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.
Über dieses Lernkartenset
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.
Karten in diesem Lernkartenset
Karte 1
Frage
What is water polarity?
Antwort
The unequal sharing of electrons in a water molecule, giving oxygen a partial negative charge and the hydrogens partial positive charges.
Karte 2
Frage
What is a hydrogen bond?
Antwort
A weak attraction between a partially positive hydrogen atom and a partially negative atom in another molecule.
Karte 3
Frage
What is cohesion?
Antwort
Attraction between molecules of the same substance.
Karte 4
Frage
What is adhesion?
Antwort
Attraction between molecules of different substances.
Karte 5
Frage
Which term describes unequal charge distribution within a water molecule?
Antwort
water polarity
Karte 6
Frage
Which term describes the intermolecular attraction that links neighboring water molecules?
Antwort
a hydrogen bond
Karte 7
Frage
Which term describes attraction between molecules of the same substance?
Antwort
cohesion
Karte 8
Frage
Which term describes attraction between water and a different material?
Antwort
adhesion
Karte 9
Frage
What is a solvent?
Antwort
A liquid that dissolves solutes to form a solution.
Karte 10
Frage
What is specific heat capacity?
Antwort
The energy required to raise the temperature of a unit mass of a substance by one degree.
Karte 11
Frage
What is latent heat of vaporization?
Antwort
The energy required to vaporize a specified amount of liquid without changing its temperature.
Karte 12
Frage
Why does ice float on liquid water?
Antwort
Hydrogen bonds hold water molecules in an open lattice in ice, making ice less dense than liquid water.
Karte 13
Frage
Which term describes a liquid that dissolves solutes?
Antwort
a solvent
Karte 14
Frage
Which term describes the energy needed to raise a unit mass by one degree?
Antwort
specific heat capacity
Karte 15
Frage
Which term describes the energy needed to vaporize a liquid without a temperature change?
Antwort
latent heat of vaporization
Karte 16
Frage
Which property of water makes sweating an effective cooling mechanism?
Antwort
Water absorbs substantial energy as it evaporates; the highest-energy molecules leave, carrying heat away from the skin.
Karte 17
Frage
Why does water resist rapid temperature change?
Antwort
Many hydrogen bonds must absorb energy before molecular motion increases substantially, giving water a high specific heat capacity.
Karte 18
Frage
How do cohesion and adhesion support water transport in narrow tubes?
Antwort
Cohesion keeps water molecules connected, while adhesion helps the water column cling to the tube wall.
Karte 19
Frage
How does water participate differently in hydrolysis and condensation?
Antwort
Hydrolysis consumes water to split a bond; condensation forms a bond and releases water.
Karte 20
Frage
How does floating ice protect aquatic life in winter?
Antwort
Surface ice insulates the liquid water below, slowing further heat loss and preventing the whole body of water from freezing rapidly.
Karte 21
Frage
Why is water effective for transporting many biological solutes?
Antwort
Its polarity allows ions and other polar molecules to become surrounded and dispersed in solution.
Karte 22
Frage
Why do nonpolar substances tend to cluster in water?
Antwort
Clustering reduces the nonpolar surface exposed to water, allowing more water molecules to maintain hydrogen-bond interactions.
Karte 23
Frage
What is a nucleotide?
Antwort
A nucleic-acid monomer made of a pentose sugar, a phosphate group, and a nitrogenous base.
Karte 24
Frage
What is a nucleoside?
Antwort
A nitrogenous base joined to a pentose sugar, without a phosphate group.
Karte 25
Frage
What is a phosphodiester bond?
Antwort
A covalent bond linking the phosphate of one nucleotide to the sugar of the next nucleotide.
Karte 26
Frage
What is DNA?
Antwort
A usually double-stranded nucleic acid that stores hereditary information in its base sequence.
Karte 27
Frage
Which term describes a sugar-phosphate-base monomer?
Antwort
a nucleotide
Karte 28
Frage
Which term describes a base joined to a sugar but no phosphate?
Antwort
a nucleoside
Karte 29
Frage
Which term describes the covalent linkage in a nucleic-acid sugar-phosphate backbone?
Antwort
a phosphodiester bond
Karte 30
Frage
Which term describes the nucleic acid that usually stores hereditary information?
Antwort
DNA
Karte 31
Frage
What is RNA?
Antwort
A usually single-stranded nucleic acid involved in expressing and regulating genetic information.
Karte 32
Frage
What are antiparallel DNA strands?
Antwort
Two DNA strands that run in opposite 5′ to 3′ directions.
Karte 33
Frage
What is complementary base pairing?
Antwort
Specific pairing in which adenine pairs with thymine in DNA, or uracil in RNA, and cytosine pairs with guanine.
Karte 34
Frage
What is a purine?
Antwort
A nitrogenous base with two fused rings; adenine and guanine are purines.
Karte 35
Frage
Which term describes the usually single-stranded nucleic acid used in gene expression?
Antwort
RNA
Karte 36
Frage
Which term describes DNA strands running in opposite directions?
Antwort
antiparallel DNA strands
Karte 37
Frage
Which term describes specific A–T or A–U and C–G pairing?
Antwort
complementary base pairing
Karte 38
Frage
Which term describes a two-ring nitrogenous base?
Antwort
a purine
Karte 39
Frage
What is a pyrimidine?
Antwort
A nitrogenous base with one ring; cytosine, thymine, and uracil are pyrimidines.
Karte 40
Frage
What is a genome?
Antwort
The complete genetic material of an organism or cell.
Karte 41
Frage
What three structural features commonly distinguish RNA from DNA?
Antwort
RNA usually contains ribose, uses uracil instead of thymine, and is single-stranded rather than double-stranded.
Karte 42
Frage
What determines the base sequence of the second DNA strand?
Antwort
Complementary base-pairing rules determine it: A pairs with T, and C pairs with G.
Karte 43
Frage
Which term describes a one-ring nitrogenous base?
Antwort
a pyrimidine
Karte 44
Frage
Which term describes the complete genetic material of an organism?
Antwort
a genome
Karte 45
Frage
What do the 5′ and 3′ labels of a nucleic-acid strand refer to?
Antwort
They refer to numbered carbon atoms in the pentose sugar and define the strand's chemical direction.
Karte 46
Frage
Where is genetic information encoded in DNA?
Antwort
In the order of nitrogenous bases along the DNA strand.
Karte 47
Frage
Why is ATP classified as a nucleotide?
Antwort
It contains adenine, ribose, and phosphate groups, the three component types of a nucleotide.
Karte 48
Frage
How do mRNA, tRNA, and rRNA contribute to protein synthesis?
Antwort
mRNA carries the coding sequence, tRNA delivers amino acids, and rRNA forms the catalytic and structural core of ribosomes.
Karte 49
Frage
How are a gene and a chromosome related?
Antwort
A gene is a DNA sequence with a biological function; a chromosome is one long DNA molecule containing many genes and other sequences.
Karte 50
Frage
What happens to double-stranded DNA when it is denatured by heat?
Antwort
Hydrogen bonds between complementary bases break and the two strands separate; the covalent backbones usually remain intact.
Karte 51
Frage
Why can each DNA strand serve as a template during replication?
Antwort
Its base sequence determines a complementary sequence through specific base pairing.
Karte 52
Frage
In which direction are new nucleic-acid strands synthesized?
Antwort
Nucleotides are added to the 3′ end, so synthesis proceeds 5′ to 3′.
Karte 53
Frage
What is a monosaccharide?
Antwort
A single sugar unit that can serve as a carbohydrate monomer.
Karte 54
Frage
What is a disaccharide?
Antwort
A carbohydrate formed from two monosaccharides joined by a glycosidic bond.
Karte 55
Frage
What is a polysaccharide?
Antwort
A polymer made from many monosaccharide units.
Karte 56
Frage
What is a glycosidic bond?
Antwort
A covalent bond joining monosaccharides in a carbohydrate.
Karte 57
Frage
Which term describes a single sugar unit?
Antwort
a monosaccharide
Karte 58
Frage
Which term describes two monosaccharides joined together?
Antwort
a disaccharide
Karte 59
Frage
Which term describes a polymer of many sugar units?
Antwort
a polysaccharide
Karte 60
Frage
Which term describes the covalent linkage between monosaccharides?
Antwort
a glycosidic bond
Karte 61
Frage
What is a triglyceride?
Antwort
A lipid formed from glycerol joined to three fatty acids.
Karte 62
Frage
What is a fatty acid?
Antwort
A hydrocarbon chain with a carboxyl group that can form part of many lipids.
Karte 63
Frage
What is a saturated fatty acid?
Antwort
A fatty acid with no carbon-carbon double bonds in its hydrocarbon chain.
Karte 64
Frage
What is a phospholipid?
Antwort
An amphipathic lipid with a phosphate-containing hydrophilic head and hydrophobic fatty-acid tails.
Karte 65
Frage
Which term describes glycerol joined to three fatty acids?
Antwort
a triglyceride
Karte 66
Frage
Which term describes a hydrocarbon chain ending in a carboxyl group?
Antwort
a fatty acid
Karte 67
Frage
Which term describes a fatty acid without carbon-carbon double bonds?
Antwort
a saturated fatty acid
Karte 68
Frage
Which term describes a lipid with a polar head and nonpolar tails?
Antwort
a phospholipid
Karte 69
Frage
How is a glycosidic bond formed between two monosaccharides?
Antwort
A condensation reaction joins them and releases a molecule of water.
Karte 70
Frage
How is a polysaccharide broken into smaller sugars?
Antwort
Hydrolysis adds water across glycosidic bonds, splitting the polymer.
Karte 71
Frage
Which polysaccharides store glucose in plants and animals?
Antwort
Starch stores glucose in plants; glycogen stores glucose in animals and fungi.
Karte 72
Frage
Why is cellulose suitable for plant cell walls?
Antwort
Its straight β-glucose chains hydrogen-bond into strong microfibrils that resist stretching.
Karte 73
Frage
Why do lipids store more energy per gram than carbohydrates?
Antwort
Lipids contain more energy-rich carbon-hydrogen bonds and are more reduced.
Karte 74
Frage
Why do phospholipids form bilayers in water?
Antwort
Hydrophilic heads interact with water while hydrophobic tails cluster away from water.
Karte 75
Frage
Besides energy storage, what are three biological roles of lipids?
Antwort
They form membranes, provide thermal insulation and cushioning, and can act as signaling molecules.
Karte 76
Frage
How do cis double bonds affect fatty-acid packing and melting point?
Antwort
They introduce bends that reduce close packing, usually lowering the melting point.
Karte 77
Frage
What is an amino acid?
Antwort
A protein monomer with an amino group, a carboxyl group, a hydrogen, and a variable R group attached to a central carbon.
Karte 78
Frage
What is a peptide bond?
Antwort
The covalent bond formed between the amino group of one amino acid and the carboxyl group of another.
Karte 79
Frage
What is a polypeptide?
Antwort
A chain of amino acids joined by peptide bonds.
Karte 80
Frage
What is protein primary structure?
Antwort
The amino-acid sequence of a polypeptide.
Karte 81
Frage
Which term describes a protein monomer with amino, carboxyl, and variable R groups?
Antwort
an amino acid
Karte 82
Frage
Which term describes the covalent linkage between amino acids?
Antwort
a peptide bond
Karte 83
Frage
Which term describes a chain of peptide-linked amino acids?
Antwort
a polypeptide
Karte 84
Frage
Which term describes a protein's amino-acid sequence?
Antwort
protein primary structure
Karte 85
Frage
What is protein secondary structure?
Antwort
Local folding such as α-helices and β-sheets stabilized mainly by backbone hydrogen bonds.
Karte 86
Frage
What is protein tertiary structure?
Antwort
The overall three-dimensional shape of one polypeptide produced by interactions among R groups and the backbone.
Karte 87
Frage
What is protein quaternary structure?
Antwort
The arrangement of multiple polypeptide subunits in one functional protein.
Karte 88
Frage
What is protein denaturation?
Antwort
Loss of a protein's normal three-dimensional shape and therefore usually its function.
Karte 89
Frage
Which term describes local α-helix and β-sheet folding?
Antwort
protein secondary structure
Karte 90
Frage
Which term describes the overall three-dimensional shape of one polypeptide?
Antwort
protein tertiary structure
Karte 91
Frage
Which term describes the association of multiple polypeptide subunits?
Antwort
protein quaternary structure
Karte 92
Frage
Which term describes loss of a protein's native shape?
Antwort
protein denaturation
Karte 93
Frage
What mainly gives different amino acids their different chemical properties?
Antwort
Their variable R groups.
Karte 94
Frage
What reaction forms a peptide bond?
Antwort
A condensation reaction releases water as the amino and carboxyl groups join.
Karte 95
Frage
Why can high temperature denature a protein?
Antwort
Increased molecular motion disrupts weak interactions that maintain the protein's shape.
Karte 96
Frage
Why can extreme pH denature a protein?
Antwort
It changes the charges of R groups and disrupts ionic and hydrogen-bond interactions.
Karte 97
Frage
How do fibrous and globular proteins generally differ?
Antwort
Fibrous proteins are elongated and mainly structural; globular proteins are compact and often perform dynamic functions.
Karte 98
Frage
Why is three-dimensional shape crucial to protein function?
Antwort
It creates specific binding, catalytic, structural, or interaction surfaces.
Karte 99
Frage
Name four broad biological roles of proteins.
Antwort
Catalysis, transport, signaling, defense, movement, and structural support are major roles; any four are sufficient.
Karte 100
Frage
How can changing one amino acid alter protein function?
Antwort
The substitution can change R-group interactions, folding, stability, or an active or binding site.
Karte 101
Frage
What is cell theory?
Antwort
The principles that living organisms are made of cells, cells are the basic units of life, and cells arise from pre-existing cells.
Karte 102
Frage
What is a prokaryotic cell?
Antwort
A cell without a nucleus or other membrane-bound organelles.
Karte 103
Frage
What is a eukaryotic cell?
Antwort
A cell with DNA enclosed in a nucleus and with membrane-bound organelles.
Karte 104
Frage
What is the nucleus?
Antwort
The double-membrane organelle that contains most of a eukaryotic cell's DNA.
Karte 105
Frage
Which term describes the principles describing cells as life's basic units?
Antwort
cell theory
Karte 106
Frage
Which term describes a cell lacking a nucleus and membrane-bound organelles?
Antwort
a prokaryotic cell
Karte 107
Frage
Which term describes a cell with a nucleus and membrane-bound organelles?
Antwort
a eukaryotic cell
Karte 108
Frage
Which term describes the organelle containing most eukaryotic DNA?
Antwort
the nucleus
Karte 109
Frage
What is a ribosome?
Antwort
A molecular complex of rRNA and proteins that synthesizes polypeptides.
Karte 110
Frage
What is the cytoplasm?
Antwort
The material inside the plasma membrane but outside the nucleus, including cytosol and organelles.
Karte 111
Frage
What is the plasma membrane?
Antwort
The selectively permeable boundary separating a cell from its environment.
Karte 112
Frage
What is a cell wall?
Antwort
A rigid extracellular layer that supports and protects cells in plants, fungi, and most prokaryotes.
Karte 113
Frage
Which term describes the complex that synthesizes polypeptides?
Antwort
a ribosome
Karte 114
Frage
Which term describes cell contents inside the plasma membrane but outside the nucleus?
Antwort
the cytoplasm
Karte 115
Frage
Which term describes the selectively permeable cell boundary?
Antwort
the plasma membrane
Karte 116
Frage
Which term describes a rigid extracellular support layer?
Antwort
a cell wall
Karte 117
Frage
What is the nucleoid?
Antwort
The non-membrane-bound region containing the main chromosome of a prokaryotic cell.
Karte 118
Frage
What is the cytoskeleton?
