depends on materials, signals, waste removal, and stable conditions supplied by other systems.
البطاقة ٦٣٣
السؤال
Why do many absorbed lipids enter lymph before blood?
الإجابة
Intestinal cells package them into lipoprotein particles too large to enter ordinary blood capillaries directly.
البطاقة ٦٣٤
السؤال
Why is glucose normally absent from final urine?
الإجابة
Filtered glucose is selectively reabsorbed into blood when transporter capacity is not exceeded.
البطاقة ٦٣٥
السؤال
How do respiratory, circulatory, and muscular systems cooperate during exercise?
الإجابة
Ventilation supplies oxygen, circulation transports gases and fuels, and muscles use ATP while returning carbon dioxide, heat, and metabolites.
البطاقة ٦٣٦
السؤال
How do liver, circulation, and kidneys cooperate in nitrogen-waste removal?
الإجابة
The liver converts toxic ammonia to urea, blood carries urea, and kidneys filter and excrete it.
البطاقة ٦٣٧
السؤال
What is a pathogen?
الإجابة
A biological agent capable of causing disease.
البطاقة ٦٣٨
السؤال
What is an antigen?
الإجابة
A molecule recognized specifically by an antibody or lymphocyte receptor.
البطاقة ٦٣٩
السؤال
What is innate immunity?
الإجابة
Rapid, nonspecific defense mechanisms present without prior exposure.
البطاقة ٦٤٠
السؤال
What is adaptive immunity?
الإجابة
Specific defense that develops through lymphocyte activation and can form memory.
البطاقة ٦٤١
السؤال
Which term describes a disease-causing biological agent?
الإجابة
a pathogen
البطاقة ٦٤٢
السؤال
Which term describes a molecule specifically recognized by adaptive immune receptors?
الإجابة
an antigen
البطاقة ٦٤٣
السؤال
Which term describes rapid nonspecific immune defense?
الإجابة
innate immunity
البطاقة ٦٤٤
السؤال
Which term describes specific immune defense capable of memory?
الإجابة
adaptive immunity
البطاقة ٦٤٥
السؤال
What is a phagocyte?
الإجابة
A cell that engulfs and digests microbes, particles, or damaged cells.
البطاقة ٦٤٦
السؤال
What is a lymphocyte?
الإجابة
An adaptive immune cell with receptors specific to particular antigens.
البطاقة ٦٤٧
السؤال
What is an antibody?
الإجابة
A secreted immunoglobulin that binds a specific antigen.
البطاقة ٦٤٨
السؤال
What is a B lymphocyte?
الإجابة
A lymphocyte that can differentiate into antibody-secreting plasma cells and memory cells.
البطاقة ٦٤٩
السؤال
Which term describes an engulfing immune cell?
الإجابة
a phagocyte
البطاقة ٦٥٠
السؤال
Which term describes an antigen-specific adaptive immune cell?
الإجابة
a lymphocyte
البطاقة ٦٥١
السؤال
Which term describes a secreted antigen-binding immunoglobulin?
الإجابة
an antibody
البطاقة ٦٥٢
السؤال
Which term describes the lymphocyte lineage that produces antibody-secreting cells?
الإجابة
a B lymphocyte
البطاقة ٦٥٣
السؤال
What is a helper T cell?
الإجابة
A lymphocyte that coordinates immune responses through contact signals and cytokines.
البطاقة ٦٥٤
السؤال
What is an immune memory cell?
الإجابة
A long-lived lymphocyte that responds rapidly after re-exposure to its antigen.
البطاقة ٦٥٥
السؤال
What is vaccination?
الإجابة
Deliberate exposure to a safe form or component of an antigen to generate protective immune memory.
البطاقة ٦٥٦
السؤال
What is an antibiotic?
الإجابة
A substance that kills bacteria or inhibits their growth at clinically useful doses.
البطاقة ٦٥٧
السؤال
Which term describes the T cell that coordinates other immune cells?
الإجابة
a helper T cell
البطاقة ٦٥٨
السؤال
Which term describes a long-lived lymphocyte enabling faster re-exposure response?
الإجابة
an immune memory cell
البطاقة ٦٥٩
السؤال
Which term describes safe antigen exposure used to create immune memory?
الإجابة
vaccination
البطاقة ٦٦٠
السؤال
Which term describes a drug acting against bacteria?
الإجابة
an antibiotic
البطاقة ٦٦١
السؤال
What are examples of first-line defenses against pathogens?
الإجابة
Intact skin, mucus, cilia, antimicrobial secretions, stomach acidity, and competing microbiota.
البطاقة ٦٦٢
السؤال
How does inflammation help defend damaged tissue?
الإجابة
It increases local blood flow and vessel permeability and recruits immune cells and defensive molecules.
البطاقة ٦٦٣
السؤال
What happens during phagocytosis?
الإجابة
A cell surrounds a particle in a vesicle, then fuses it with digestive compartments to destroy or process it.
البطاقة ٦٦٤
السؤال
How can antibodies help eliminate a pathogen?
الإجابة
They can neutralize targets, block attachment, clump particles, and mark them for phagocytosis or complement attack.
البطاقة ٦٦٥
السؤال
Why can a vaccine generate protection without causing the full disease?
الإجابة
It presents antigen in a weakened, inactivated, partial, or encoded form that stimulates immunity with much lower risk.
البطاقة ٦٦٦
السؤال
Why do antibiotics not treat viral infections?
الإجابة
Viruses lack the bacterial structures and independent metabolic processes targeted by antibiotics.
البطاقة ٦٦٧
السؤال
What determines the antigen specificity of a lymphocyte?
الإجابة
The molecular shape and chemistry of its unique surface receptor.
البطاقة ٦٦٨
السؤال
What is clonal selection?
الإجابة
An antigen activates lymphocytes with matching receptors, causing them to proliferate and differentiate.
البطاقة ٦٦٩
السؤال
Why is a secondary adaptive immune response usually faster and stronger?
الإجابة
Memory cells are more numerous and activate rapidly, producing effective cells and antibodies sooner.
البطاقة ٦٧٠
السؤال
How can high vaccination coverage protect some unvaccinated people?
الإجابة
Reduced transmission makes encounters with infectious individuals less likely, though protection is incomplete and pathogen-dependent.
البطاقة ٦٧١
السؤال
How does antibiotic use select for resistant bacteria?