Antwort
A dynamic network of protein filaments involved in cell shape, transport, division, and movement.
Karte 119
Frage
What structures are shared by all cells?
Antwort
A plasma membrane, cytoplasm, genetic material, and ribosomes.
Karte 120
Frage
Which structures distinguish a typical plant cell from a typical animal cell?
Antwort
A plant cell has a cellulose wall, chloroplasts in photosynthetic tissues, and a large central vacuole; an animal cell lacks these.
Karte 121
Frage
Which term describes the prokaryotic chromosome-containing region?
Antwort
the nucleoid
Karte 122
Frage
Which term describes the internal network of protein filaments?
Antwort
the cytoskeleton
Karte 123
Frage
How is genetic material commonly organized in a prokaryotic cell?
Antwort
The main DNA is usually one circular chromosome in the nucleoid, often accompanied by smaller plasmids.
Karte 124
Frage
How is microscope magnification calculated?
Antwort
Magnification = image size ÷ actual size, using the same units.
Karte 125
Frage
What does microscope resolution describe?
Antwort
The ability to distinguish two close points as separate.
Karte 126
Frage
Arrange these from smallest to largest: ribosome, bacterium, animal cell.
Antwort
Ribosome, bacterium, animal cell.
Karte 127
Frage
How does the cytoskeleton support intracellular transport?
Antwort
Motor proteins move vesicles and other cargo along cytoskeletal filaments.
Karte 128
Frage
Why does a small cell usually exchange materials more efficiently than a geometrically similar large cell?
Antwort
It has a larger surface-area-to-volume ratio, providing more exchange surface per unit of cell contents.
Karte 129
Frage
Why is a cell more than a collection of isolated molecules?
Antwort
Organized interactions among components produce emergent functions such as metabolism, regulation, and reproduction.
Karte 130
Frage
What major advantage do membrane-bound organelles give eukaryotic cells?
Antwort
They separate incompatible reactions and create specialized local conditions.
Karte 131
Frage
What is a phospholipid bilayer?
Antwort
A double layer of phospholipids with hydrophilic heads facing water and hydrophobic tails facing inward.
Karte 132
Frage
What is the fluid mosaic model?
Antwort
A model describing membranes as mobile phospholipids containing a changing mosaic of proteins and other components.
Karte 133
Frage
What is an integral membrane protein?
Antwort
A protein embedded in the bilayer, often spanning it.
Karte 134
Frage
What is a peripheral membrane protein?
Antwort
A protein attached to a membrane surface rather than embedded in the bilayer.
Karte 135
Frage
Which term describes a double phospholipid layer with inward-facing tails?
Antwort
a phospholipid bilayer
Karte 136
Frage
Which term describes the model of a mobile lipid layer containing varied proteins?
Antwort
the fluid mosaic model
Karte 137
Frage
Which term describes a protein embedded within the lipid bilayer?
Antwort
an integral membrane protein
Karte 138
Frage
Which term describes a protein attached to a membrane surface?
Antwort
a peripheral membrane protein
Karte 139
Frage
What is membrane cholesterol?
Antwort
An amphipathic lipid that buffers membrane fluidity and reduces permeability in animal cells.
Karte 140
Frage
What is a glycoprotein?
Antwort
A protein with an attached carbohydrate chain, often used in recognition, adhesion, or signaling.
Karte 141
Frage
What is diffusion?
Antwort
Net movement of particles from a region of higher concentration to lower concentration due to random motion.
Karte 142
Frage
What is osmosis?
Antwort
Net movement of water across a selectively permeable membrane from higher water potential to lower water potential.
Karte 143
Frage
Which term describes the animal-membrane lipid that buffers fluidity?
Antwort
membrane cholesterol
Karte 144
Frage
Which term describes a carbohydrate-bearing protein?
Antwort
a glycoprotein
Karte 145
Frage
Which term describes net movement down a concentration gradient?
Antwort
diffusion
Karte 146
Frage
Which term describes net water movement across a selectively permeable membrane?
Antwort
osmosis
Karte 147
Frage
What is facilitated diffusion?
Antwort
Passive movement down a gradient through a membrane channel or carrier protein.
Karte 148
Frage
What is active transport?
Antwort
Energy-requiring movement of a substance against its concentration or electrochemical gradient.
Karte 149
Frage
Why is the phospholipid bilayer selectively permeable?
Antwort
Its hydrophobic interior allows small nonpolar molecules through more readily than ions and most large or polar molecules.
Karte 150
Frage
How do simple diffusion and facilitated diffusion differ?
Antwort
Both are passive, but facilitated diffusion uses specific membrane proteins while simple diffusion passes through the bilayer.
Karte 151
Frage
Which term describes passive transport through a channel or carrier?
Antwort
facilitated diffusion
Karte 152
Frage
Which term describes energy-dependent transport against a gradient?
Antwort
active transport
Karte 153
Frage
How do channel and carrier proteins differ?
Antwort
Channels provide hydrophilic pores; carriers bind solutes and change shape to move them.
Karte 154
Frage
How can an ATP-driven pump maintain an ion gradient?
Antwort
It couples ATP hydrolysis to a conformational change that moves ions against their electrochemical gradient.
Karte 155
Frage
How does endocytosis move material into a cell?
Antwort
The plasma membrane folds inward and pinches off a vesicle containing the material.
Karte 156
Frage
How does exocytosis move material out of a cell?
Antwort
An intracellular vesicle fuses with the plasma membrane and releases its contents outside.
Karte 157
Frage
What happens to an animal cell in a strongly hypotonic solution?
Antwort
Water enters by osmosis; without a cell wall, the cell may swell and lyse.
Karte 158
Frage
Does molecular movement stop when diffusion reaches equilibrium?
Antwort
No. Molecules continue moving randomly, but there is no net movement between regions.
Karte 159
Frage
How does decreasing temperature generally affect membrane fluidity?
Antwort
It reduces phospholipid movement and makes the membrane less fluid.
Karte 160
Frage
Why do unsaturated fatty-acid tails increase membrane fluidity?
Antwort
Their cis double-bond bends prevent phospholipids from packing tightly.
Karte 161
Frage
What changes increase the rate of simple diffusion across a membrane?
Antwort
A steeper gradient, larger surface area, higher temperature, shorter distance, and greater membrane permeability increase the rate.
Karte 162
Frage
What is a mitochondrion?
Antwort
A double-membrane organelle where most aerobic ATP production occurs.
Karte 163
Frage
What is a chloroplast?
Antwort
A double-membrane organelle where photosynthesis occurs in plants and algae.
Karte 164
Frage
What is rough endoplasmic reticulum?
Antwort
A membrane network bearing ribosomes that synthesizes and begins processing many secreted and membrane proteins.
Karte 165
Frage
What is smooth endoplasmic reticulum?
Antwort
A membrane network involved in lipid synthesis, detoxification, and calcium storage.
Karte 166
Frage
Which term describes the main organelle of aerobic ATP production?
Antwort
a mitochondrion
Karte 167
Frage
Which term describes the photosynthetic organelle of plants and algae?
Antwort
a chloroplast
Karte 168
Frage
Which term describes the ribosome-studded membrane network?
Antwort
rough endoplasmic reticulum
Karte 169
Frage
Which term describes the membrane network that lacks ribosomes and synthesizes lipids?
Antwort
smooth endoplasmic reticulum
Karte 170
Frage
What is the Golgi apparatus?
Antwort
Stacked membranes that modify, sort, and package proteins and lipids into vesicles.
Karte 171
Frage
What is a lysosome?
Antwort
An acidic enzyme-containing organelle that digests macromolecules and worn cellular components.
Karte 172
Frage
What is a vesicle?
Antwort
A small membrane-bound compartment used for transport, storage, or chemical reactions.
Karte 173
Frage
What is the central vacuole?
Antwort
A large plant-cell compartment that stores solutes and helps maintain turgor pressure.
Karte 174
Frage
Which term describes the organelle that modifies and sorts cellular cargo?
Antwort
the Golgi apparatus
Karte 175
Frage
Which term describes the acidic digestive organelle?
Antwort
a lysosome
Karte 176
Frage
Which term describes a small membrane-bound transport compartment?
Antwort
a vesicle
Karte 177
Frage
Which term describes the large plant compartment that supports turgor?
Antwort
the central vacuole
Karte 178
Frage
Why can compartmentalization increase metabolic efficiency?
Antwort
It concentrates enzymes and substrates, maintains suitable local conditions, and separates incompatible reactions.
Karte 179
Frage
How do mitochondrial cristae support ATP production?
Antwort
They increase inner-membrane area for electron transport chains and ATP synthase.
Karte 180
Frage
Why are chloroplast thylakoids arranged as extensive membranes?
Antwort
They provide a large surface for light-absorbing complexes, electron transport chains, and ATP synthase.
Karte 181
Frage
What is the main function of the nucleolus?
Antwort
It produces rRNA and assembles ribosomal subunits.
Karte 182
Frage
Trace a secreted protein from synthesis to release.
Antwort
Ribosome on rough ER → ER lumen → transport vesicle → Golgi apparatus → secretory vesicle → plasma membrane → exocytosis.
Karte 183
Frage
Why does a lysosome maintain an acidic interior?
Antwort
Its hydrolytic enzymes work best at low pH, and acidity helps confine their activity from the cytosol.
Karte 184
Frage
How do the nucleus, ribosomes, ER, and Golgi cooperate in protein production?
Antwort
DNA instructions are transcribed in the nucleus; ribosomes translate them; ER folds or modifies many products; Golgi further modifies and sorts them.
Karte 185
Frage
How are transport vesicles directed to the correct target membrane?
Antwort
Specific recognition proteins on vesicles and target membranes interact, allowing selective docking and fusion.
Karte 186
Frage
What is cell differentiation?
Antwort
The process by which a cell develops specialized structure and function.
Karte 187
Frage
What is a stem cell?
Antwort
An unspecialized cell able to self-renew and produce differentiated cells.
Karte 188
Frage
What is gene expression?
Antwort
Use of genetic information to produce a functional RNA or protein product.
Karte 189
Frage
What is a tissue?
Antwort
A coordinated group of similar or related cells performing a shared function.
Karte 190
Frage
Which term describes development of specialized cell structure and function?
Antwort
cell differentiation
Karte 191
Frage
Which term describes an unspecialized self-renewing cell?
Antwort
a stem cell
Karte 192
Frage
Which term describes production of a functional product from genetic information?
Antwort
gene expression
Karte 193
Frage
Which term describes a group of coordinated cells with a shared function?
Antwort
a tissue
Karte 194
Frage
What is an organ?
Antwort
A structure made of multiple tissues working together for particular functions.
Karte 195
Frage
What is the organ-system level of biological organization?
Antwort
A group of organs that coordinate to perform major functions for an organism.
Karte 196
Frage
What is surface-area-to-volume ratio?
Antwort
The amount of surface area available relative to the volume it must serve.
Karte 197
Frage
How can two specialized cells have the same genome but different structures?
Antwort
They express different sets and amounts of genes, producing different proteins and cellular features.
Karte 198
Frage
Which term describes a structure composed of multiple tissue types?
Antwort
an organ
Karte 199
Frage
Which term describes the level of biological organization formed by coordinated organs?
Antwort
an organ system
Karte 200
Frage
Which term describes surface area available per unit volume?
Antwort
surface-area-to-volume ratio
Karte 201
Frage
How is a mammalian red blood cell specialized for oxygen transport?
Antwort
Its biconcave shape increases exchange area, it is flexible, and loss of its nucleus leaves more space for hemoglobin.
Karte 202
Frage
How is a sperm cell specialized for fertilization?
Antwort
It has a flagellum for movement, many mitochondria for ATP, a haploid nucleus, and an acrosome containing enzymes.
Karte 203
Frage
How is a neuron specialized for rapid communication?
Antwort
Long processes carry signals over distance, branching dendrites receive inputs, and synaptic terminals transmit signals to other cells.
Karte 204
Frage
How is a root hair cell specialized for mineral and water uptake?
Antwort
Its long projection increases surface area, its thin wall shortens the pathway, and membrane transport proteins take up ions.
Karte 205
Frage
How is a palisade mesophyll cell specialized for photosynthesis?
Antwort
It contains many chloroplasts and is positioned near the upper leaf surface where light is strongest.
Karte 206
Frage
How do ciliated epithelial cells help protect airways?
Antwort
Their cilia move mucus containing trapped particles and microbes toward the throat.
Karte 207
Frage
Why can extreme specialization reduce a cell's independence?
Antwort
Resources and structures are committed to a narrow role, so the cell depends on other cells for functions it no longer performs well.
Karte 208
Frage
What is water potential?
Antwort
The potential energy of water per unit volume relative to pure water, used to predict the direction of water movement.
Karte 209
Frage
What is solute potential?
Antwort
The negative contribution of dissolved solutes to water potential.
Karte 210
Frage
What is pressure potential?
Antwort
The contribution of physical pressure to water potential.
Karte 211
Frage
What is turgor pressure?
Antwort
Outward pressure of a plant-cell interior against its cell wall after water uptake.
Karte 212
Frage
Which term describes the tendency of water to move relative to pure water?
Antwort
water potential
Karte 213
Frage
Which term describes the water-potential component lowered by dissolved solutes?
Antwort
solute potential
Karte 214
Frage
Which term describes the water-potential component caused by physical pressure?
Antwort
pressure potential
Karte 215
Frage
Which term describes pressure of plant-cell contents against the wall?
Antwort
turgor pressure
Karte 216
Frage
What is plasmolysis?
Antwort
Separation of the plasma membrane from the cell wall after a plant cell loses water.
Karte 217
Frage
What is a flaccid plant cell?
Antwort
A plant cell with insufficient turgor pressure to be firm.
Karte 218
Frage
What is an isotonic condition?
Antwort
A condition in which two solutions have equal effective water potential and no net water movement occurs.
Karte 219
Frage
In which direction does water move across a permeable membrane?
Antwort
From higher water potential to lower water potential.
Karte 220
Frage
Which term describes membrane separation from the plant cell wall after water loss?
Antwort
plasmolysis
Karte 221
Frage
Which term describes a plant cell lacking firm turgor?
Antwort
a flaccid plant cell
Karte 222
Frage
Which term describes equal effective water potential across a membrane?
Antwort
an isotonic condition
Karte 223
Frage
What is the water potential of pure water at standard pressure?
Antwort
Zero; adding solute makes water potential more negative.
Karte 224
Frage
How are water potential, solute potential, and pressure potential related?
Antwort
Water potential equals solute potential plus pressure potential: Ψ = Ψs + Ψp.
Karte 225
Frage
Why does a plant cell usually become turgid rather than burst in a hypotonic solution?
Antwort
Water entry raises pressure potential, while the rigid cell wall resists further expansion.
Karte 226
Frage
What happens to a plant cell placed in a solution with much lower water potential?
Antwort
Water leaves the cell, turgor falls, and severe loss can cause plasmolysis.
Karte 227
Frage
Can two solutions have different solute concentrations but equal water potential?
Antwort
Yes. A difference in pressure potential can offset a difference in solute potential.
Karte 228
Frage
What is an enzyme?
Antwort
A biological catalyst that increases reaction rate without being consumed.
Karte 229
Frage
What is an active site?
Antwort
The region of an enzyme where substrate binds and catalysis occurs.
Karte 230
Frage
What is a substrate?
Antwort
A reactant molecule on which an enzyme acts.
Karte 231
Frage
What is activation energy?
Antwort
The minimum energy input needed for a reaction to begin.
Karte 232
Frage
Which term describes a biological catalyst?
Antwort
an enzyme
Karte 233
Frage
Which term describes the substrate-binding catalytic region of an enzyme?
Antwort
an active site
Karte 234
Frage
Which term describes a reactant bound and changed by an enzyme?
Antwort
a substrate
Karte 235
Frage
Which term describes the energy barrier that must be overcome for a reaction?