الإجابة
Susceptible bacteria are removed while resistant variants survive and reproduce, increasing resistance-allele frequency.
البطاقة ٦٧٢
السؤال
Why can unnecessary or incomplete antibiotic exposure promote resistance?
الإجابة
It creates selection favoring resistant cells while potentially leaving surviving bacteria to multiply and spread.
البطاقة ٦٧٣
السؤال
What is an allergy?
الإجابة
An immune response to a normally harmless antigen that causes tissue symptoms or damage.
البطاقة ٦٧٤
السؤال
What is asexual reproduction?
الإجابة
Production of offspring from one parent without fusion of gametes.
البطاقة ٦٧٥
السؤال
What is sexual reproduction?
الإجابة
Production of offspring involving fusion of haploid gametes.
البطاقة ٦٧٦
السؤال
What is a gamete?
الإجابة
A haploid reproductive cell able to fuse with another gamete.
البطاقة ٦٧٧
السؤال
What is fertilization?
الإجابة
Fusion of gamete nuclei to form a diploid zygote.
البطاقة ٦٧٨
السؤال
Which term describes reproduction without gamete fusion?
الإجابة
asexual reproduction
البطاقة ٦٧٩
السؤال
Which term describes reproduction involving gamete fusion?
الإجابة
sexual reproduction
البطاقة ٦٨٠
السؤال
Which term describes a haploid reproductive cell?
الإجابة
a gamete
البطاقة ٦٨١
السؤال
Which term describes fusion of gamete nuclei?
الإجابة
fertilization
البطاقة ٦٨٢
السؤال
What is a zygote?
الإجابة
The diploid cell formed by fertilization.
البطاقة ٦٨٣
السؤال
What is meiosis?
الإجابة
Cell division that halves chromosome number and usually produces genetically varied haploid cells.
البطاقة ٦٨٤
السؤال
What is ovulation?
الإجابة
Release of a secondary oocyte from an ovary.
البطاقة ٦٨٥
السؤال
What is implantation?
الإجابة
Attachment and embedding of an early embryo in the uterine lining.
البطاقة ٦٨٦
السؤال
Which term describes the first diploid cell after fertilization?
الإجابة
a zygote
البطاقة ٦٨٧
السؤال
Which term describes division producing varied haploid cells?
الإجابة
meiosis
البطاقة ٦٨٨
السؤال
Which term describes release of an oocyte from an ovary?
الإجابة
ovulation
البطاقة ٦٨٩
السؤال
Which term describes embedding of an early embryo in the uterine lining?
الإجابة
implantation
البطاقة ٦٩٠
السؤال
What is the placenta?
الإجابة
A temporary organ that exchanges materials between maternal and fetal blood supplies without normally mixing them directly.
البطاقة ٦٩١
السؤال
What is pollination?
الإجابة
Transfer of pollen from an anther to a receptive stigma.
البطاقة ٦٩٢
السؤال
Why does sexual reproduction usually produce more genetic variation than asexual reproduction?
الإجابة
Meiosis reshuffles alleles and random fertilization combines genomes from two gametes.
البطاقة ٦٩٣
السؤال
Why must gametes be haploid?
الإجابة
Fusion of two haploid gametes restores the diploid chromosome number instead of doubling it each generation.
البطاقة ٦٩٤
السؤال
Which term describes the maternal-fetal exchange organ?
الإجابة
the placenta
البطاقة ٦٩٥
السؤال
Which term describes transfer of pollen to a stigma?
الإجابة
pollination
البطاقة ٦٩٦
السؤال
What are major roles of FSH in the ovarian cycle?
الإجابة
It stimulates follicle development and supports estrogen secretion.
البطاقة ٦٩٧
السؤال
What is a major role of the mid-cycle LH surge?
الإجابة
It triggers ovulation and formation of the corpus luteum.
البطاقة ٦٩٨
السؤال
How does estrogen contribute to the uterine cycle?
الإجابة
It promotes repair and thickening of the uterine lining after menstruation.
البطاقة ٦٩٩
السؤال
How does progesterone contribute to the uterine cycle?
الإجابة
It maintains a thick, secretory uterine lining after ovulation.
البطاقة ٧٠٠
السؤال
Where does human fertilization usually occur?
الإجابة
In an oviduct, before the early embryo reaches the uterus.
البطاقة ٧٠١
السؤال
What happens after compatible pollen reaches a flower's stigma?
الإجابة
A pollen tube grows toward an ovule and delivers male nuclei for fertilization.
البطاقة ٧٠٢
السؤال
Why does menstruation usually begin if pregnancy does not occur?
الإجابة
The corpus luteum degenerates, progesterone and estrogen fall, and the uterine lining is no longer maintained.
البطاقة ٧٠٣
السؤال
What substances commonly cross the placenta between mother and fetus?
الإجابة
Oxygen and nutrients move toward the fetus; carbon dioxide and nitrogenous wastes move toward the mother.
البطاقة ٧٠٤
السؤال
How can contraception prevent pregnancy in different ways?
الإجابة
Methods can inhibit ovulation, block sperm from reaching an egg, prevent fertilization, or permanently interrupt the reproductive ducts.
البطاقة ٧٠٥
السؤال
What is homeostasis?
الإجابة
Maintenance of internal conditions within ranges compatible with normal function despite change.
البطاقة ٧٠٦
السؤال
What is negative feedback?
الإجابة
Control in which a deviation triggers responses that oppose the original change.
البطاقة ٧٠٧
السؤال
What is a set point?
الإجابة
The target value or range around which a regulated variable is maintained.
البطاقة ٧٠٨
السؤال
What is a homeostatic receptor?
الإجابة
A sensor that detects a change in a regulated variable.
البطاقة ٧٠٩
السؤال
Which term describes maintenance of a stable functional internal environment?
الإجابة
homeostasis
البطاقة ٧١٠
السؤال
Which term describes feedback that counteracts a deviation?
الإجابة
negative feedback
البطاقة ٧١١
السؤال
Which term describes the target around which a variable is regulated?
الإجابة
a set point
البطاقة ٧١٢
السؤال
Which term describes the sensor in a feedback system?
الإجابة
a homeostatic receptor
البطاقة ٧١٣
السؤال
What is a control center?
الإجابة
The component that compares information with a target and coordinates a response.
البطاقة ٧١٤
السؤال
What is an effector?