Antwort
activation energy
Karte 236
Frage
What is the induced-fit model?
Antwort
The model in which substrate binding changes active-site shape to improve catalytic interactions.
Karte 237
Frage
What is enzyme denaturation?
Antwort
Loss of the active three-dimensional shape of an enzyme, usually causing loss of activity.
Karte 238
Frage
What is competitive inhibition?
Antwort
Inhibition caused by a molecule competing with substrate for the active site.
Karte 239
Frage
What is noncompetitive inhibition?
Antwort
Inhibition caused by binding away from the active site and reducing catalytic function.
Karte 240
Frage
Which term describes the model where substrate binding reshapes the active site?
Antwort
the induced-fit model
Karte 241
Frage
Which term describes loss of an enzyme's functional shape?
Antwort
enzyme denaturation
Karte 242
Frage
Which term describes inhibition by active-site competition?
Antwort
competitive inhibition
Karte 243
Frage
Which term describes inhibition by binding outside the active site?
Antwort
noncompetitive inhibition
Karte 244
Frage
What is an enzyme optimum?
Antwort
The condition, such as temperature or pH, at which an enzyme's activity is highest.
Karte 245
Frage
What is feedback inhibition?
Antwort
Control in which a pathway product inhibits an enzyme acting earlier in the pathway.
Karte 246
Frage
How does an enzyme increase reaction rate?
Antwort
It stabilizes the transition state and provides a pathway with lower activation energy.
Karte 247
Frage
Why does enzyme activity often rise and then fall as temperature increases?
Antwort
Molecular collisions initially increase, but excessive heat disrupts enzyme shape and denatures the active site.
Karte 248
Frage
Which term describes the condition producing maximum enzyme activity?
Antwort
an enzyme optimum
Karte 249
Frage
Which term describes pathway control by inhibition from an end product?
Antwort
feedback inhibition
Karte 250
Frage
Why does each enzyme have a characteristic pH range?
Antwort
pH changes the ionization of amino-acid side chains, affecting active-site shape and chemical interactions.
Karte 251
Frage
Why does increasing substrate concentration eventually stop increasing enzyme rate?
Antwort
At saturation, nearly all active sites are occupied and enzyme concentration limits the maximum rate.
Karte 252
Frage
How does increasing enzyme concentration affect rate when substrate is abundant?
Antwort
More active sites are available, so the initial rate increases roughly in proportion to enzyme concentration.
Karte 253
Frage
What gives an enzyme substrate specificity?
Antwort
The active site's shape, charge, polarity, and chemical groups complement particular substrates and transition states.
Karte 254
Frage
What is one practical advantage of immobilizing an enzyme?
Antwort
The enzyme can be separated from products and reused while conditions around it are controlled.
Karte 255
Frage
Does an enzyme change a reaction's equilibrium position?
Antwort
No. It speeds forward and reverse reactions but does not change the equilibrium constant or final equilibrium position.
Karte 256
Frage
How can high substrate concentration reduce competitive inhibition?
Antwort
More substrate molecules increase the chance that substrate rather than inhibitor occupies the active site.
Karte 257
Frage
Why are metabolic reactions commonly organized into pathways?
Antwort
A sequence of enzyme-controlled steps allows energy changes and intermediates to be controlled and coupled.
Karte 258
Frage
What is ATP?
Antwort
A nucleotide that transfers usable energy through coupling of its hydrolysis to cellular processes.
Karte 259
Frage
What is cellular respiration?
Antwort
Controlled release of energy from organic molecules to produce ATP.
Karte 260
Frage
What is glycolysis?
Antwort
A cytosolic pathway that splits glucose into two pyruvate molecules and yields a small amount of ATP and reduced electron carriers.
Karte 261
Frage
What is pyruvate?
Antwort
The three-carbon product of glycolysis that can enter aerobic or anaerobic pathways.
Karte 262
Frage
Which term describes the cell's immediate phosphoryl-group energy carrier?
Antwort
ATP
Karte 263
Frage
Which term describes controlled ATP-producing breakdown of organic molecules?
Antwort
cellular respiration
Karte 264
Frage
Which term describes the cytosolic splitting of glucose into pyruvate?
Antwort
glycolysis
Karte 265
Frage
Which term describes the three-carbon product of glycolysis?
Antwort
pyruvate
Karte 266
Frage
What is aerobic respiration?
Antwort
Respiration that uses oxygen as the final electron acceptor and produces much more ATP than fermentation.
Karte 267
Frage
What is anaerobic metabolism?
Antwort
ATP-producing metabolism that proceeds without oxygen.
Karte 268
Frage
What is fermentation?
Antwort
An anaerobic pathway that regenerates oxidized electron carriers so glycolysis can continue.
Karte 269
Frage
What is oxidation?
Antwort
Loss of electrons, often accompanied in biology by loss of hydrogen or gain of oxygen.
Karte 270
Frage
Which term describes respiration using oxygen as final electron acceptor?
Antwort
aerobic respiration
Karte 271
Frage
Which term describes ATP-producing metabolism without oxygen?
Antwort
anaerobic metabolism
Karte 272
Frage
Which term describes anaerobic regeneration of electron carriers after glycolysis?
Antwort
fermentation
Karte 273
Frage
Which term describes loss of electrons?
Antwort
oxidation
Karte 274
Frage
What is reduction?
Antwort
Gain of electrons, often accompanied in biology by gain of hydrogen or loss of oxygen.
Karte 275
Frage
What is a reduced electron carrier?
Antwort
A molecule such as NADH that carries high-energy electrons and hydrogen from one reaction to another.
Karte 276
Frage
What is chemiosmosis?
Antwort
ATP production driven by ions moving down an electrochemical gradient through ATP synthase.
Karte 277
Frage
What is the overall word equation for aerobic respiration of glucose?
Antwort
Glucose + oxygen → carbon dioxide + water + energy transferred to ATP and heat.
Karte 278
Frage
Which term describes gain of electrons?
Antwort
reduction
Karte 279
Frage
Which term describes a molecule carrying high-energy electrons between reactions?
Antwort
a reduced electron carrier
Karte 280
Frage
Which term describes ATP production powered by an ion gradient?
Antwort
chemiosmosis
Karte 281
Frage
Where does glycolysis occur?
Antwort
In the cytosol.
Karte 282
Frage
What major stages of aerobic respiration occur in mitochondria?
Antwort
Pyruvate oxidation and the citric acid cycle occur in the matrix; electron transport and chemiosmosis occur at the inner membrane.
Karte 283
Frage
What is oxygen's direct role in aerobic respiration?
Antwort
It accepts electrons and hydrogen ions at the end of the electron transport chain, forming water.
Karte 284
Frage
Why does aerobic respiration yield much more ATP per glucose than fermentation?
Antwort
It transfers electrons through an electron transport chain and uses oxidative phosphorylation, extracting far more of glucose's energy.
Karte 285
Frage
What is the purpose of lactate formation in oxygen-limited animal cells?
Antwort
It regenerates NAD⁺ so glycolysis can continue producing a small amount of ATP.
Karte 286
Frage
What products are formed during alcoholic fermentation in yeast?
Antwort
Ethanol and carbon dioxide, while NAD⁺ is regenerated.
Karte 287
Frage
Why is some energy released by respiration transferred as heat rather than captured in ATP?
Antwort
Energy conversions are not fully efficient, so part of the chemical energy becomes disordered molecular motion.
Karte 288
Frage
What is substrate-level phosphorylation?
Antwort
Direct transfer of a phosphate group from a metabolic intermediate to ADP to form ATP.
Karte 289
Frage
How does electron transport lead to ATP synthesis in mitochondria?
Antwort
Electron energy pumps protons across the inner membrane; proton flow back through ATP synthase drives ATP formation.
Karte 290
Frage
Why can intense exercise increase lactate production?
Antwort
ATP demand can exceed oxygen delivery and aerobic capacity, so cells regenerate NAD⁺ through lactate formation to sustain glycolysis.
Karte 291
Frage
What is photosynthesis?
Antwort
Conversion of light energy into chemical energy used to synthesize organic molecules from carbon dioxide.
Karte 292
Frage
What is chlorophyll?
Antwort
A green pigment that absorbs light energy for photosynthesis.
Karte 293
Frage
What is an absorption spectrum?
Antwort
A graph showing how strongly a pigment absorbs different wavelengths of light.
Karte 294
Frage
What is an action spectrum?
Antwort
A graph showing the rate or effectiveness of photosynthesis at different wavelengths.
Karte 295
Frage
Which term describes light-driven synthesis of organic molecules from carbon dioxide?
Antwort
photosynthesis
Karte 296
Frage
Which term describes the principal green photosynthetic pigment?
Antwort
chlorophyll
Karte 297
Frage
Which term describes a graph of pigment absorption versus wavelength?
Antwort
an absorption spectrum
Karte 298
Frage
Which term describes a graph of photosynthetic effectiveness versus wavelength?
Antwort
an action spectrum
Karte 299
Frage
What is photolysis of water?
Antwort
Light-driven splitting of water that supplies electrons and hydrogen ions and releases oxygen.
Karte 300
Frage
What are light-dependent reactions?
Antwort
Photosynthetic reactions that use light to generate ATP and reduced electron carriers while releasing oxygen.
Karte 301
Frage
What is the Calvin cycle?
Antwort
A set of chloroplast reactions that uses ATP and reduced electron carriers to convert carbon dioxide into carbohydrate precursors.
Karte 302
Frage
What is carbon fixation?
Antwort
Incorporation of inorganic carbon dioxide into an organic molecule.
Karte 303
Frage
Which term describes light-driven splitting of water?
Antwort
photolysis of water
Karte 304
Frage
Which term describes photosynthetic reactions that directly capture light energy?
Antwort
light-dependent reactions
Karte 305
Frage
Which term describes the carbon-reduction cycle of photosynthesis?
Antwort
the Calvin cycle
Karte 306
Frage
Which term describes incorporation of carbon dioxide into organic matter?
Antwort
carbon fixation
Karte 307
Frage
What is the role of a stoma in photosynthesis?
Antwort
A pore in the leaf epidermis that regulates carbon-dioxide entry as well as water loss.
Karte 308
Frage
What is a limiting factor of photosynthesis?
Antwort
The environmental factor whose availability currently restricts the photosynthetic rate.
Karte 309
Frage
What is the light compensation point?
Antwort
The light intensity at which photosynthetic carbon uptake equals respiratory carbon release.
Karte 310
Frage
What is the overall word equation for oxygenic photosynthesis?
Antwort
Carbon dioxide + water → carbohydrate + oxygen, using light energy.
Karte 311
Frage
Which term describes the regulated leaf pore controlling carbon-dioxide entry for photosynthesis?
Antwort
a stoma
Karte 312
Frage
Which term describes the factor currently restricting photosynthetic rate?
Antwort
a limiting factor
Karte 313
Frage
Which term describes the light level where photosynthesis and respiration balance?
Antwort
the light compensation point
Karte 314
Frage
Where do the main stages of photosynthesis occur in a chloroplast?
Antwort
Light-dependent reactions occur in thylakoid membranes; carbon-fixation reactions occur in the stroma.
Karte 315
Frage
What energy conversion occurs during photosynthesis?
Antwort
Light energy is converted into chemical energy stored first in ATP and reduced carriers and ultimately in organic molecules.
Karte 316
Frage
From which reactant does the oxygen released by photosynthesis originate?
Antwort
Water.
Karte 317
Frage
What role does RuBisCO play in photosynthesis?
Antwort
It catalyzes fixation of carbon dioxide by adding it to an organic acceptor molecule.
Karte 318
Frage
What tradeoff is controlled when stomata open?
Antwort
Opening permits carbon dioxide entry but increases water loss by transpiration.
Karte 319
Frage
Name three leaf features that support photosynthesis.
Antwort
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.
Karte 320
Frage
What can a plant do with carbohydrate made by photosynthesis?
Antwort
Use it in respiration, convert it to storage or structural carbohydrates, or use its carbon to make lipids, amino acids, and other molecules.
Karte 321
Frage
How are products of the light-dependent reactions used in carbon fixation?
Antwort
ATP supplies energy and NADPH supplies reducing power for conversion of fixed carbon into carbohydrate precursors.
Karte 322
Frage
Why does increasing light intensity eventually stop increasing photosynthetic rate?
Antwort
Another factor, such as carbon dioxide supply, temperature, or biochemical capacity, becomes limiting.
Karte 323
Frage
How can increasing carbon dioxide concentration affect photosynthetic rate?
Antwort
It can increase the rate until another factor becomes limiting.
Karte 324
Frage
Why does photosynthetic rate usually have a temperature optimum?
Antwort
Enzyme-controlled reactions accelerate with temperature up to an optimum, then decline as enzymes and membranes lose effective function.
Karte 325
Frage
Why does an action spectrum broadly resemble the combined absorption spectra of photosynthetic pigments?
Antwort
Wavelengths absorbed by the pigments supply more energy for photosynthesis than poorly absorbed wavelengths.
Karte 326
Frage
What is semiconservative replication?
Antwort
DNA replication in which each daughter molecule contains one parental strand and one newly synthesized strand.
Karte 327
Frage
What is DNA helicase?
Antwort
An enzyme that unwinds the double helix and separates the strands by disrupting base pairing.
Karte 328
Frage
What is DNA polymerase?
Antwort
An enzyme that adds nucleotides to a growing DNA strand using a template.
Karte 329
Frage
What is a primer?
Antwort
A short nucleic-acid segment providing a free 3′ end from which DNA polymerase can extend.
Karte 330
Frage
Which term describes replication producing one old and one new strand per DNA molecule?
Antwort
semiconservative replication
Karte 331
Frage
Which term describes the enzyme that separates DNA strands?
Antwort
DNA helicase
Karte 332
Frage
Which term describes the enzyme that builds DNA from a template?
Antwort
DNA polymerase
Karte 333
Frage
Which term describes the short segment providing a starting 3′ end?
Antwort
a primer
Karte 334
Frage
What is the leading strand?
Antwort
The new DNA strand synthesized continuously toward the replication fork.
Karte 335
Frage
What is the lagging strand?
Antwort
The new DNA strand synthesized discontinuously away from the replication fork.
Karte 336
Frage
What is an Okazaki fragment?
Antwort
A short DNA segment synthesized on the lagging strand.
Karte 337
Frage
What is DNA ligase?
Antwort
An enzyme that seals breaks in the sugar-phosphate backbone, joining DNA fragments.
Karte 338
Frage
Which term describes the continuously synthesized daughter strand?
Antwort
the leading strand
Karte 339
Frage
Which term describes the discontinuously synthesized daughter strand?
Antwort
the lagging strand
Karte 340
Frage
Which term describes a short newly made segment of lagging-strand DNA?
Antwort
an Okazaki fragment
Karte 341
Frage
Which term describes the enzyme that joins DNA fragments by sealing the backbone?
Antwort
DNA ligase
Karte 342
Frage
How does complementary base pairing ensure accurate DNA copying?
Antwort
Each template base specifies the nucleotide added opposite it: A pairs with T, and C pairs with G.
Karte 343
Frage
Why does DNA polymerase synthesize DNA only 5′ to 3′?
Antwort
It can add a nucleotide only to the free 3′ hydroxyl group of the growing strand.
Karte 344
Frage
When in the cell cycle is nuclear DNA replicated?
Antwort
During S phase of interphase, before cell division.
Karte 345
Frage
How can a replication error become a permanent mutation?
Antwort
If it escapes proofreading and repair, the altered sequence can be copied in later cell generations.
Karte 346
Frage
Why are leading and lagging strands synthesized differently?
Antwort
The templates are antiparallel while DNA polymerase works only 5′ to 3′, forcing one strand to be made discontinuously.
Karte 347
Frage
How do proofreading and repair reduce replication errors?