الإجابة
A muscle, gland, or other component that carries out a control response.
البطاقة ٧١٥
السؤال
What is thermoregulation?
الإجابة
Control of body temperature within a functional range.
البطاقة ٧١٦
السؤال
What is vasodilation?
الإجابة
Widening of blood vessels, often increasing blood flow near the skin.
البطاقة ٧١٧
السؤال
Which term describes the feedback component that evaluates input and directs a response?
الإجابة
a control center
البطاقة ٧١٨
السؤال
Which term describes the component that executes a physiological response?
الإجابة
an effector
البطاقة ٧١٩
السؤال
Which term describes physiological regulation of body temperature?
الإجابة
thermoregulation
البطاقة ٧٢٠
السؤال
Which term describes widening of blood vessels?
الإجابة
vasodilation
البطاقة ٧٢١
السؤال
What is vasoconstriction?
الإجابة
Narrowing of blood vessels, often reducing blood flow near the skin.
البطاقة ٧٢٢
السؤال
What is insulin?
الإجابة
A pancreatic hormone that lowers elevated blood glucose by promoting uptake and storage.
البطاقة ٧٢٣
السؤال
What is glucagon?
الإجابة
A pancreatic hormone that raises low blood glucose by promoting release of stored fuel.
البطاقة ٧٢٤
السؤال
What are the main components of a homeostatic feedback loop?
الإجابة
A regulated variable, receptor, control center, effectors, and responses that alter the variable.
البطاقة ٧٢٥
السؤال
Which term describes narrowing of blood vessels?
الإجابة
vasoconstriction
البطاقة ٧٢٦
السؤال
Which term describes the pancreatic hormone that lowers blood glucose?
الإجابة
insulin
البطاقة ٧٢٧
السؤال
Which term describes the pancreatic hormone that raises blood glucose?
الإجابة
glucagon
البطاقة ٧٢٨
السؤال
What happens when blood glucose rises after a meal?
الإجابة
Insulin secretion increases, promoting glucose uptake and storage so blood glucose falls toward its normal range.
البطاقة ٧٢٩
السؤال
What happens when blood glucose falls during fasting?
الإجابة
Glucagon secretion increases, promoting glycogen breakdown and glucose release by the liver.
البطاقة ٧٣٠
السؤال
How does sweating cool the body?
الإجابة
Evaporation of water from skin transfers heat to the environment.
البطاقة ٧٣١
السؤال
How does skin vasodilation increase heat loss?
الإجابة
It brings more warm blood near the surface, increasing transfer of heat to the environment.
البطاقة ٧٣٢
السؤال
How does shivering warm the body?
الإجابة
Rapid involuntary muscle contractions increase respiration and heat production.
البطاقة ٧٣٣
السؤال
Does homeostasis keep internal conditions perfectly constant?
الإجابة
No. Variables fluctuate within controlled ranges around target values.
البطاقة ٧٣٤
السؤال
How does ADH help conserve water?
الإجابة
It increases water permeability in kidney collecting ducts, so more water is reabsorbed and urine becomes more concentrated.
البطاقة ٧٣٥
السؤال
How should ADH secretion change during dehydration?
الإجابة
It should increase, promoting greater water reabsorption by the kidneys.
البطاقة ٧٣٦
السؤال
How does positive feedback differ from negative feedback?
الإجابة
Positive feedback amplifies a change until an endpoint; negative feedback opposes a change and stabilizes a variable.
البطاقة ٧٣٧
السؤال
Why can diabetes mellitus cause persistently high blood glucose?
الإجابة
Insulin production may be insufficient or target cells may respond poorly to insulin.
البطاقة ٧٣٨
السؤال
What is biological evolution?
الإجابة
Change in heritable characteristics or allele frequencies of a population across generations.
البطاقة ٧٣٩
السؤال
What is allele frequency?
الإجابة
The proportion of gene copies in a population represented by a particular allele.
البطاقة ٧٤٠
السؤال
What is microevolution?
الإجابة
Evolutionary change in allele frequencies within populations over relatively short timescales.
البطاقة ٧٤١
السؤال
What is speciation?
الإجابة
Evolutionary formation of new species.
البطاقة ٧٤٢
السؤال
Which term describes change in a population's heritable composition across generations?
الإجابة
biological evolution
البطاقة ٧٤٣
السؤال
Which term describes the proportion of a population's gene copies that are one allele?
الإجابة
allele frequency
البطاقة ٧٤٤
السؤال
Which term describes short-timescale allele-frequency change within populations?
الإجابة
microevolution
البطاقة ٧٤٥
السؤال
Which term describes formation of new species?
الإجابة
speciation
البطاقة ٧٤٦
السؤال
What is reproductive isolation?
الإجابة
Barriers that prevent or greatly reduce gene flow between populations.
البطاقة ٧٤٧
السؤال
What is allopatric speciation?
الإجابة
Speciation after populations become geographically separated and diverge.
البطاقة ٧٤٨
السؤال
What is sympatric speciation?
الإجابة
Speciation without geographic separation, through reproductive isolation within the same area.
البطاقة ٧٤٩
السؤال
What are homologous structures?
الإجابة
Structures similar because they were inherited from a common ancestor, even if their functions differ.
البطاقة ٧٥٠
السؤال
Which term describes barriers reducing gene flow between populations?
الإجابة
reproductive isolation
البطاقة ٧٥١
السؤال
Which term describes speciation following geographic separation?
الإجابة
allopatric speciation
البطاقة ٧٥٢
السؤال
Which term describes speciation within the same geographic area?
الإجابة
sympatric speciation
البطاقة ٧٥٣
السؤال
Which term describes structures similar through common ancestry?
الإجابة
homologous structures
البطاقة ٧٥٤
السؤال
What are analogous structures?
الإجابة
Structures with similar functions that evolved independently rather than from the same ancestral structure.
البطاقة ٧٥٥
السؤال
What is a common ancestor?
الإجابة
An ancestral population from which two or more descendant lineages evolved.
البطاقة ٧٥٦
السؤال
How does the fossil record provide evidence for evolution?
الإجابة
It documents organisms from different times, including appearance, change, persistence, and extinction of lineages.
البطاقة ٧٥٧
السؤال
How do DNA and protein sequences provide evidence of common ancestry?
الإجابة
Shared sequences are inherited; greater similarity generally indicates more recent common ancestry.
البطاقة ٧٥٨
السؤال
Which term describes functionally similar structures of independent evolutionary origin?
الإجابة
analogous structures
البطاقة ٧٥٩
السؤال
Which term describes an ancestral population shared by descendant lineages?
الإجابة
a common ancestor
البطاقة ٧٦٠
السؤال
What is the evolutionary significance of extinction?
الإجابة
It permanently ends a lineage and can alter ecological opportunities and the future diversification of survivors.
البطاقة ٧٦١
السؤال
Do individual organisms evolve during their lifetimes?
الإجابة
No. Individuals develop and acclimate; evolution is heritable change in populations across generations.
البطاقة ٧٦٢
السؤال
Why is evolution represented as a branching tree rather than a ladder?
الإجابة
Lineages split from common ancestors; living species are not arranged as stages toward a single goal.
البطاقة ٧٦٣
السؤال
How can island species support evolutionary explanations?
الإجابة
Their similarities to nearby mainland ancestors and unique local adaptations fit divergence after colonization and isolation.
البطاقة ٧٦٤
السؤال
How can geographic isolation lead to reproductive isolation?
الإجابة
Separated populations accumulate different mutations and experience different selection and drift until interbreeding is reduced.
البطاقة ٧٦٥
السؤال
Why can continuing gene flow slow speciation?
الإجابة
Movement of alleles between populations counteracts genetic divergence.
البطاقة ٧٦٦
السؤال
Why can unrelated species evolve similar traits?
الإجابة
Similar environmental challenges can favor similar functional solutions through convergent evolution.
البطاقة ٧٦٧
السؤال
Which parts of evolution are random and which are nonrandom?
الإجابة
Mutation and many sampling effects are random with respect to need; natural selection nonrandomly favors variants that reproduce better in a given environment.
البطاقة ٧٦٨
السؤال
What is conservation biology?
الإجابة
The science and practice of protecting biodiversity, ecological processes, and evolutionary potential.
البطاقة ٧٦٩
السؤال
What is habitat fragmentation?
الإجابة
Division of continuous habitat into smaller, isolated patches.
البطاقة ٧٧٠
السؤال
What is an endangered species?
الإجابة
A species facing a high risk of extinction in the wild.
البطاقة ٧٧١
السؤال
What is in situ conservation?
الإجابة
Protection of species in their natural habitats and ecological communities.
البطاقة ٧٧٢
السؤال
Which term describes the protection of biodiversity and ecological processes?
الإجابة
conservation biology
البطاقة ٧٧٣
السؤال
Which term describes division of habitat into isolated patches?
الإجابة
habitat fragmentation
البطاقة ٧٧٤
السؤال
Which term describes a species at high risk of extinction?
الإجابة
an endangered species
البطاقة ٧٧٥
السؤال
Which term describes conservation within natural habitat?
الإجابة
in situ conservation
البطاقة ٧٧٦
السؤال
What is ex situ conservation?
الإجابة
Protection of organisms or genetic material outside the natural habitat.
البطاقة ٧٧٧
السؤال
What is a population bottleneck?
الإجابة
A sharp population reduction that can remove genetic variation by chance.
البطاقة ٧٧٨
السؤال
What is a wildlife corridor?
الإجابة
Habitat connecting isolated patches to permit movement and gene flow.
البطاقة ٧٧٩
السؤال
What major human-driven processes threaten biodiversity?
الإجابة
Habitat loss, overexploitation, invasive species, pollution, and climate change.
البطاقة ٧٨٠
السؤال
Which term describes conservation outside natural habitat?
الإجابة
ex situ conservation
البطاقة ٧٨١
السؤال
Which term describes a severe population reduction that loses genetic diversity?
الإجابة
a population bottleneck
البطاقة ٧٨٢
السؤال
Which term describes habitat linking isolated populations?
الإجابة
a wildlife corridor
البطاقة ٧٨٣
السؤال
What makes a protected area more effective than a boundary alone?
الإجابة
Adequate size, representative habitat, enforcement, connectivity, local support, and management of external threats.
البطاقة ٧٨٤
السؤال
Why is long-term population monitoring important in conservation?
الإجابة
It reveals trends, tests whether management works, and provides early warning of decline.
البطاقة ٧٨٥
السؤال
How can ecosystem services support the case for conservation?
الإجابة
Healthy ecosystems provide benefits such as pollination, water purification, carbon storage, soil formation, and cultural value.
البطاقة ٧٨٦
السؤال
Why are very small populations especially vulnerable to extinction?
الإجابة
Chance events, inbreeding, low genetic diversity, and difficulty finding mates can reinforce decline.
البطاقة ٧٨٧
السؤال
What are benefits and limits of captive-breeding programs?
الإجابة
They can prevent immediate extinction and manage breeding, but may lose diversity, alter behavior, and fail without safe habitat for release.
البطاقة ٧٨٨
السؤال
Why can controlling an invasive species aid conservation?
الإجابة
It can reduce predation, competition, disease, or habitat alteration affecting native species.
البطاقة ٧٨٩
السؤال
Why must conservation priorities consider more than species count?
الإجابة
Endemism, evolutionary distinctness, ecological roles, threat severity, feasibility, and human needs also matter.
البطاقة ٧٩٠
السؤال
What is an adaptation?
الإجابة
A heritable characteristic that increases reproductive success in a particular environment.
البطاقة ٧٩١
السؤال
What is acclimation?
الإجابة
A reversible physiological or behavioral adjustment by an individual to environmental change.
البطاقة ٧٩٢
السؤال
What is a structural adaptation?
الإجابة
An inherited anatomical feature that improves performance in an environment.
البطاقة ٧٩٣
السؤال
What is a physiological adaptation?
الإجابة
An inherited functional or biochemical feature that improves performance in an environment.
البطاقة ٧٩٤
السؤال
Which term describes a heritable trait improving reproductive success in context?
الإجابة
an adaptation
البطاقة ٧٩٥
السؤال
Which term describes an individual's reversible adjustment to environmental change?
الإجابة
acclimation
البطاقة ٧٩٦
السؤال
Which term describes an adaptive anatomical feature?
الإجابة
a structural adaptation
البطاقة ٧٩٧
السؤال
Which term describes an adaptive functional or biochemical feature?
الإجابة
a physiological adaptation
البطاقة ٧٩٨
السؤال
What is a behavioral adaptation?
الإجابة
An inherited behavior pattern that improves survival or reproduction.