Antwort
Incorrectly paired nucleotides are recognized, removed, and replaced before or after replication continues.
Karte 348
Frage
What three repeating steps amplify DNA in PCR?
Antwort
Strand separation by heating, primer annealing during cooling, and DNA extension by a heat-stable polymerase.
Karte 349
Frage
What determines which DNA region PCR amplifies?
Antwort
The sequences and positions of the two primers flanking the target region.
Karte 350
Frage
What is transcription?
Antwort
Synthesis of RNA from a DNA template.
Karte 351
Frage
What is RNA polymerase?
Antwort
The enzyme that synthesizes RNA complementary to a DNA template strand.
Karte 352
Frage
What is messenger RNA?
Antwort
RNA carrying a coding sequence from DNA to ribosomes.
Karte 353
Frage
What is a codon?
Antwort
A three-base sequence in mRNA that specifies an amino acid or a translation signal.
Karte 354
Frage
Which term describes RNA synthesis from DNA?
Antwort
transcription
Karte 355
Frage
Which term describes the enzyme that builds RNA from a DNA template?
Antwort
RNA polymerase
Karte 356
Frage
Which term describes RNA that carries coding information to ribosomes?
Antwort
messenger RNA
Karte 357
Frage
Which term describes a three-base mRNA unit?
Antwort
a codon
Karte 358
Frage
What is translation?
Antwort
Synthesis of a polypeptide using the codon sequence of mRNA.
Karte 359
Frage
What does a ribosome do during translation?
Antwort
It reads mRNA and catalyzes polypeptide synthesis using its rRNA-protein machinery.
Karte 360
Frage
What is transfer RNA?
Antwort
RNA that carries a specific amino acid and pairs its anticodon with an mRNA codon.
Karte 361
Frage
What is an anticodon?
Antwort
A three-base tRNA sequence complementary to an mRNA codon.
Karte 362
Frage
Which term describes polypeptide synthesis from an mRNA sequence?
Antwort
translation
Karte 363
Frage
Which term describes the translation complex that reads mRNA and builds a polypeptide?
Antwort
a ribosome
Karte 364
Frage
Which term describes the adaptor RNA carrying an amino acid?
Antwort
transfer RNA
Karte 365
Frage
Which term describes the tRNA triplet that pairs with a codon?
Antwort
an anticodon
Karte 366
Frage
What is the genetic code?
Antwort
The set of rules relating mRNA codons to amino acids and translation signals.
Karte 367
Frage
What are start and stop codons?
Antwort
mRNA signals that establish the reading frame or terminate translation.
Karte 368
Frage
Where do transcription and translation occur in a eukaryotic cell?
Antwort
Transcription occurs in the nucleus; translation occurs on ribosomes in the cytoplasm or on rough ER.
Karte 369
Frage
How is an mRNA sequence related to its DNA template strand?
Antwort
It is complementary and antiparallel, with uracil in RNA opposite adenine in DNA.
Karte 370
Frage
Which term describes the codon-to-amino-acid rule set?
Antwort
the genetic code
Karte 371
Frage
Which term describes codons that begin or end translation?
Antwort
start and stop codons
Karte 372
Frage
What reaction does the ribosome catalyze as a polypeptide grows?
Antwort
Formation of peptide bonds between adjacent amino acids.
Karte 373
Frage
What does it mean that the genetic code is degenerate?
Antwort
Most amino acids are specified by more than one codon.
Karte 374
Frage
How can one mRNA produce many polypeptides quickly?
Antwort
Multiple ribosomes can translate the same mRNA simultaneously as a polyribosome.
Karte 375
Frage
Why is translation not the final step in producing many functional proteins?
Antwort
The polypeptide must fold and may undergo cleavage, chemical modification, or assembly with other subunits.
Karte 376
Frage
How does mRNA compare with the DNA coding strand?
Antwort
It has the same base sequence except that RNA contains uracil where DNA contains thymine.
Karte 377
Frage
What happens during eukaryotic RNA splicing?
Antwort
Introns are removed and exons are joined to form mature mRNA.
Karte 378
Frage
Why must codons be read in the correct reading frame?
Antwort
Changing the starting position changes every downstream triplet and therefore the amino-acid sequence.
Karte 379
Frage
How is the correct amino acid matched to each mRNA codon?
Antwort
Each tRNA is charged with a particular amino acid, and its anticodon pairs with the complementary codon.
Karte 380
Frage
How can a base substitution affect a protein?
Antwort
It may be silent, change one amino acid, create a stop codon, or sometimes alter RNA processing.
Karte 381
Frage
What is a mutation?
Antwort
A change in a DNA sequence or chromosome structure that can be passed to daughter cells.
Karte 382
Frage
What is a base substitution?
Antwort
Replacement of one nucleotide pair by another.
Karte 383
Frage
What is an insertion mutation?
Antwort
Addition of one or more nucleotides to a DNA sequence.
Karte 384
Frage
What is a deletion mutation?
Antwort
Loss of one or more nucleotides from a DNA sequence.
Karte 385
Frage
Which term describes a lasting DNA-sequence or chromosome change?
Antwort
a mutation
Karte 386
Frage
Which term describes replacement of one DNA base pair?
Antwort
a base substitution
Karte 387
Frage
Which term describes addition of nucleotides to DNA?
Antwort
an insertion mutation
Karte 388
Frage
Which term describes loss of nucleotides from DNA?
Antwort
a deletion mutation
Karte 389
Frage
What is a frameshift mutation?
Antwort
A coding-sequence insertion or deletion not divisible by three that changes downstream codon grouping.
Karte 390
Frage
What is a silent mutation?
Antwort
A sequence change that does not alter the encoded amino acid.
Karte 391
Frage
What is a missense mutation?
Antwort
A mutation that changes a codon so a different amino acid is incorporated.
Karte 392
Frage
What is a nonsense mutation?
Antwort
A mutation that changes an amino-acid codon into a stop codon.
Karte 393
Frage
Which term describes a mutation that shifts downstream codon grouping?
Antwort
a frameshift mutation
Karte 394
Frage
Which term describes a coding change that leaves the amino acid unchanged?
Antwort
a silent mutation
Karte 395
Frage
Which term describes a mutation causing one amino-acid substitution?
Antwort
a missense mutation
Karte 396
Frage
Which term describes a mutation creating a premature stop codon?
Antwort
a nonsense mutation
Karte 397
Frage
How do germline and somatic mutations differ in inheritance?
Antwort
Germline mutations can enter gametes and be inherited; somatic mutations affect a cell lineage within the individual.
Karte 398
Frage
What can cause mutations?
Antwort
Replication errors, spontaneous chemical changes, radiation, and mutagenic chemicals can alter DNA.
Karte 399
Frage
How does DNA repair protect genome stability?
Antwort
Repair systems detect damaged or mismatched DNA and restore the correct structure or sequence when possible.
Karte 400
Frage
Why are mutations essential to evolution despite often being neutral or harmful?
Antwort
They create new alleles, providing the heritable variation on which selection and drift act.
Karte 401
Frage
What is the basic role of guide RNA in CRISPR gene editing?
Antwort
It directs a nuclease to a complementary DNA sequence.
Karte 402
Frage
Why can the same type of DNA mutation have effects ranging from none to severe?
Antwort
Effects depend on location, genetic-code redundancy, protein role, cell type, and environmental context.
Karte 403
Frage
How can accumulated mutations contribute to cancer?
Antwort
Mutations can activate growth-promoting genes or disable genes that restrain division, repair DNA, or trigger cell death.
Karte 404
Frage
Why can repairing a CRISPR-induced DNA break produce different editing outcomes?
Antwort
Different cellular repair pathways may disrupt the target sequence or use a supplied template for a specific change.
Karte 405
Frage
What is an off-target effect in gene editing?
Antwort
An unintended DNA change at a site sufficiently similar to the intended target.
Karte 406
Frage
Why does heritable human genome editing raise additional ethical concerns?
Antwort
Changes could pass to future generations who cannot consent, with uncertain long-term biological and social effects.
Karte 407
Frage
What is the cell cycle?
Antwort
The ordered sequence of cell growth, DNA replication, nuclear division, and cell division.
Karte 408
Frage
What is interphase?
Antwort
The period of growth, normal activity, and DNA replication between nuclear divisions.
Karte 409
Frage
What is mitosis?
Antwort
Nuclear division that usually produces genetically equivalent daughter nuclei.
Karte 410
Frage
What is cytokinesis?
Antwort
Division of the cytoplasm to form separate daughter cells.
Karte 411
Frage
Which term describes the ordered sequence from one cell division to the next?
Antwort
the cell cycle
Karte 412
Frage
Which term describes the growth and DNA-replication period between divisions?
Antwort
interphase
Karte 413
Frage
Which term describes division producing genetically equivalent nuclei?
Antwort
mitosis
Karte 414
Frage
Which term describes physical division of the cytoplasm?
Antwort
cytokinesis
Karte 415
Frage
What is a chromosome?
Antwort
One DNA molecule packaged with associated proteins.
Karte 416
Frage
What are sister chromatids?
Antwort
The two replicated copies of a chromosome joined before separation.
Karte 417
Frage
What is a centromere?
Antwort
The chromosome region that holds sister chromatids together and organizes kinetochore attachment.
Karte 418
Frage
What is the mitotic spindle?
Antwort
A microtubule system that attaches to and separates chromosomes during cell division.
Karte 419
Frage
Which term describes a protein-packaged DNA molecule?
Antwort
a chromosome
Karte 420
Frage
Which term describes joined replicated copies of one chromosome?
Antwort
sister chromatids
Karte 421
Frage
Which term describes the chromosome region joining sister chromatids?
Antwort
a centromere
Karte 422
Frage
Which term describes the chromosome-separating microtubule system?
Antwort
the mitotic spindle
Karte 423
Frage
What is the basic sequence of mitosis?
Antwort
Chromosomes condense, align at the cell equator, sister chromatids separate to opposite poles, and new nuclei form.
Karte 424
Frage
Why must DNA replicate before mitosis?
Antwort
Each chromosome must have two copies so each daughter nucleus can receive a complete genome.
Karte 425
Frage
Why are daughter cells from mitosis usually genetically similar?
Antwort
Replicated sister chromatids are separated so each daughter receives one copy of every chromosome.
Karte 426
Frage
What are major roles of mitosis in multicellular organisms?
Antwort
Growth, tissue repair, cell replacement, and some forms of asexual reproduction.
Karte 427
Frage
How do homologous chromosomes differ from sister chromatids?
Antwort
Homologs carry the same gene loci but may have different alleles; sister chromatids are replicated copies of one chromosome.
Karte 428
Frage
What key outcome distinguishes mitosis from meiosis?
Antwort
Mitosis usually preserves chromosome number and similarity; meiosis halves chromosome number and generates genetically varied haploid cells.
Karte 429
Frage
How does cytokinesis commonly occur in animal cells?
Antwort
A contractile ring tightens the plasma membrane into a cleavage furrow.
Karte 430
Frage
How does cytokinesis commonly occur in plant cells?
Antwort
Vesicles fuse at the center to form a cell plate that develops into new membranes and a cell wall.
Karte 431
Frage
What is the purpose of cell-cycle checkpoints?
Antwort
They delay progression when conditions are unsuitable or DNA and chromosome attachment are defective.
Karte 432
Frage
How is loss of cell-cycle control related to cancer?
Antwort
Cells can divide despite damage or growth restraints, producing an expanding abnormal clone.
Karte 433
Frage
What is a gene?
Antwort
A DNA sequence that contributes to a functional product and influences a characteristic or cellular process.
Karte 434
Frage
What is an allele?
Antwort
One of the alternative DNA-sequence forms at a gene locus.
Karte 435
Frage
What is a gene locus?
Antwort
The physical position of a gene on a chromosome.
Karte 436
Frage
What is a genotype?
Antwort
The allele combination of an organism at one or more loci.
Karte 437
Frage
Which term describes a functional DNA sequence?
Antwort
a gene
Karte 438
Frage
Which term describes an alternative form of a gene?
Antwort
an allele
Karte 439
Frage
Which term describes a gene's chromosome position?
Antwort
a gene locus
Karte 440
Frage
Which term describes an organism's allele combination?
Antwort
a genotype
Karte 441
Frage
What is a phenotype?
Antwort
An observable or measurable trait produced by genotype and environment.
Karte 442
Frage
What is homozygous?
Antwort
Having two identical alleles at a diploid locus.
Karte 443
Frage
What is heterozygous?
Antwort
Having two different alleles at a diploid locus.
Karte 444
Frage
What is a dominant allele?
Antwort
An allele expressed in the phenotype of a heterozygote under a specified inheritance model.
Karte 445
Frage
Which term describes an observable trait resulting from genes and environment?
Antwort
a phenotype
Karte 446
Frage
Which term describes having two identical alleles at a locus?
Antwort
homozygous
Karte 447
Frage
Which term describes having two different alleles at a locus?
Antwort
heterozygous
Karte 448
Frage
Which term describes an allele expressed in a heterozygote?
Antwort
a dominant allele
Karte 449
Frage
What is a recessive allele?
Antwort
An allele whose phenotype is masked by a dominant allele in a heterozygote.
Karte 450
Frage
What is a genetic carrier?
Antwort
An unaffected heterozygote who can transmit a recessive disease allele.
Karte 451
Frage
What is a test cross?
Antwort
A cross with a homozygous recessive individual used to infer an unknown dominant phenotype's genotype.
Karte 452
Frage
What is a pedigree?
Antwort
A diagram showing biological relationships and occurrence of a trait across generations.
Karte 453
Frage
Which term describes an allele masked in a heterozygote?
Antwort
a recessive allele
Karte 454
Frage
Which term describes an unaffected heterozygote carrying a recessive disease allele?
Antwort
a genetic carrier
Karte 455
Frage
Which term describes a cross used to reveal an unknown dominant genotype?
Antwort
a test cross
Karte 456
Frage
Which term describes a family diagram tracking a trait across generations?
Antwort
a pedigree
Karte 457
Frage
What does allele segregation mean during gamete formation?
Antwort
The two alleles at a diploid locus separate so each gamete receives one.
Karte 458
Frage
What does a Punnett square predict?
Antwort
Expected genotype and phenotype probabilities from specified parental gametes, not guaranteed family outcomes.
Karte 459
Frage
What phenotypic ratio is expected from Aa × Aa with complete dominance?
Antwort
Approximately 3 dominant phenotype : 1 recessive phenotype.
Karte 460
Frage
What genotypic ratio is expected from Aa × Aa?
Antwort
1 AA : 2 Aa : 1 aa.
Karte 461
Frage
What happens in codominance?
Antwort
Both alleles contribute distinctly to the heterozygous phenotype.
Karte 462
Frage
What happens in incomplete dominance?
Antwort
The heterozygote has a phenotype intermediate between the two homozygotes.
Karte 463
Frage
How can environment affect phenotype without changing genotype?
Antwort
Conditions alter development, physiology, or gene expression, changing the observed trait.
Karte 464
Frage
What is the ultimate source of new alleles?
Antwort
Mutation.
Karte 465
Frage
Why are X-linked recessive traits more common in XY individuals?
Antwort
They have only one X chromosome, so one recessive allele on it can determine the phenotype.
Karte 466
Frage
When is the product rule used in genetic probability?
Antwort
For independent events that must both occur; multiply their probabilities.
Karte 467
Frage
When is the sum rule used in genetic probability?
Antwort
For mutually exclusive alternative outcomes; add their probabilities.
Karte 468
Frage
Why do polygenic traits often show continuous variation?
Antwort
Many loci contribute small effects, creating many possible genotypes and phenotypes, often further influenced by environment.
Karte 469
Frage
What pedigree pattern can suggest an autosomal recessive trait?
Antwort
Unaffected parents can have affected children, and all sexes are affected at similar frequencies.
Karte 470
Frage
What is a species?
Antwort
A group of organisms whose members can potentially interbreed and produce fertile offspring under natural conditions.
Karte 471
Frage
What is binomial nomenclature?
Antwort
The two-part scientific naming system using a genus name followed by a specific epithet.
Karte 472
Frage
What is taxonomy?
Antwort
The naming and classification of organisms.
Karte 473
Frage
What is a biological domain?
Antwort
The broadest commonly used taxonomic rank, separating Bacteria, Archaea, and Eukarya.
Karte 474
Frage
Which term describes a naturally interbreeding group producing fertile offspring?
Antwort
a species
Karte 475
Frage
Which term describes the genus-plus-specific-epithet naming system?
Antwort
binomial nomenclature
Karte 476
Frage
Which term describes the science of naming and classifying organisms?
Antwort
taxonomy
Karte 477
Frage
Which term describes the broadest common taxonomic rank?
Antwort
a biological domain
Karte 478
Frage
What is biodiversity?
Antwort
Variation of life at genetic, species, and ecosystem levels.
Karte 479
Frage
What is an autotroph?
Antwort
An organism that makes organic compounds from inorganic carbon using light or chemical energy.
Karte 480
Frage
What is a heterotroph?
Antwort
An organism that obtains organic carbon by consuming other organisms or their products.
960 Karten
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Karte 481
Frage
What is a unicellular organism?
Antwort
An organism consisting of one cell that carries out all essential life functions.
Karte 482
Frage
Which term describes variation of life across genes, species, and ecosystems?
Antwort
biodiversity
Karte 483
Frage
Which term describes an organism that builds organic matter from inorganic carbon?
Antwort
an autotroph
Karte 484
Frage
Which term describes an organism obtaining organic carbon from other organisms?
Antwort
a heterotroph
Karte 485
Frage
Which term describes an organism made of one cell?
Antwort
a unicellular organism
Karte 486
Frage
What is a multicellular organism?
Antwort
An organism composed of many cooperating cells, often with specialized cell types.
Karte 487
Frage
What is a karyotype?
Antwort
An ordered display of chromosomes used to examine their number and large-scale structure.
Karte 488
Frage
What broad feature distinguishes both Bacteria and Archaea from Eukarya?
Antwort
Their cells lack a nucleus and other membrane-bound organelles.
Karte 489
Frage
What features characterize most plant cells?
Antwort
Cellulose walls, chloroplasts in photosynthetic tissues, and large vacuoles are typical features.
Karte 490
Frage
Which term describes an organism made of many cooperating cells?
Antwort
a multicellular organism
Karte 491
Frage
Which term describes an ordered display of an individual's chromosomes?
Antwort
a karyotype
Karte 492
Frage
How do fungi obtain nutrients?
Antwort
They secrete digestive enzymes and absorb soluble products; their cells usually have chitin-containing walls.
Karte 493
Frage
What distinguishes animal nutrition and cell structure?
Antwort
Animals ingest organic material, and their cells lack cell walls and chloroplasts.
Karte 494
Frage
Why are scientific names useful across languages?
Antwort
A standardized name identifies the same organism internationally and reduces ambiguity from local common names.
Karte 495
Frage
Why can genetic diversity improve a population's resilience?
Antwort
More heritable variation increases the chance that some individuals tolerate new diseases or environmental changes.
Karte 496
Frage
What does ecosystem diversity measure?
Antwort
The variety of habitats, communities, and ecological processes within a region.
Karte 497
Frage
Why are Archaea classified separately from Bacteria?
Antwort
They differ in genetic sequences, membrane chemistry, cell-wall composition, and aspects of molecular machinery.
Karte 498
Frage
Why is the biological species concept difficult to apply to fossils or asexual organisms?
Antwort
Their ability to interbreed and produce fertile offspring cannot be tested in the usual way.
Karte 499
Frage
Does a larger chromosome number necessarily mean a more complex organism?
Antwort
No. Chromosome number varies through fusion, fission, and duplication and does not directly measure biological complexity.
Karte 500
Frage
Does genome size reliably predict organismal complexity?
Antwort
No. Large amounts of noncoding and repeated DNA make genome size a poor simple measure of complexity.
Karte 501
Frage
What evidence can be combined when classifying organisms?
Antwort
Molecular sequences, cell structure, anatomy, development, physiology, and reproductive evidence can all contribute.
Karte 502
Frage
What is gas exchange?
Antwort
Diffusion of respiratory gases between an organism and its environment or transport fluid.
Karte 503
Frage
What is ventilation?
Antwort
Bulk movement of air or water over a gas-exchange surface.
Karte 504
Frage
What is an alveolus?
Antwort
A microscopic air sac in the lung where gases diffuse between air and blood.
Karte 505
Frage
What is pulmonary surfactant?
Antwort
A substance lining alveoli that lowers surface tension and reduces collapse.
Karte 506
Frage
Which term describes diffusion of oxygen and carbon dioxide across a respiratory surface?
Antwort
gas exchange
Karte 507
Frage
Which term describes bulk movement of respiratory medium over an exchange surface?
Antwort
ventilation
Karte 508
Frage
Which term describes a microscopic lung air sac?
Antwort
an alveolus
Karte 509
Frage
Which term describes the alveolar lining that lowers surface tension?
Antwort
pulmonary surfactant
Karte 510
Frage
What is the diaphragm?
Antwort
A sheet of skeletal muscle whose contraction increases thoracic volume during inhalation.
Karte 511
Frage
What is tidal volume?
Antwort
The volume of air moved in or out during a normal breath.
Karte 512
Frage
What is a stoma?
Antwort
A regulated epidermal pore through which gases diffuse in leaves.
Karte 513
Frage
What is countercurrent exchange?
Antwort
Exchange between fluids moving in opposite directions, maintaining a gradient along most of the surface.
Karte 514
Frage
Which term describes the muscle sheet that expands the thorax during inhalation?
Antwort
the diaphragm
Karte 515
Frage
Which term describes air volume moved in one normal breath?
Antwort
tidal volume
Karte 516
Frage
Which term describes a regulated leaf gas-exchange pore?
Antwort
a stoma
Karte 517
Frage
Which term describes opposite fluid flow that maintains an exchange gradient?
Antwort
countercurrent exchange
Karte 518
Frage
What features make an efficient gas-exchange surface?
Antwort
Large area, short diffusion distance, permeability, and maintained concentration gradients.
Karte 519
Frage
How is a steep oxygen gradient maintained across alveoli?
Antwort
Ventilation replenishes alveolar oxygen and blood flow removes absorbed oxygen.
Karte 520
Frage
How does diaphragm contraction cause inhalation?
Antwort
Thoracic volume increases, lung pressure falls below atmospheric pressure, and air flows inward.
Karte 521
Frage
What drives quiet exhalation?
Antwort
The diaphragm relaxes and elastic recoil reduces thoracic and lung volume, raising pressure and pushing air out.
Karte 522
Frage
Why do ventilation rate and depth increase during exercise?
Antwort
They increase oxygen uptake and carbon dioxide removal to support higher cellular respiration.
Karte 523
Frage
How does leaf structure shorten the pathway for carbon dioxide diffusion?
Antwort
Stomata open into air spaces, and mesophyll cells expose moist surfaces close to those spaces.
Karte 524
Frage
Why does carbon dioxide diffuse from tissues into blood?
Antwort
Respiring cells produce carbon dioxide, making its partial pressure higher in tissues than in incoming blood.
Karte 525
Frage
How does countercurrent flow improve oxygen uptake at fish gills?
Antwort
Blood continually meets water with a higher oxygen concentration, preserving diffusion along the lamella.
Karte 526
Frage
Why does closing stomata reduce both water loss and photosynthesis?
Antwort
It limits water-vapor diffusion out but also restricts carbon dioxide diffusion into the leaf.
Karte 527
Frage
What is a circulatory system?
Antwort
A transport system that moves a fluid carrying gases, nutrients, wastes, hormones, and heat through an organism.
Karte 528
Frage
What is an artery?
Antwort
A blood vessel carrying blood away from the heart under relatively high pressure.
Karte 529
Frage
What is a vein?
Antwort
A blood vessel carrying blood toward the heart, usually with low pressure and often valves.
Karte 530
Frage
What is a capillary?
Antwort
A microscopic thin-walled vessel where substances exchange between blood and tissues.
Karte 531
Frage
Which term describes an internal fluid-transport system?
Antwort
a circulatory system
Karte 532
Frage
Which term describes a vessel carrying blood away from the heart?
Antwort
an artery
Karte 533
Frage
Which term describes a vessel carrying blood toward the heart?
Antwort
a vein
Karte 534
Frage
Which term describes a microscopic exchange blood vessel?
Antwort
a capillary
Karte 535
Frage
What is the cardiac cycle?
Antwort
The repeating sequence of heart-chamber contraction and relaxation that pumps blood.
Karte 536
Frage
What is hemoglobin?
Antwort
An iron-containing protein in red blood cells that binds oxygen reversibly.
Karte 537
Frage
What is xylem?
Antwort
Plant vascular tissue that transports water and mineral ions and provides structural support.
Karte 538
Frage
What is phloem?
Antwort
Plant vascular tissue that transports sucrose and other organic solutes between sources and sinks.
Karte 539
Frage
Which term describes the repeating pumping sequence of the heart?
Antwort
the cardiac cycle
Karte 540
Frage
Which term describes the oxygen-carrying protein of red blood cells?
Antwort
hemoglobin
Karte 541
Frage
Which term describes plant tissue carrying water and minerals?
Antwort
xylem
Karte 542
Frage
Which term describes plant tissue carrying organic solutes?
Antwort
phloem
Karte 543
Frage
What is transpiration?
Antwort
Loss of water vapor from plant surfaces, mainly through stomata.
Karte 544
Frage
What is phloem translocation?
Antwort
Movement of organic solutes through phloem from sources to sinks.
Karte 545
Frage
How do a source and a sink differ in plant transport?
Antwort
A source releases assimilates to phloem; a sink removes them for use or storage.
Karte 546
Frage
What makes human circulation a double circulation?
Antwort
Blood passes through the heart once in the pulmonary circuit and again in the systemic circuit during one complete journey.
Karte 547
Frage
Which term describes water-vapor loss from plant surfaces?
Antwort
transpiration
Karte 548
Frage
Which term describes movement of organic solutes through phloem?
Antwort
phloem translocation
Karte 549
Frage
Which term describes the exporting and importing regions of phloem transport?
Antwort
source and sink
Karte 550
Frage
How is an artery adapted to high pressure?
Antwort
It has thick elastic and muscular walls and a relatively narrow lumen.
Karte 551
Frage
How is a vein adapted to return low-pressure blood?
Antwort
It has a wide lumen, thinner walls, and valves that reduce backflow.
Karte 552
Frage
How does capillary structure support exchange?
Antwort
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.
Karte 553
Frage
What determines whether a heart valve opens or closes?
Antwort
Pressure differences across the valve.
Karte 554
Frage
Trace water from soil to the atmosphere through a plant.
Antwort
Soil → root hairs → root tissues → xylem → leaf mesophyll → leaf air spaces → stomata → atmosphere.
Karte 555
Frage
Why may root cells use active transport to absorb mineral ions?
Antwort
Ion concentrations can be lower in soil than in root cells, so uptake must occur against a gradient.
Karte 556
Frage
Why do large multicellular organisms need bulk transport systems?
Antwort
Their low surface-area-to-volume ratio and long diffusion distances make diffusion alone too slow for whole-body supply.
Karte 557
Frage
Why does hemoglobin unload more oxygen in actively respiring tissues?
Antwort
Lower oxygen and often higher carbon dioxide and acidity reduce hemoglobin's oxygen affinity.
Karte 558
Frage
How does transpiration pull water upward through xylem?
Antwort
Evaporation lowers leaf water potential and creates tension; cohesion transmits the pull through the continuous water column.
Karte 559
Frage
How do wind and low humidity generally affect transpiration?
Antwort
Both maintain a steep water-vapor gradient outside the leaf, increasing transpiration if stomata remain open.
Karte 560
Frage
What drives mass flow in phloem?
Antwort
Sugar loading draws in water and raises pressure at a source; unloading lowers pressure at a sink, producing bulk flow.
Karte 561
Frage
Can the same plant organ be a source at one time and a sink at another?
Antwort
Yes. A storage organ may import sugars while filling and export them later during growth or germination.
Karte 562
Frage
What is a neuron?
Antwort
An excitable cell specialized to receive, process, and transmit information.
Karte 563
Frage
What is a sensory neuron?
Antwort
A neuron carrying information from a receptor toward the central nervous system.
Karte 564
Frage
What is a motor neuron?
Antwort
A neuron carrying commands from the central nervous system to an effector.
Karte 565
Frage
What is the resting potential?
Antwort
The voltage difference across an unstimulated neuron's membrane, with the inside negative relative to outside.
Karte 566
Frage
Which term describes an excitable information-transmitting cell?
Antwort
a neuron
Karte 567
Frage
Which term describes a neuron carrying receptor information to the CNS?
Antwort
a sensory neuron
Karte 568
Frage
Which term describes a neuron carrying CNS commands to an effector?
Antwort
a motor neuron
Karte 569
Frage
Which term describes the negative-inside voltage of an unstimulated neuron?
Antwort
the resting potential
Karte 570
Frage
What is an action potential?
Antwort
A brief, self-propagating reversal and restoration of membrane potential along an excitable membrane.
Karte 571
Frage
What is depolarization?
Antwort
A change that makes membrane potential less negative, and during an action potential often positive.
Karte 572
Frage
What is repolarization?
Antwort
Return of membrane potential toward its resting negative value after depolarization.
Karte 573
Frage
What is a synapse?
Antwort
A junction where one cell communicates with another cell.
Karte 574
Frage
Which term describes a brief propagating change in neuron membrane voltage?
Antwort
an action potential
Karte 575
Frage
Which term describes a membrane-voltage change toward a less negative value?
Antwort
depolarization
Karte 576
Frage
Which term describes return toward resting membrane voltage?
Antwort
repolarization
Karte 577
Frage
Which term describes a communication junction between cells?
Antwort
a synapse
Karte 578
Frage
What is a neurotransmitter?
Antwort
A chemical released by a neuron that changes the activity of a target cell.
Karte 579
Frage
What is the refractory period?
Antwort
A brief period after an action potential when another is impossible or requires a stronger stimulus.
Karte 580
Frage
What is myelin?
Antwort
An insulating sheath around some axons that speeds impulse conduction.
Karte 581
Frage
What happens when membrane depolarization reaches threshold?
Antwort
Voltage-gated channels trigger the self-amplifying events of an action potential.
Karte 582
Frage
Which term describes a neuron-released signaling chemical?
Antwort
a neurotransmitter
Karte 583
Frage
Which term describes the recovery interval after an action potential?
Antwort
the refractory period
Karte 584
Frage
Which term describes the insulating axon sheath?
Antwort
myelin
Karte 585
Frage
What does the all-or-none principle mean for an action potential?
Antwort
Once threshold is reached, the action potential has a characteristic size; stronger stimuli increase frequency, not its amplitude.
Karte 586
Frage
How does myelin increase conduction speed?
Antwort
Depolarizing current travels rapidly beneath myelin and action potentials regenerate mainly at gaps in the sheath.
Karte 587
Frage
What is the basic sequence at a chemical synapse?
Antwort
An impulse triggers neurotransmitter release; it diffuses across the cleft, binds receptors, and alters the postsynaptic cell.
Karte 588
Frage
Why can a reflex response be rapid?
Antwort
A short neural pathway produces an automatic response without waiting for conscious processing.
Karte 589
Frage
What is sensory transduction?
Antwort
Conversion of a physical or chemical stimulus into an electrical signal in a receptor cell.