البطاقة ٧٩٩
السؤال
What is an environmental tolerance range?
الإجابة
The range of an abiotic condition within which an organism can survive and reproduce.
البطاقة ٨٠٠
السؤال
What is evolutionary fitness?
الإجابة
Relative contribution of an individual or genotype to future generations.
البطاقة ٨٠١
السؤال
How can a thick cuticle and reduced leaves help a desert plant?
الإجابة
The cuticle lowers surface permeability, while smaller leaves reduce the area from which water can evaporate.
البطاقة ٨٠٢
السؤال
Which term describes an adaptive behavior pattern?
الإجابة
a behavioral adaptation
البطاقة ٨٠٣
السؤال
Which term describes the survivable range of an abiotic condition?
الإجابة
an environmental tolerance range
البطاقة ٨٠٤
السؤال
Which term describes relative reproductive contribution to future generations?
الإجابة
evolutionary fitness
البطاقة ٨٠٥
السؤال
How can a streamlined body adapt an aquatic animal to movement?
الإجابة
It reduces drag, lowering the energy needed to move through water.
البطاقة ٨٠٦
السؤال
Does an organism develop an adaptation because it needs one?
الإجابة
No. Heritable variants arise without regard to need, and selection changes their frequencies across generations.
البطاقة ٨٠٧
السؤال
Why may organisms from different thermal environments have enzymes with different temperature optima?
الإجابة
Selection favors protein structures that balance flexibility and stability under local temperatures.
البطاقة ٨٠٨
السؤال
Why is an adaptation rarely beneficial in every environment?
الإجابة
Traits carry costs and their advantage depends on local resources, competitors, predators, and physical conditions.
البطاقة ٨٠٩
السؤال
How does phenotypic plasticity differ from genetic adaptation?
الإجابة
Plasticity lets one genotype produce different phenotypes; adaptation is a heritable population trait shaped across generations.
البطاقة ٨١٠
السؤال
What is local adaptation?
الإجابة
A population has higher fitness in its home environment than foreign populations because selection favored local traits.
البطاقة ٨١١
السؤال
What is an ecological niche?
الإجابة
The set of environmental conditions, resources, interactions, and functional roles associated with a species.
البطاقة ٨١٢
السؤال
What is a habitat?
الإجابة
The physical place or environment where an organism lives.
البطاقة ٨١٣
السؤال
What is a fundamental niche?
الإجابة
The full range of conditions and resources a species could use without limiting biotic interactions.
البطاقة ٨١٤
السؤال
What is a realized niche?
الإجابة
The conditions and resources a species actually uses after competition and other interactions.
البطاقة ٨١٥
السؤال
Which term describes a species' environmental requirements and ecological role?
الإجابة
an ecological niche
البطاقة ٨١٦
السؤال
Which term describes the place where an organism lives?
الإجابة
a habitat
البطاقة ٨١٧
السؤال
Which term describes the potential niche without limiting biotic interactions?
الإجابة
a fundamental niche
البطاقة ٨١٨
السؤال
Which term describes the niche actually occupied in nature?
الإجابة
a realized niche
البطاقة ٨١٩
السؤال
What is competition?
الإجابة
An interaction in which organisms reduce one another's access to a limited resource.
البطاقة ٨٢٠
السؤال
What is mutualism?
الإجابة
An interaction in which both participating species benefit.
البطاقة ٨٢١
السؤال
What is predation?
الإجابة
An interaction in which one organism kills and consumes another.
البطاقة ٨٢٢
السؤال
How does a habitat differ from a niche?
الإجابة
A habitat is where an organism lives; a niche includes how it uses conditions and resources and interacts there.
البطاقة ٨٢٣
السؤال
Which term describes an interaction over a limited resource that harms both competitors?
الإجابة
competition
البطاقة ٨٢٤
السؤال
Which term describes an interspecific interaction benefiting both partners?
الإجابة
mutualism
البطاقة ٨٢٥
السؤال
Which term describes an interaction where one organism kills and eats another?
الإجابة
predation
البطاقة ٨٢٦
السؤال
What kinds of factors define a niche?
الإجابة
Abiotic factors such as temperature and moisture, plus biotic factors such as food, competitors, predators, and partners.
البطاقة ٨٢٧
السؤال
What does competitive exclusion predict?
الإجابة
Species with effectively identical niches cannot coexist indefinitely under stable conditions; one is excluded or niches diverge.
البطاقة ٨٢٨
السؤال
How can resource partitioning reduce competition?
الإجابة
Species use different resources, places, or times, reducing niche overlap.
البطاقة ٨٢٩
السؤال
What is a keystone species?
الإجابة
A species whose effect on community structure is disproportionately large relative to its abundance.
البطاقة ٨٣٠
السؤال
Why can an introduced species expand rapidly in a new community?
الإجابة
It may encounter abundant resources, suitable climate, and fewer predators, pathogens, or competitors.
البطاقة ٨٣١
السؤال
Can an organism alter the niche conditions of other species?
الإجابة
Yes. Ecosystem engineers modify habitat structure or resource availability, changing opportunities for other organisms.
البطاقة ٨٣٢
السؤال
What is a population?
الإجابة
Individuals of the same species living in the same area at the same time.
البطاقة ٨٣٣
السؤال
What is an ecological community?
الإجابة
Populations of different species living and interacting in an area.
البطاقة ٨٣٤
السؤال
What is an ecosystem?
الإجابة
A community together with its physical environment and their interactions.
البطاقة ٨٣٥
السؤال
What is carrying capacity?
الإجابة
The population size an environment can sustain over time under given conditions.
البطاقة ٨٣٦
السؤال
Which term describes same-species individuals sharing an area and time?
الإجابة
a population
البطاقة ٨٣٧
السؤال
Which term describes interacting populations of different species?
الإجابة
an ecological community
البطاقة ٨٣٨
السؤال
Which term describes a community plus its abiotic environment?
الإجابة
an ecosystem
البطاقة ٨٣٩
السؤال
Which term describes the long-term supportable population size?
الإجابة
carrying capacity
البطاقة ٨٤٠
السؤال
What is population density?
الإجابة
The number of individuals per unit area or volume.
البطاقة ٨٤١
السؤال
What is a limiting factor?
الإجابة
A resource or condition that restricts population growth or distribution.
البطاقة ٨٤٢
السؤال
What is a density-dependent factor?