Karte 590
Frage
How does an action potential propagate along an axon?
Antwort
Local current depolarizes the next membrane region to threshold, opening voltage-gated channels there.
Karte 591
Frage
Why does an action potential normally travel in one direction along an axon?
Antwort
The membrane just behind it is refractory and cannot immediately fire again.
Karte 592
Frage
How is neurotransmitter action ended?
Antwort
The transmitter is removed by enzymatic breakdown, reuptake, or diffusion away.
Karte 593
Frage
What is sensory adaptation?
Antwort
Reduced receptor or neural response during a constant, unchanging stimulus.
Karte 594
Frage
How can a drug alter synaptic transmission?
Antwort
It may mimic or block a transmitter, change its release, or change its removal from the synaptic cleft.
Karte 595
Frage
What is an organ system?
Antwort
A group of organs coordinating to perform major functions for an organism.
Karte 596
Frage
What is a hormone?
Antwort
A signaling molecule released into transport fluid and acting on target cells with suitable receptors.
Karte 597
Frage
What is an endocrine gland?
Antwort
A gland that secretes hormones into extracellular fluid and blood rather than through a duct.
Karte 598
Frage
What is a hormone target cell?
Antwort
A cell able to respond because it has the appropriate receptor.
Karte 599
Frage
Which term describes a coordinated group of organs?
Antwort
an organ system
Karte 600
Frage
Which term describes a long-distance chemical messenger carried in body fluid?
Antwort
a hormone
Karte 601
Frage
Which term describes a ductless hormone-secreting gland?
Antwort
an endocrine gland
Karte 602
Frage
Which term describes a cell with a receptor for a particular hormone?
Antwort
a hormone target cell
Karte 603
Frage
What is digestion?
Antwort
Mechanical and chemical breakdown of food into molecules small enough to absorb.
Karte 604
Frage
What is absorption?
Antwort
Movement of digested nutrients across an exchange surface into blood or lymph.
Karte 605
Frage
What is peristalsis?
Antwort
Coordinated waves of smooth-muscle contraction that move material through the digestive tract.
Karte 606
Frage
What is an intestinal villus?
Antwort
A finger-like projection increasing the absorptive surface of the small intestine.
Karte 607
Frage
Which term describes breakdown of food into absorbable molecules?
Antwort
digestion
Karte 608
Frage
Which term describes movement of digested nutrients into transport fluids?
Antwort
absorption
Karte 609
Frage
Which term describes wave-like gut contractions moving contents?
Antwort
peristalsis
Karte 610
Frage
Which term describes a finger-like intestinal absorption projection?
Antwort
an intestinal villus
Karte 611
Frage
What is excretion?
Antwort
Removal of metabolic waste products from the body.
Karte 612
Frage
What is a nephron?
Antwort
The microscopic functional unit of the kidney that filters blood and modifies filtrate into urine.
Karte 613
Frage
What is ultrafiltration?
Antwort
Pressure-driven filtration of small molecules from blood into a kidney capsule while cells and most proteins remain in blood.
Karte 614
Frage
What is selective reabsorption?
Antwort
Recovery of useful substances and regulated amounts of water and ions from kidney filtrate into blood.
Karte 615
Frage
Which term describes removal of metabolic wastes?
Antwort
excretion
Karte 616
Frage
Which term describes the kidney's microscopic functional unit?
Antwort
a nephron
Karte 617
Frage
Which term describes pressure filtration at the start of a nephron?
Antwort
ultrafiltration
Karte 618
Frage
Which term describes return of useful substances from kidney filtrate to blood?
Antwort
selective reabsorption
Karte 619
Frage
What is skeletal muscle?
Antwort
Striated voluntary muscle attached to the skeleton and used for movement and posture.
Karte 620
Frage
What is an antagonistic muscle pair?
Antwort
Two muscles producing opposite movements at a joint because muscles pull but do not push.
Karte 621
Frage
How do nervous and endocrine signaling generally differ?
Antwort
Neural signals are rapid and targeted; hormonal signals are usually slower, longer-lasting, and distributed through body fluids.
Karte 622
Frage
Why does a circulating hormone affect only some cells?
Antwort
Only target cells express receptors that recognize the hormone and activate a response.
Karte 623
Frage
Which term describes voluntary striated muscle that moves the skeleton?
Antwort
skeletal muscle
Karte 624
Frage
Which term describes two muscles producing opposite joint movements?
Antwort
an antagonistic muscle pair
Karte 625
Frage
What is the final absorbable product of most dietary carbohydrate digestion?
Antwort
Monosaccharides, especially glucose.
Karte 626
Frage
What are the main absorbable products of protein digestion?
Antwort
Amino acids and small peptides that are completed to amino acids during absorption.
Karte 627
Frage
How is the small intestine adapted for absorption?
Antwort
Folds, villi, and microvilli increase area; a thin epithelium, rich blood supply, and lymph vessels support transport.
Karte 628
Frage
Name three integrative roles of the liver.
Antwort
It processes absorbed nutrients, regulates blood chemistry, detoxifies substances, produces bile, and converts ammonia to urea; any three are sufficient.
Karte 629
Frage
Why are blood cells and most plasma proteins absent from normal kidney filtrate?
Antwort
They are too large to cross the filtration barrier.
Karte 630
Frage
How do muscles move a bone at a joint?
Antwort
Contraction shortens the muscle, pulling through a tendon on the bone.
Karte 631
Frage
Why are antagonistic muscles needed at many joints?
Antwort
A muscle can pull in one direction but cannot push itself back, so an opposing muscle produces the reverse movement.
Karte 632
Frage
Why must organ systems be integrated rather than acting independently?
Antwort
Each system depends on materials, signals, waste removal, and stable conditions supplied by other systems.
Karte 633
Frage
Why do many absorbed lipids enter lymph before blood?
Antwort
Intestinal cells package them into lipoprotein particles too large to enter ordinary blood capillaries directly.
Karte 634
Frage
Why is glucose normally absent from final urine?
Antwort
Filtered glucose is selectively reabsorbed into blood when transporter capacity is not exceeded.
Karte 635
Frage
How do respiratory, circulatory, and muscular systems cooperate during exercise?
Antwort
Ventilation supplies oxygen, circulation transports gases and fuels, and muscles use ATP while returning carbon dioxide, heat, and metabolites.
Karte 636
Frage
How do liver, circulation, and kidneys cooperate in nitrogen-waste removal?
Antwort
The liver converts toxic ammonia to urea, blood carries urea, and kidneys filter and excrete it.
Karte 637
Frage
What is a pathogen?
Antwort
A biological agent capable of causing disease.
Karte 638
Frage
What is an antigen?
Antwort
A molecule recognized specifically by an antibody or lymphocyte receptor.
Karte 639
Frage
What is innate immunity?
Antwort
Rapid, nonspecific defense mechanisms present without prior exposure.
Karte 640
Frage
What is adaptive immunity?
Antwort
Specific defense that develops through lymphocyte activation and can form memory.
Karte 641
Frage
Which term describes a disease-causing biological agent?
Antwort
a pathogen
Karte 642
Frage
Which term describes a molecule specifically recognized by adaptive immune receptors?
Antwort
an antigen
Karte 643
Frage
Which term describes rapid nonspecific immune defense?
Antwort
innate immunity
Karte 644
Frage
Which term describes specific immune defense capable of memory?
Antwort
adaptive immunity
Karte 645
Frage
What is a phagocyte?
Antwort
A cell that engulfs and digests microbes, particles, or damaged cells.
Karte 646
Frage
What is a lymphocyte?
Antwort
An adaptive immune cell with receptors specific to particular antigens.
Karte 647
Frage
What is an antibody?
Antwort
A secreted immunoglobulin that binds a specific antigen.
Karte 648
Frage
What is a B lymphocyte?
Antwort
A lymphocyte that can differentiate into antibody-secreting plasma cells and memory cells.
Karte 649
Frage
Which term describes an engulfing immune cell?
Antwort
a phagocyte
Karte 650
Frage
Which term describes an antigen-specific adaptive immune cell?
Antwort
a lymphocyte
Karte 651
Frage
Which term describes a secreted antigen-binding immunoglobulin?
Antwort
an antibody
Karte 652
Frage
Which term describes the lymphocyte lineage that produces antibody-secreting cells?
Antwort
a B lymphocyte
Karte 653
Frage
What is a helper T cell?
Antwort
A lymphocyte that coordinates immune responses through contact signals and cytokines.
Karte 654
Frage
What is an immune memory cell?
Antwort
A long-lived lymphocyte that responds rapidly after re-exposure to its antigen.
Karte 655
Frage
What is vaccination?
Antwort
Deliberate exposure to a safe form or component of an antigen to generate protective immune memory.
Karte 656
Frage
What is an antibiotic?
Antwort
A substance that kills bacteria or inhibits their growth at clinically useful doses.
Karte 657
Frage
Which term describes the T cell that coordinates other immune cells?
Antwort
a helper T cell
Karte 658
Frage
Which term describes a long-lived lymphocyte enabling faster re-exposure response?
Antwort
an immune memory cell
Karte 659
Frage
Which term describes safe antigen exposure used to create immune memory?
Antwort
vaccination
Karte 660
Frage
Which term describes a drug acting against bacteria?
Antwort
an antibiotic
Karte 661
Frage
What are examples of first-line defenses against pathogens?
Antwort
Intact skin, mucus, cilia, antimicrobial secretions, stomach acidity, and competing microbiota.
Karte 662
Frage
How does inflammation help defend damaged tissue?
Antwort
It increases local blood flow and vessel permeability and recruits immune cells and defensive molecules.
Karte 663
Frage
What happens during phagocytosis?
Antwort
A cell surrounds a particle in a vesicle, then fuses it with digestive compartments to destroy or process it.
Karte 664
Frage
How can antibodies help eliminate a pathogen?
Antwort
They can neutralize targets, block attachment, clump particles, and mark them for phagocytosis or complement attack.
Karte 665
Frage
Why can a vaccine generate protection without causing the full disease?
Antwort
It presents antigen in a weakened, inactivated, partial, or encoded form that stimulates immunity with much lower risk.
Karte 666
Frage
Why do antibiotics not treat viral infections?
Antwort
Viruses lack the bacterial structures and independent metabolic processes targeted by antibiotics.
Karte 667
Frage
What determines the antigen specificity of a lymphocyte?
Antwort
The molecular shape and chemistry of its unique surface receptor.
Karte 668
Frage
What is clonal selection?
Antwort
An antigen activates lymphocytes with matching receptors, causing them to proliferate and differentiate.
Karte 669
Frage
Why is a secondary adaptive immune response usually faster and stronger?
Antwort
Memory cells are more numerous and activate rapidly, producing effective cells and antibodies sooner.
Karte 670
Frage
How can high vaccination coverage protect some unvaccinated people?
Antwort
Reduced transmission makes encounters with infectious individuals less likely, though protection is incomplete and pathogen-dependent.
Karte 671
Frage
How does antibiotic use select for resistant bacteria?
Antwort
Susceptible bacteria are removed while resistant variants survive and reproduce, increasing resistance-allele frequency.
Karte 672
Frage
Why can unnecessary or incomplete antibiotic exposure promote resistance?
Antwort
It creates selection favoring resistant cells while potentially leaving surviving bacteria to multiply and spread.
Karte 673
Frage
What is an allergy?
Antwort
An immune response to a normally harmless antigen that causes tissue symptoms or damage.
Karte 674
Frage
What is asexual reproduction?
Antwort
Production of offspring from one parent without fusion of gametes.
Karte 675
Frage
What is sexual reproduction?
Antwort
Production of offspring involving fusion of haploid gametes.
Karte 676
Frage
What is a gamete?
Antwort
A haploid reproductive cell able to fuse with another gamete.
Karte 677
Frage
What is fertilization?
Antwort
Fusion of gamete nuclei to form a diploid zygote.
Karte 678
Frage
Which term describes reproduction without gamete fusion?
Antwort
asexual reproduction
Karte 679
Frage
Which term describes reproduction involving gamete fusion?
Antwort
sexual reproduction
Karte 680
Frage
Which term describes a haploid reproductive cell?
Antwort
a gamete
Karte 681
Frage
Which term describes fusion of gamete nuclei?
Antwort
fertilization
Karte 682
Frage
What is a zygote?
Antwort
The diploid cell formed by fertilization.
Karte 683
Frage
What is meiosis?
Antwort
Cell division that halves chromosome number and usually produces genetically varied haploid cells.
Karte 684
Frage
What is ovulation?
Antwort
Release of a secondary oocyte from an ovary.
Karte 685
Frage
What is implantation?
Antwort
Attachment and embedding of an early embryo in the uterine lining.
Karte 686
Frage
Which term describes the first diploid cell after fertilization?
Antwort
a zygote
Karte 687
Frage
Which term describes division producing varied haploid cells?
Antwort
meiosis
Karte 688
Frage
Which term describes release of an oocyte from an ovary?
Antwort
ovulation
Karte 689
Frage
Which term describes embedding of an early embryo in the uterine lining?
Antwort
implantation
Karte 690
Frage
What is the placenta?
Antwort
A temporary organ that exchanges materials between maternal and fetal blood supplies without normally mixing them directly.
Karte 691
Frage
What is pollination?
Antwort
Transfer of pollen from an anther to a receptive stigma.
Karte 692
Frage
Why does sexual reproduction usually produce more genetic variation than asexual reproduction?
Antwort
Meiosis reshuffles alleles and random fertilization combines genomes from two gametes.
Karte 693
Frage
Why must gametes be haploid?
Antwort
Fusion of two haploid gametes restores the diploid chromosome number instead of doubling it each generation.
Karte 694
Frage
Which term describes the maternal-fetal exchange organ?
Antwort
the placenta
Karte 695
Frage
Which term describes transfer of pollen to a stigma?
Antwort
pollination
Karte 696
Frage
What are major roles of FSH in the ovarian cycle?
Antwort
It stimulates follicle development and supports estrogen secretion.
Karte 697
Frage
What is a major role of the mid-cycle LH surge?
Antwort
It triggers ovulation and formation of the corpus luteum.
Karte 698
Frage
How does estrogen contribute to the uterine cycle?
Antwort
It promotes repair and thickening of the uterine lining after menstruation.
Karte 699
Frage
How does progesterone contribute to the uterine cycle?
Antwort
It maintains a thick, secretory uterine lining after ovulation.
Karte 700
Frage
Where does human fertilization usually occur?
Antwort
In an oviduct, before the early embryo reaches the uterus.
Karte 701
Frage
What happens after compatible pollen reaches a flower's stigma?
Antwort
A pollen tube grows toward an ovule and delivers male nuclei for fertilization.
Karte 702
Frage
Why does menstruation usually begin if pregnancy does not occur?
Antwort
The corpus luteum degenerates, progesterone and estrogen fall, and the uterine lining is no longer maintained.
Karte 703
Frage
What substances commonly cross the placenta between mother and fetus?
Antwort
Oxygen and nutrients move toward the fetus; carbon dioxide and nitrogenous wastes move toward the mother.
Karte 704
Frage
How can contraception prevent pregnancy in different ways?
Antwort
Methods can inhibit ovulation, block sperm from reaching an egg, prevent fertilization, or permanently interrupt the reproductive ducts.
Karte 705
Frage
What is homeostasis?
Antwort
Maintenance of internal conditions within ranges compatible with normal function despite change.
Karte 706
Frage
What is negative feedback?
Antwort
Control in which a deviation triggers responses that oppose the original change.
Karte 707
Frage
What is a set point?
Antwort
The target value or range around which a regulated variable is maintained.
Karte 708
Frage
What is a homeostatic receptor?
Antwort
A sensor that detects a change in a regulated variable.
Karte 709
Frage
Which term describes maintenance of a stable functional internal environment?
Antwort
homeostasis
Karte 710
Frage
Which term describes feedback that counteracts a deviation?
Antwort
negative feedback
Karte 711
Frage
Which term describes the target around which a variable is regulated?
Antwort
a set point
Karte 712
Frage
Which term describes the sensor in a feedback system?
Antwort
a homeostatic receptor
Karte 713
Frage
What is a control center?
Antwort
The component that compares information with a target and coordinates a response.
Karte 714
Frage
What is an effector?
Antwort
A muscle, gland, or other component that carries out a control response.
Karte 715
Frage
What is thermoregulation?
Antwort
Control of body temperature within a functional range.
Karte 716
Frage
What is vasodilation?
Antwort
Widening of blood vessels, often increasing blood flow near the skin.
Karte 717
Frage
Which term describes the feedback component that evaluates input and directs a response?
Antwort
a control center
Karte 718
Frage
Which term describes the component that executes a physiological response?
Antwort
an effector
Karte 719
Frage
Which term describes physiological regulation of body temperature?
Antwort
thermoregulation
Karte 720
Frage
Which term describes widening of blood vessels?
Antwort
vasodilation
Karte 721
Frage
What is vasoconstriction?
Antwort
Narrowing of blood vessels, often reducing blood flow near the skin.
Karte 722
Frage
What is insulin?
Antwort
A pancreatic hormone that lowers elevated blood glucose by promoting uptake and storage.
Karte 723
Frage
What is glucagon?
Antwort
A pancreatic hormone that raises low blood glucose by promoting release of stored fuel.
Karte 724
Frage
What are the main components of a homeostatic feedback loop?
Antwort
A regulated variable, receptor, control center, effectors, and responses that alter the variable.
Karte 725
Frage
Which term describes narrowing of blood vessels?
Antwort
vasoconstriction
Karte 726
Frage
Which term describes the pancreatic hormone that lowers blood glucose?
Antwort
insulin
Karte 727
Frage
Which term describes the pancreatic hormone that raises blood glucose?
Antwort
glucagon
Karte 728
Frage
What happens when blood glucose rises after a meal?
Antwort
Insulin secretion increases, promoting glucose uptake and storage so blood glucose falls toward its normal range.
Karte 729
Frage
What happens when blood glucose falls during fasting?
Antwort
Glucagon secretion increases, promoting glycogen breakdown and glucose release by the liver.
Karte 730
Frage
How does sweating cool the body?
Antwort
Evaporation of water from skin transfers heat to the environment.
Karte 731
Frage
How does skin vasodilation increase heat loss?
Antwort
It brings more warm blood near the surface, increasing transfer of heat to the environment.
Karte 732
Frage
How does shivering warm the body?
Antwort
Rapid involuntary muscle contractions increase respiration and heat production.
Karte 733
Frage
Does homeostasis keep internal conditions perfectly constant?
Antwort
No. Variables fluctuate within controlled ranges around target values.
Karte 734
Frage
How does ADH help conserve water?
Antwort
It increases water permeability in kidney collecting ducts, so more water is reabsorbed and urine becomes more concentrated.
Karte 735
Frage
How should ADH secretion change during dehydration?
Antwort
It should increase, promoting greater water reabsorption by the kidneys.
Karte 736
Frage
How does positive feedback differ from negative feedback?
Antwort
Positive feedback amplifies a change until an endpoint; negative feedback opposes a change and stabilizes a variable.
Karte 737
Frage
Why can diabetes mellitus cause persistently high blood glucose?
Antwort
Insulin production may be insufficient or target cells may respond poorly to insulin.
Karte 738
Frage
What is biological evolution?
Antwort
Change in heritable characteristics or allele frequencies of a population across generations.
Karte 739
Frage
What is allele frequency?
Antwort
The proportion of gene copies in a population represented by a particular allele.
Karte 740
Frage
What is microevolution?
Antwort
Evolutionary change in allele frequencies within populations over relatively short timescales.
Karte 741
Frage
What is speciation?
Antwort
Evolutionary formation of new species.
Karte 742
Frage
Which term describes change in a population's heritable composition across generations?
Antwort
biological evolution
Karte 743
Frage
Which term describes the proportion of a population's gene copies that are one allele?
Antwort
allele frequency
Karte 744
Frage
Which term describes short-timescale allele-frequency change within populations?
Antwort
microevolution
Karte 745
Frage
Which term describes formation of new species?
Antwort
speciation
Karte 746
Frage
What is reproductive isolation?
Antwort
Barriers that prevent or greatly reduce gene flow between populations.
Karte 747
Frage
What is allopatric speciation?
Antwort
Speciation after populations become geographically separated and diverge.
Karte 748
Frage
What is sympatric speciation?
Antwort
Speciation without geographic separation, through reproductive isolation within the same area.
Karte 749
Frage
What are homologous structures?
Antwort
Structures similar because they were inherited from a common ancestor, even if their functions differ.
Karte 750
Frage
Which term describes barriers reducing gene flow between populations?
Antwort
reproductive isolation
Karte 751
Frage
Which term describes speciation following geographic separation?
Antwort
allopatric speciation
Karte 752
Frage
Which term describes speciation within the same geographic area?
Antwort
sympatric speciation
Karte 753
Frage
Which term describes structures similar through common ancestry?
Antwort
homologous structures
Karte 754
Frage
What are analogous structures?
Antwort
Structures with similar functions that evolved independently rather than from the same ancestral structure.
Karte 755
Frage
What is a common ancestor?
Antwort
An ancestral population from which two or more descendant lineages evolved.
Karte 756
Frage
How does the fossil record provide evidence for evolution?
Antwort
It documents organisms from different times, including appearance, change, persistence, and extinction of lineages.
Karte 757
Frage
How do DNA and protein sequences provide evidence of common ancestry?
Antwort
Shared sequences are inherited; greater similarity generally indicates more recent common ancestry.
Karte 758
Frage
Which term describes functionally similar structures of independent evolutionary origin?
Antwort
analogous structures
Karte 759
Frage
Which term describes an ancestral population shared by descendant lineages?
Antwort
a common ancestor
Karte 760
Frage
What is the evolutionary significance of extinction?
Antwort
It permanently ends a lineage and can alter ecological opportunities and the future diversification of survivors.
Karte 761
Frage
Do individual organisms evolve during their lifetimes?
Antwort
No. Individuals develop and acclimate; evolution is heritable change in populations across generations.
Karte 762
Frage
Why is evolution represented as a branching tree rather than a ladder?
Antwort
Lineages split from common ancestors; living species are not arranged as stages toward a single goal.
Karte 763
Frage
How can island species support evolutionary explanations?
Antwort
Their similarities to nearby mainland ancestors and unique local adaptations fit divergence after colonization and isolation.
Karte 764
Frage
How can geographic isolation lead to reproductive isolation?
Antwort
Separated populations accumulate different mutations and experience different selection and drift until interbreeding is reduced.
Karte 765
Frage
Why can continuing gene flow slow speciation?
Antwort
Movement of alleles between populations counteracts genetic divergence.
Karte 766
Frage
Why can unrelated species evolve similar traits?
Antwort
Similar environmental challenges can favor similar functional solutions through convergent evolution.
Karte 767
Frage
Which parts of evolution are random and which are nonrandom?
Antwort
Mutation and many sampling effects are random with respect to need; natural selection nonrandomly favors variants that reproduce better in a given environment.
Karte 768
Frage
What is conservation biology?
Antwort
The science and practice of protecting biodiversity, ecological processes, and evolutionary potential.
Karte 769
Frage
What is habitat fragmentation?
Antwort
Division of continuous habitat into smaller, isolated patches.
Karte 770
Frage
What is an endangered species?
Antwort
A species facing a high risk of extinction in the wild.
Karte 771
Frage
What is in situ conservation?
Antwort
Protection of species in their natural habitats and ecological communities.
Karte 772
Frage
Which term describes the protection of biodiversity and ecological processes?
Antwort
conservation biology
Karte 773
Frage
Which term describes division of habitat into isolated patches?
Antwort
habitat fragmentation
Karte 774
Frage
Which term describes a species at high risk of extinction?
Antwort
an endangered species
Karte 775
Frage
Which term describes conservation within natural habitat?
Antwort
in situ conservation
Karte 776
Frage
What is ex situ conservation?
Antwort
Protection of organisms or genetic material outside the natural habitat.
Karte 777
Frage
What is a population bottleneck?
Antwort
A sharp population reduction that can remove genetic variation by chance.
Karte 778
Frage
What is a wildlife corridor?
Antwort
Habitat connecting isolated patches to permit movement and gene flow.
Karte 779
Frage
What major human-driven processes threaten biodiversity?
Antwort
Habitat loss, overexploitation, invasive species, pollution, and climate change.
Karte 780
Frage
Which term describes conservation outside natural habitat?
Antwort
ex situ conservation
Karte 781
Frage
Which term describes a severe population reduction that loses genetic diversity?
Antwort
a population bottleneck
Karte 782
Frage
Which term describes habitat linking isolated populations?
Antwort
a wildlife corridor
Karte 783
Frage
What makes a protected area more effective than a boundary alone?
Antwort
Adequate size, representative habitat, enforcement, connectivity, local support, and management of external threats.
Karte 784
Frage
Why is long-term population monitoring important in conservation?
Antwort
It reveals trends, tests whether management works, and provides early warning of decline.
Karte 785
Frage
How can ecosystem services support the case for conservation?
Antwort
Healthy ecosystems provide benefits such as pollination, water purification, carbon storage, soil formation, and cultural value.
Karte 786
Frage
Why are very small populations especially vulnerable to extinction?
Antwort
Chance events, inbreeding, low genetic diversity, and difficulty finding mates can reinforce decline.
Karte 787
Frage
What are benefits and limits of captive-breeding programs?
Antwort
They can prevent immediate extinction and manage breeding, but may lose diversity, alter behavior, and fail without safe habitat for release.
Karte 788
Frage
Why can controlling an invasive species aid conservation?
Antwort
It can reduce predation, competition, disease, or habitat alteration affecting native species.
Karte 789
Frage
Why must conservation priorities consider more than species count?
Antwort
Endemism, evolutionary distinctness, ecological roles, threat severity, feasibility, and human needs also matter.
Karte 790
Frage
What is an adaptation?
Antwort
A heritable characteristic that increases reproductive success in a particular environment.
Karte 791
Frage
What is acclimation?
Antwort
A reversible physiological or behavioral adjustment by an individual to environmental change.
Karte 792
Frage
What is a structural adaptation?
Antwort
An inherited anatomical feature that improves performance in an environment.
Karte 793
Frage
What is a physiological adaptation?
Antwort
An inherited functional or biochemical feature that improves performance in an environment.
Karte 794
Frage
Which term describes a heritable trait improving reproductive success in context?
Antwort
an adaptation
Karte 795
Frage
Which term describes an individual's reversible adjustment to environmental change?
Antwort
acclimation
Karte 796
Frage
Which term describes an adaptive anatomical feature?
Antwort
a structural adaptation
Karte 797
Frage
Which term describes an adaptive functional or biochemical feature?
Antwort
a physiological adaptation
Karte 798
Frage
What is a behavioral adaptation?
Antwort
An inherited behavior pattern that improves survival or reproduction.
Karte 799
Frage
What is an environmental tolerance range?
Antwort
The range of an abiotic condition within which an organism can survive and reproduce.
Karte 800
Frage
What is evolutionary fitness?
Antwort
Relative contribution of an individual or genotype to future generations.
Karte 801
Frage
How can a thick cuticle and reduced leaves help a desert plant?
Antwort
The cuticle lowers surface permeability, while smaller leaves reduce the area from which water can evaporate.
Karte 802
Frage
Which term describes an adaptive behavior pattern?
Antwort
a behavioral adaptation
Karte 803
Frage
Which term describes the survivable range of an abiotic condition?
Antwort
an environmental tolerance range
Karte 804
Frage
Which term describes relative reproductive contribution to future generations?
Antwort
evolutionary fitness
Karte 805
Frage
How can a streamlined body adapt an aquatic animal to movement?
Antwort
It reduces drag, lowering the energy needed to move through water.
Karte 806
Frage
Does an organism develop an adaptation because it needs one?
Antwort
No. Heritable variants arise without regard to need, and selection changes their frequencies across generations.
Karte 807
Frage
Why may organisms from different thermal environments have enzymes with different temperature optima?
Antwort
Selection favors protein structures that balance flexibility and stability under local temperatures.
Karte 808
Frage
Why is an adaptation rarely beneficial in every environment?
Antwort
Traits carry costs and their advantage depends on local resources, competitors, predators, and physical conditions.
Karte 809
Frage
How does phenotypic plasticity differ from genetic adaptation?
Antwort
Plasticity lets one genotype produce different phenotypes; adaptation is a heritable population trait shaped across generations.
Karte 810
Frage
What is local adaptation?
Antwort
A population has higher fitness in its home environment than foreign populations because selection favored local traits.
Karte 811
Frage
What is an ecological niche?
Antwort
The set of environmental conditions, resources, interactions, and functional roles associated with a species.
Karte 812
Frage
What is a habitat?
Antwort
The physical place or environment where an organism lives.
Karte 813
Frage
What is a fundamental niche?
Antwort
The full range of conditions and resources a species could use without limiting biotic interactions.
Karte 814
Frage
What is a realized niche?
Antwort
The conditions and resources a species actually uses after competition and other interactions.
Karte 815
Frage
Which term describes a species' environmental requirements and ecological role?
Antwort
an ecological niche
Karte 816
Frage
Which term describes the place where an organism lives?
Antwort
a habitat
Karte 817
Frage
Which term describes the potential niche without limiting biotic interactions?
Antwort
a fundamental niche
Karte 818
Frage
Which term describes the niche actually occupied in nature?
Antwort
a realized niche
Karte 819
Frage
What is competition?
Antwort
An interaction in which organisms reduce one another's access to a limited resource.
Karte 820
Frage
What is mutualism?
Antwort
An interaction in which both participating species benefit.
Karte 821
Frage
What is predation?
Antwort
An interaction in which one organism kills and consumes another.
Karte 822
Frage
How does a habitat differ from a niche?
Antwort
A habitat is where an organism lives; a niche includes how it uses conditions and resources and interacts there.
Karte 823
Frage
Which term describes an interaction over a limited resource that harms both competitors?
Antwort
competition
Karte 824
Frage
Which term describes an interspecific interaction benefiting both partners?
Antwort
mutualism
Karte 825
Frage
Which term describes an interaction where one organism kills and eats another?
Antwort
predation
Karte 826
Frage
What kinds of factors define a niche?
Antwort
Abiotic factors such as temperature and moisture, plus biotic factors such as food, competitors, predators, and partners.
Karte 827
Frage
What does competitive exclusion predict?
Antwort
Species with effectively identical niches cannot coexist indefinitely under stable conditions; one is excluded or niches diverge.
Karte 828
Frage
How can resource partitioning reduce competition?
Antwort
Species use different resources, places, or times, reducing niche overlap.
Karte 829
Frage
What is a keystone species?
Antwort
A species whose effect on community structure is disproportionately large relative to its abundance.
Karte 830
Frage
Why can an introduced species expand rapidly in a new community?
Antwort
It may encounter abundant resources, suitable climate, and fewer predators, pathogens, or competitors.
Karte 831
Frage
Can an organism alter the niche conditions of other species?
Antwort
Yes. Ecosystem engineers modify habitat structure or resource availability, changing opportunities for other organisms.
Karte 832
Frage
What is a population?
Antwort
Individuals of the same species living in the same area at the same time.
Karte 833
Frage
What is an ecological community?
Antwort
Populations of different species living and interacting in an area.
Karte 834
Frage
What is an ecosystem?
Antwort
A community together with its physical environment and their interactions.
Karte 835
Frage
What is carrying capacity?