الإجابة
A factor whose effect strengthens as population density increases.
البطاقة ٨٤٣
السؤال
What is a density-independent factor?
الإجابة
A factor whose effect is not primarily determined by population density.
البطاقة ٨٤٤
السؤال
Which term describes individuals per unit area or volume?
الإجابة
population density
البطاقة ٨٤٥
السؤال
Which term describes a resource or condition restricting a population?
الإجابة
a limiting factor
البطاقة ٨٤٦
السؤال
Which term describes a factor with stronger effects at higher density?
الإجابة
a density-dependent factor
البطاقة ٨٤٧
السؤال
Which term describes a factor acting largely regardless of population density?
الإجابة
a density-independent factor
البطاقة ٨٤٨
السؤال
What is exponential population growth?
الإجابة
Growth at a constant per-capita rate, producing a J-shaped curve under ideal conditions.
البطاقة ٨٤٩
السؤال
What is logistic population growth?
الإجابة
Growth that slows as population size approaches carrying capacity, producing an S-shaped model.
البطاقة ٨٥٠
السؤال
What four processes directly change population size?
الإجابة
Births and immigration increase it; deaths and emigration decrease it.
البطاقة ٨٥١
السؤال
Under what conditions can exponential growth occur temporarily?
الإجابة
Resources are abundant and limiting effects such as competition, disease, and predation are weak.
البطاقة ٨٥٢
السؤال
Which term describes J-shaped growth at constant per-capita rate?
الإجابة
exponential population growth
البطاقة ٨٥٣
السؤال
Which term describes S-shaped growth that slows near carrying capacity?
الإجابة
logistic population growth
البطاقة ٨٥٤
السؤال
Why is infectious disease often density dependent?
الإجابة
Close or frequent contact at high density increases transmission opportunities.
البطاقة ٨٥٥
السؤال
Give an example of a density-independent population factor.
الإجابة
A severe storm, wildfire, drought, or freeze can affect populations regardless of their initial density.
البطاقة ٨٥٦
السؤال
When is quadrat sampling useful?
الإجابة
For estimating abundance or frequency of sessile or slow-moving organisms in defined areas.
البطاقة ٨٥٧
السؤال
What can a transect reveal?
الإجابة
How species occurrence or abundance changes along an environmental gradient.
البطاقة ٨٥٨
السؤال
What can happen when a population overshoots carrying capacity?
الإجابة
Resource depletion may raise mortality or lower reproduction, causing decline or oscillation.
البطاقة ٨٥٩
السؤال
What is the basic mark–recapture estimate of population size?
الإجابة
First sample marked × second sample total ÷ marked individuals recaptured.
البطاقة ٨٦٠
السؤال
What assumptions improve a mark–recapture estimate?
الإجابة
Marks persist and do not affect survival, marked individuals mix, capture probability is similar, and the population is effectively closed.
البطاقة ٨٦١
السؤال
Why does a correlation between two population variables not prove causation?
الإجابة
A third factor, reverse influence, chance, or biased sampling could produce the association.
البطاقة ٨٦٢
السؤال
What is a trophic level?
الإجابة
A feeding position in a food chain or web.
البطاقة ٨٦٣
السؤال
What is a producer?
الإجابة
An autotroph that converts inorganic carbon into organic matter.
البطاقة ٨٦٤
السؤال
What is a consumer?
الإجابة
An organism obtaining energy and matter by eating other organisms or organic material.
البطاقة ٨٦٥
السؤال
What is a decomposer?
الإجابة
An organism that externally digests dead material and wastes and absorbs the products.
البطاقة ٨٦٦
السؤال
Which term describes a feeding position in an ecosystem?
الإجابة
a trophic level
البطاقة ٨٦٧
السؤال
Which term describes an autotroph forming organic matter?
الإجابة
a producer
البطاقة ٨٦٨
السؤال
Which term describes an organism feeding on other organic matter?
الإجابة
a consumer
البطاقة ٨٦٩
السؤال
Which term describes an organism digesting dead organic matter externally?
الإجابة
a decomposer
البطاقة ٨٧٠
السؤال
What is a food chain?
الإجابة
A linear representation of feeding and energy-transfer relationships.
البطاقة ٨٧١
السؤال
What is a food web?
الإجابة
A network of interconnected feeding relationships in a community.
البطاقة ٨٧٢
السؤال
What is gross primary productivity?
الإجابة
The total rate at which producers capture energy into organic matter.
البطاقة ٨٧٣
السؤال
What is net primary productivity?
الإجابة
Producer energy stored as new biomass after subtracting producer respiration from gross primary productivity.
البطاقة ٨٧٤
السؤال
Which term describes a linear feeding sequence?
الإجابة
a food chain
البطاقة ٨٧٥
السؤال
Which term describes a network of connected food chains?
الإجابة
a food web
البطاقة ٨٧٦
السؤال
Which term describes the total producer energy-capture rate?
الإجابة
gross primary productivity
البطاقة ٨٧٧
السؤال
Which term describes producer biomass gain after respiration?
الإجابة
net primary productivity
البطاقة ٨٧٨
السؤال
What is ecological productivity?
الإجابة
The rate of biomass or energy production per unit area or volume.
البطاقة ٨٧٩
السؤال
What is a biogeochemical cycle?
الإجابة
Movement of an element or compound through organisms and the physical environment.
البطاقة ٨٨٠
السؤال
Why is less energy available at each higher trophic level?
الإجابة
Not all biomass is eaten or digested, and organisms use energy in respiration, movement, maintenance, and heat loss.
البطاقة ٨٨١
السؤال
Why does energy flow rather than cycle through an ecosystem?
الإجابة
Energy enters mainly as light and ultimately disperses as heat, which ecosystems cannot fully recycle.
البطاقة ٨٨٢
السؤال
Which term describes the rate of biomass or energy production?
الإجابة
ecological productivity
البطاقة ٨٨٣
السؤال
Which term describes cycling of matter through living and nonliving reservoirs?
الإجابة
a biogeochemical cycle
البطاقة ٨٨٤
السؤال
Why can matter cycle through an ecosystem?
الإجابة
Atoms are conserved and repeatedly transferred among organisms, detritus, soil, water, and atmosphere.
البطاقة ٨٨٥
السؤال
Why is a pyramid of energy always upright?
الإجابة
Usable energy decreases between trophic levels because every transfer includes losses.
البطاقة ٨٨٦
السؤال
How are gross and net primary productivity related?
الإجابة
NPP = GPP − producer respiration.
البطاقة ٨٨٧
السؤال
How do decomposers support nutrient cycling?
الإجابة
They break down dead material and wastes, releasing inorganic nutrients for reuse.
البطاقة ٨٨٨
السؤال
What processes move carbon rapidly between organisms and the atmosphere?
الإجابة
Photosynthesis removes carbon dioxide; respiration, decomposition, and combustion release it.
البطاقة ٨٨٩
السؤال
Why is nitrogen fixation important?
الإجابة
It converts atmospheric nitrogen gas into forms that can enter biological nitrogen metabolism.
البطاقة ٨٩٠
السؤال
How can excess nitrogen or phosphorus cause eutrophication?
الإجابة
Nutrient enrichment drives algal growth; decomposition of the biomass consumes oxygen and can create hypoxic water.
البطاقة ٨٩١
السؤال
Why can a persistent pollutant reach higher concentrations at higher trophic levels?
الإجابة
Predators consume contaminant stored in many prey, and the substance is not readily broken down or excreted.
البطاقة ٨٩٢
السؤال
How is trophic-transfer efficiency calculated?
الإجابة
Energy or biomass gained by the higher trophic level ÷ energy or biomass available at the lower level × 100%.
البطاقة ٨٩٣
السؤال
What is phenotypic variation?
الإجابة
Differences in observable traits among individuals of a population.
البطاقة ٨٩٤
السؤال
What is heritable variation?
الإجابة
Trait differences that can be transmitted genetically to offspring.
البطاقة ٨٩٥
السؤال
What is a selection pressure?
الإجابة
An environmental factor causing differences in survival or reproduction among phenotypes.
البطاقة ٨٩٦
السؤال
What is relative fitness?
الإجابة
An individual's reproductive success compared with others in the population.
البطاقة ٨٩٧
السؤال
Which term describes observable differences among individuals?
الإجابة
phenotypic variation
البطاقة ٨٩٨
السؤال
Which term describes genetically transmissible trait differences?
الإجابة
heritable variation
البطاقة ٨٩٩
السؤال
Which term describes an environmental factor producing differential reproductive success?
الإجابة
a selection pressure
البطاقة ٩٠٠
السؤال
Which term describes reproductive success relative to other individuals?
الإجابة
relative fitness
البطاقة ٩٠١
السؤال
What is directional selection?
الإجابة
Selection favoring one extreme phenotype and shifting a population's trait distribution.
البطاقة ٩٠٢
السؤال
What is stabilizing selection?
الإجابة
Selection favoring intermediate phenotypes and acting against extremes.
البطاقة ٩٠٣
السؤال
What is disruptive selection?
الإجابة
Selection favoring both extreme phenotypes over intermediates.
البطاقة ٩٠٤
السؤال
What is sexual selection?
الإجابة
Selection arising from differences in mating success.
البطاقة ٩٠٥
السؤال
Which term describes selection shifting a trait toward one extreme?
الإجابة
directional selection
البطاقة ٩٠٦
السؤال
Which term describes selection favoring intermediate phenotypes?
الإجابة
stabilizing selection
البطاقة ٩٠٧
السؤال
Which term describes selection favoring both trait extremes?
الإجابة
disruptive selection
البطاقة ٩٠٨
السؤال
Which term describes selection caused by unequal mating success?
الإجابة
sexual selection
البطاقة ٩٠٩
السؤال
What conditions are required for natural selection?
الإجابة
Individuals vary, some variation is heritable, more offspring are produced than can reproduce, and variants differ in reproductive success.
البطاقة ٩١٠
السؤال
How does natural selection produce antibiotic-resistant bacterial populations?
الإجابة
Existing resistant variants survive treatment and reproduce more than susceptible bacteria.
البطاقة ٩١١
السؤال
Does an antibiotic cause bacteria to mutate specifically toward resistance?
الإجابة
No. Resistance variants arise without regard to need; treatment selects among them.
البطاقة ٩١٢
السؤال
Can an individual become genetically adapted through natural selection?
الإجابة
No. Selection acts on individuals, but adaptation is a population change across generations.
البطاقة ٩١٣
السؤال
How does artificial selection differ from natural selection?
الإجابة
Humans choose breeding traits in artificial selection; environmental conditions determine differential reproduction in natural selection.
البطاقة ٩١٤
السؤال
How does natural selection change a population?
الإجابة
Individuals with advantageous heritable variants leave more offspring, increasing those alleles over generations.
البطاقة ٩١٥
السؤال
Why is fitness environment-dependent?
الإجابة
A trait that improves reproduction in one environment may be neutral or costly in another.
البطاقة ٩١٦
السؤال
How does genetic drift differ from natural selection?
الإجابة
Drift changes allele frequencies by chance sampling; selection changes them through consistent fitness differences.
البطاقة ٩١٧
السؤال
What is ecosystem stability?
الإجابة
The capacity of an ecosystem to maintain or recover its structure and functions despite disturbance.
البطاقة ٩١٨
السؤال
What is an ecological tipping point?
الإجابة
A threshold beyond which feedbacks can drive a large and difficult-to-reverse ecosystem shift.
البطاقة ٩١٩
السؤال
What is a mesocosm?
الإجابة
A controlled, simplified ecosystem used to investigate ecological processes under more realistic conditions than a small laboratory vessel.
البطاقة ٩٢٠
السؤال
What is a sustainable yield?
الإجابة
A harvest rate that can continue without causing long-term resource decline under prevailing conditions.
البطاقة ٩٢١
السؤال
Which term describes the capacity of an ecosystem to persist or recover after disturbance?
الإجابة
ecosystem stability
البطاقة ٩٢٢
السؤال
Which term describes a threshold triggering a major hard-to-reverse ecosystem shift?
الإجابة
an ecological tipping point
البطاقة ٩٢٣
السؤال
Which term describes a controlled model ecosystem used for experiments?
الإجابة
a mesocosm
البطاقة ٩٢٤
السؤال
Which term describes a harvest rate that avoids long-term depletion?
الإجابة
a sustainable yield
البطاقة ٩٢٥
السؤال
What is eutrophication?
الإجابة
Nutrient enrichment of water that stimulates excess primary production and can lead to oxygen depletion.
البطاقة ٩٢٦
السؤال
What is biomagnification?
الإجابة
Increase in concentration of a persistent pollutant at successively higher trophic levels.
البطاقة ٩٢٧
السؤال
What is rewilding?
الإجابة
Ecosystem restoration that rebuilds natural processes, species interactions, and self-sustaining ecological function.
البطاقة ٩٢٨
السؤال
What features can make an ecosystem more stable?
الإجابة
Diverse functional roles, connected habitats, intact food webs, nutrient cycling, and balancing feedbacks can help the system resist or recover from disturbance.
البطاقة ٩٢٩
السؤال
Which term describes nutrient enrichment that can deplete oxygen in water?
الإجابة
eutrophication
البطاقة ٩٣٠
السؤال
Which term describes increasing pollutant concentration up a food chain?
الإجابة
biomagnification
البطاقة ٩٣١
السؤال
Which term describes restoration focused on natural processes and self-sustaining ecosystems?
الإجابة
rewilding
البطاقة ٩٣٢
السؤال
How could extensive Amazon deforestation push the ecosystem toward a tipping point?
الإجابة
Loss of trees can reduce rainfall recycling and increase heat and fire, which cause further forest loss and may shift large areas toward a drier state.
البطاقة ٩٣٣
السؤال
What are a benefit and a limitation of using a mesocosm?
الإجابة
It allows controlled experiments with interacting organisms, but its simplified scale cannot reproduce every process or long-term influence in a natural ecosystem.
البطاقة ٩٣٤
السؤال
Why should a fishery harvest below an uncertain maximum sustainable yield?
الإجابة
Population estimates and recruitment vary, so a safety margin reduces the chance that error or a poor breeding year drives long-term decline.
البطاقة ٩٣٥
السؤال
How can intensive agriculture reduce ecosystem stability?
الإجابة
Habitat loss, low crop diversity, soil degradation, heavy water use, pesticides, and nutrient runoff can weaken food webs and ecosystem processes.
البطاقة ٩٣٦
السؤال
Why can microplastic pollution harm aquatic ecosystems?
الإجابة
Small persistent particles can be ingested, carry additives or other pollutants, damage feeding and tissues, and move through food webs.
البطاقة ٩٣٧
السؤال
How can rewilding improve ecosystem stability?
الإجابة
Restoring native species, habitat connections, and natural disturbance or grazing processes can rebuild feedbacks and allow the ecosystem to maintain itself with less intervention.
البطاقة ٩٣٨
السؤال
What is the greenhouse effect?
الإجابة
Warming caused when atmospheric gases absorb and re-emit outgoing infrared radiation.
البطاقة ٩٣٩
السؤال
What is a greenhouse gas?
الإجابة
An atmospheric gas that absorbs infrared radiation at wavelengths emitted by Earth.
البطاقة ٩٤٠
السؤال
What is carbon dioxide (CO₂)?
الإجابة
A long-lived greenhouse gas increased mainly by fossil-fuel combustion, cement production, and land-use change.
البطاقة ٩٤١
السؤال
What is methane (CH₄)?
الإجابة
A potent greenhouse gas emitted by sources including fossil-fuel systems, livestock, rice cultivation, wetlands, and waste.
البطاقة ٩٤٢
السؤال
Which term describes warming from absorption and re-emission of infrared radiation?
الإجابة
the greenhouse effect
البطاقة ٩٤٣
السؤال
Which term describes an atmospheric infrared-absorbing gas?
الإجابة
a greenhouse gas
البطاقة ٩٤٤
السؤال
Which term describes the long-lived greenhouse gas strongly increased by fossil fuels?
الإجابة
carbon dioxide (CO₂)
البطاقة ٩٤٥
السؤال
Which term describes the potent short-lived greenhouse gas from biological and fossil sources?
الإجابة
methane (CH₄)
البطاقة ٩٤٦
السؤال
What is albedo?
الإجابة
The fraction of incoming radiation reflected by a surface.
البطاقة ٩٤٧
السؤال
What is a carbon sink?
الإجابة
A reservoir that absorbs more carbon than it releases over a specified period.
البطاقة ٩٤٨
السؤال
What is ocean acidification?
الإجابة
Decline in seawater pH caused mainly by absorption of human-emitted carbon dioxide.
البطاقة ٩٤٩
السؤال
What is climate change?
الإجابة
A persistent change in the statistical patterns of climate over decades or longer.
البطاقة ٩٥٠
السؤال
Which term describes surface reflectivity?
الإجابة
albedo
البطاقة ٩٥١
السؤال
Which term describes a reservoir with net carbon uptake?
الإجابة
a carbon sink
البطاقة ٩٥٢
السؤال
Which term describes seawater pH decline from absorbed carbon dioxide?
الإجابة
ocean acidification
البطاقة ٩٥٣
السؤال
Which term describes long-term change in climate patterns?
الإجابة
climate change
البطاقة ٩٥٤
السؤال
What is the enhanced greenhouse effect?
الإجابة
Additional warming caused by human-driven increases in greenhouse-gas concentrations.
البطاقة ٩٥٥
السؤال
How do climate mitigation and climate adaptation differ?
الإجابة
Mitigation limits the magnitude of climate change; adaptation reduces harm from changes that occur.
البطاقة ٩٥٦
السؤال
How does increasing greenhouse-gas concentration alter Earth's energy balance?
الإجابة
Less outgoing infrared energy initially escapes to space, so the climate warms until energy balance is restored at a higher temperature.
البطاقة ٩٥٧
السؤال
How can melting ice amplify warming?
الإجابة
Less bright ice lowers albedo, so darker land or water absorbs more solar energy and causes further warming.
البطاقة ٩٥٨
السؤال
How can climate change alter species distributions?
الإجابة
Temperature, rainfall, seasons, sea level, and interactions shift, moving or shrinking areas with suitable conditions.
البطاقة ٩٥٩
السؤال
Why can ocean acidification harm calcifying organisms?
الإجابة
Carbonate chemistry changes, reducing availability of carbonate ions used to build calcium-carbonate structures.
البطاقة ٩٦٠
السؤال
How can ecosystem protection contribute to climate mitigation?
الإجابة
Protecting forests, wetlands, soils, and coastal habitats can avoid emissions and maintain or increase carbon storage.
٩٦٠ بطاقة
IB Biology SL Flashcards: Complete Course Review
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