Antwort
The population size an environment can sustain over time under given conditions.
Karte 836
Frage
Which term describes same-species individuals sharing an area and time?
Antwort
a population
Karte 837
Frage
Which term describes interacting populations of different species?
Antwort
an ecological community
Karte 838
Frage
Which term describes a community plus its abiotic environment?
Antwort
an ecosystem
Karte 839
Frage
Which term describes the long-term supportable population size?
Antwort
carrying capacity
Karte 840
Frage
What is population density?
Antwort
The number of individuals per unit area or volume.
Karte 841
Frage
What is a limiting factor?
Antwort
A resource or condition that restricts population growth or distribution.
Karte 842
Frage
What is a density-dependent factor?
Antwort
A factor whose effect strengthens as population density increases.
Karte 843
Frage
What is a density-independent factor?
Antwort
A factor whose effect is not primarily determined by population density.
Karte 844
Frage
Which term describes individuals per unit area or volume?
Antwort
population density
Karte 845
Frage
Which term describes a resource or condition restricting a population?
Antwort
a limiting factor
Karte 846
Frage
Which term describes a factor with stronger effects at higher density?
Antwort
a density-dependent factor
Karte 847
Frage
Which term describes a factor acting largely regardless of population density?
Antwort
a density-independent factor
Karte 848
Frage
What is exponential population growth?
Antwort
Growth at a constant per-capita rate, producing a J-shaped curve under ideal conditions.
Karte 849
Frage
What is logistic population growth?
Antwort
Growth that slows as population size approaches carrying capacity, producing an S-shaped model.
Karte 850
Frage
What four processes directly change population size?
Antwort
Births and immigration increase it; deaths and emigration decrease it.
Karte 851
Frage
Under what conditions can exponential growth occur temporarily?
Antwort
Resources are abundant and limiting effects such as competition, disease, and predation are weak.
Karte 852
Frage
Which term describes J-shaped growth at constant per-capita rate?
Antwort
exponential population growth
Karte 853
Frage
Which term describes S-shaped growth that slows near carrying capacity?
Antwort
logistic population growth
Karte 854
Frage
Why is infectious disease often density dependent?
Antwort
Close or frequent contact at high density increases transmission opportunities.
Karte 855
Frage
Give an example of a density-independent population factor.
Antwort
A severe storm, wildfire, drought, or freeze can affect populations regardless of their initial density.
Karte 856
Frage
When is quadrat sampling useful?
Antwort
For estimating abundance or frequency of sessile or slow-moving organisms in defined areas.
Karte 857
Frage
What can a transect reveal?
Antwort
How species occurrence or abundance changes along an environmental gradient.
Karte 858
Frage
What can happen when a population overshoots carrying capacity?
Antwort
Resource depletion may raise mortality or lower reproduction, causing decline or oscillation.
Karte 859
Frage
What is the basic mark–recapture estimate of population size?
Antwort
First sample marked × second sample total ÷ marked individuals recaptured.
Karte 860
Frage
What assumptions improve a mark–recapture estimate?
Antwort
Marks persist and do not affect survival, marked individuals mix, capture probability is similar, and the population is effectively closed.
Karte 861
Frage
Why does a correlation between two population variables not prove causation?
Antwort
A third factor, reverse influence, chance, or biased sampling could produce the association.
Karte 862
Frage
What is a trophic level?
Antwort
A feeding position in a food chain or web.
Karte 863
Frage
What is a producer?
Antwort
An autotroph that converts inorganic carbon into organic matter.
Karte 864
Frage
What is a consumer?
Antwort
An organism obtaining energy and matter by eating other organisms or organic material.
Karte 865
Frage
What is a decomposer?
Antwort
An organism that externally digests dead material and wastes and absorbs the products.
Karte 866
Frage
Which term describes a feeding position in an ecosystem?
Antwort
a trophic level
Karte 867
Frage
Which term describes an autotroph forming organic matter?
Antwort
a producer
Karte 868
Frage
Which term describes an organism feeding on other organic matter?
Antwort
a consumer
Karte 869
Frage
Which term describes an organism digesting dead organic matter externally?
Antwort
a decomposer
Karte 870
Frage
What is a food chain?
Antwort
A linear representation of feeding and energy-transfer relationships.
Karte 871
Frage
What is a food web?
Antwort
A network of interconnected feeding relationships in a community.
Karte 872
Frage
What is gross primary productivity?
Antwort
The total rate at which producers capture energy into organic matter.
Karte 873
Frage
What is net primary productivity?
Antwort
Producer energy stored as new biomass after subtracting producer respiration from gross primary productivity.
Karte 874
Frage
Which term describes a linear feeding sequence?
Antwort
a food chain
Karte 875
Frage
Which term describes a network of connected food chains?
Antwort
a food web
Karte 876
Frage
Which term describes the total producer energy-capture rate?
Antwort
gross primary productivity
Karte 877
Frage
Which term describes producer biomass gain after respiration?
Antwort
net primary productivity
Karte 878
Frage
What is ecological productivity?
Antwort
The rate of biomass or energy production per unit area or volume.
Karte 879
Frage
What is a biogeochemical cycle?
Antwort
Movement of an element or compound through organisms and the physical environment.
Karte 880
Frage
Why is less energy available at each higher trophic level?
Antwort
Not all biomass is eaten or digested, and organisms use energy in respiration, movement, maintenance, and heat loss.
Karte 881
Frage
Why does energy flow rather than cycle through an ecosystem?
Antwort
Energy enters mainly as light and ultimately disperses as heat, which ecosystems cannot fully recycle.
Karte 882
Frage
Which term describes the rate of biomass or energy production?
Antwort
ecological productivity
Karte 883
Frage
Which term describes cycling of matter through living and nonliving reservoirs?
Antwort
a biogeochemical cycle
Karte 884
Frage
Why can matter cycle through an ecosystem?
Antwort
Atoms are conserved and repeatedly transferred among organisms, detritus, soil, water, and atmosphere.
Karte 885
Frage
Why is a pyramid of energy always upright?
Antwort
Usable energy decreases between trophic levels because every transfer includes losses.
Karte 886
Frage
How are gross and net primary productivity related?
Antwort
NPP = GPP − producer respiration.
Karte 887
Frage
How do decomposers support nutrient cycling?
Antwort
They break down dead material and wastes, releasing inorganic nutrients for reuse.
Karte 888
Frage
What processes move carbon rapidly between organisms and the atmosphere?
Antwort
Photosynthesis removes carbon dioxide; respiration, decomposition, and combustion release it.
Karte 889
Frage
Why is nitrogen fixation important?
Antwort
It converts atmospheric nitrogen gas into forms that can enter biological nitrogen metabolism.
Karte 890
Frage
How can excess nitrogen or phosphorus cause eutrophication?
Antwort
Nutrient enrichment drives algal growth; decomposition of the biomass consumes oxygen and can create hypoxic water.
Karte 891
Frage
Why can a persistent pollutant reach higher concentrations at higher trophic levels?
Antwort
Predators consume contaminant stored in many prey, and the substance is not readily broken down or excreted.
Karte 892
Frage
How is trophic-transfer efficiency calculated?
Antwort
Energy or biomass gained by the higher trophic level ÷ energy or biomass available at the lower level × 100%.
Karte 893
Frage
What is phenotypic variation?
Antwort
Differences in observable traits among individuals of a population.
Karte 894
Frage
What is heritable variation?
Antwort
Trait differences that can be transmitted genetically to offspring.
Karte 895
Frage
What is a selection pressure?
Antwort
An environmental factor causing differences in survival or reproduction among phenotypes.
Karte 896
Frage
What is relative fitness?
Antwort
An individual's reproductive success compared with others in the population.
Karte 897
Frage
Which term describes observable differences among individuals?
Antwort
phenotypic variation
Karte 898
Frage
Which term describes genetically transmissible trait differences?
Antwort
heritable variation
Karte 899
Frage
Which term describes an environmental factor producing differential reproductive success?
Antwort
a selection pressure
Karte 900
Frage
Which term describes reproductive success relative to other individuals?
Antwort
relative fitness
Karte 901
Frage
What is directional selection?
Antwort
Selection favoring one extreme phenotype and shifting a population's trait distribution.
Karte 902
Frage
What is stabilizing selection?
Antwort
Selection favoring intermediate phenotypes and acting against extremes.
Karte 903
Frage
What is disruptive selection?
Antwort
Selection favoring both extreme phenotypes over intermediates.
Karte 904
Frage
What is sexual selection?
Antwort
Selection arising from differences in mating success.
Karte 905
Frage
Which term describes selection shifting a trait toward one extreme?
Antwort
directional selection
Karte 906
Frage
Which term describes selection favoring intermediate phenotypes?
Antwort
stabilizing selection
Karte 907
Frage
Which term describes selection favoring both trait extremes?
Antwort
disruptive selection
Karte 908
Frage
Which term describes selection caused by unequal mating success?
Antwort
sexual selection
Karte 909
Frage
What conditions are required for natural selection?
Antwort
Individuals vary, some variation is heritable, more offspring are produced than can reproduce, and variants differ in reproductive success.
Karte 910
Frage
How does natural selection produce antibiotic-resistant bacterial populations?
Antwort
Existing resistant variants survive treatment and reproduce more than susceptible bacteria.
Karte 911
Frage
Does an antibiotic cause bacteria to mutate specifically toward resistance?
Antwort
No. Resistance variants arise without regard to need; treatment selects among them.
Karte 912
Frage
Can an individual become genetically adapted through natural selection?
Antwort
No. Selection acts on individuals, but adaptation is a population change across generations.
Karte 913
Frage
How does artificial selection differ from natural selection?
Antwort
Humans choose breeding traits in artificial selection; environmental conditions determine differential reproduction in natural selection.
Karte 914
Frage
How does natural selection change a population?
Antwort
Individuals with advantageous heritable variants leave more offspring, increasing those alleles over generations.
Karte 915
Frage
Why is fitness environment-dependent?
Antwort
A trait that improves reproduction in one environment may be neutral or costly in another.
Karte 916
Frage
How does genetic drift differ from natural selection?
Antwort
Drift changes allele frequencies by chance sampling; selection changes them through consistent fitness differences.
Karte 917
Frage
What is ecosystem stability?
Antwort
The capacity of an ecosystem to maintain or recover its structure and functions despite disturbance.
Karte 918
Frage
What is an ecological tipping point?
Antwort
A threshold beyond which feedbacks can drive a large and difficult-to-reverse ecosystem shift.
Karte 919
Frage
What is a mesocosm?
Antwort
A controlled, simplified ecosystem used to investigate ecological processes under more realistic conditions than a small laboratory vessel.
Karte 920
Frage
What is a sustainable yield?
Antwort
A harvest rate that can continue without causing long-term resource decline under prevailing conditions.
Karte 921
Frage
Which term describes the capacity of an ecosystem to persist or recover after disturbance?
Antwort
ecosystem stability
Karte 922
Frage
Which term describes a threshold triggering a major hard-to-reverse ecosystem shift?
Antwort
an ecological tipping point
Karte 923
Frage
Which term describes a controlled model ecosystem used for experiments?
Antwort
a mesocosm
Karte 924
Frage
Which term describes a harvest rate that avoids long-term depletion?
Antwort
a sustainable yield
Karte 925
Frage
What is eutrophication?
Antwort
Nutrient enrichment of water that stimulates excess primary production and can lead to oxygen depletion.
Karte 926
Frage
What is biomagnification?
Antwort
Increase in concentration of a persistent pollutant at successively higher trophic levels.
Karte 927
Frage
What is rewilding?
Antwort
Ecosystem restoration that rebuilds natural processes, species interactions, and self-sustaining ecological function.
Karte 928
Frage
What features can make an ecosystem more stable?
Antwort
Diverse functional roles, connected habitats, intact food webs, nutrient cycling, and balancing feedbacks can help the system resist or recover from disturbance.
Karte 929
Frage
Which term describes nutrient enrichment that can deplete oxygen in water?
Antwort
eutrophication
Karte 930
Frage
Which term describes increasing pollutant concentration up a food chain?
Antwort
biomagnification
Karte 931
Frage
Which term describes restoration focused on natural processes and self-sustaining ecosystems?
Antwort
rewilding
Karte 932
Frage
How could extensive Amazon deforestation push the ecosystem toward a tipping point?
Antwort
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.
Karte 933
Frage
What are a benefit and a limitation of using a mesocosm?
Antwort
It allows controlled experiments with interacting organisms, but its simplified scale cannot reproduce every process or long-term influence in a natural ecosystem.
Karte 934
Frage
Why should a fishery harvest below an uncertain maximum sustainable yield?
Antwort
Population estimates and recruitment vary, so a safety margin reduces the chance that error or a poor breeding year drives long-term decline.
Karte 935
Frage
How can intensive agriculture reduce ecosystem stability?
Antwort
Habitat loss, low crop diversity, soil degradation, heavy water use, pesticides, and nutrient runoff can weaken food webs and ecosystem processes.
Karte 936
Frage
Why can microplastic pollution harm aquatic ecosystems?
Antwort
Small persistent particles can be ingested, carry additives or other pollutants, damage feeding and tissues, and move through food webs.
Karte 937
Frage
How can rewilding improve ecosystem stability?
Antwort
Restoring native species, habitat connections, and natural disturbance or grazing processes can rebuild feedbacks and allow the ecosystem to maintain itself with less intervention.
Karte 938
Frage
What is the greenhouse effect?
Antwort
Warming caused when atmospheric gases absorb and re-emit outgoing infrared radiation.
Karte 939
Frage
What is a greenhouse gas?
Antwort
An atmospheric gas that absorbs infrared radiation at wavelengths emitted by Earth.
Karte 940
Frage
What is carbon dioxide (CO₂)?
Antwort
A long-lived greenhouse gas increased mainly by fossil-fuel combustion, cement production, and land-use change.
Karte 941
Frage
What is methane (CH₄)?
Antwort
A potent greenhouse gas emitted by sources including fossil-fuel systems, livestock, rice cultivation, wetlands, and waste.
Karte 942
Frage
Which term describes warming from absorption and re-emission of infrared radiation?
Antwort
the greenhouse effect
Karte 943
Frage
Which term describes an atmospheric infrared-absorbing gas?
Antwort
a greenhouse gas
Karte 944
Frage
Which term describes the long-lived greenhouse gas strongly increased by fossil fuels?
Antwort
carbon dioxide (CO₂)
Karte 945
Frage
Which term describes the potent short-lived greenhouse gas from biological and fossil sources?
Antwort
methane (CH₄)
Karte 946
Frage
What is albedo?
Antwort
The fraction of incoming radiation reflected by a surface.
Karte 947
Frage
What is a carbon sink?
Antwort
A reservoir that absorbs more carbon than it releases over a specified period.
Karte 948
Frage
What is ocean acidification?
Antwort
Decline in seawater pH caused mainly by absorption of human-emitted carbon dioxide.
Karte 949
Frage
What is climate change?
Antwort
A persistent change in the statistical patterns of climate over decades or longer.
Karte 950
Frage
Which term describes surface reflectivity?
Antwort
albedo
Karte 951
Frage
Which term describes a reservoir with net carbon uptake?
Antwort
a carbon sink
Karte 952
Frage
Which term describes seawater pH decline from absorbed carbon dioxide?
Antwort
ocean acidification
Karte 953
Frage
Which term describes long-term change in climate patterns?
Antwort
climate change
Karte 954
Frage
What is the enhanced greenhouse effect?
Antwort
Additional warming caused by human-driven increases in greenhouse-gas concentrations.
Karte 955
Frage
How do climate mitigation and climate adaptation differ?
Antwort
Mitigation limits the magnitude of climate change; adaptation reduces harm from changes that occur.
Karte 956
Frage
How does increasing greenhouse-gas concentration alter Earth's energy balance?
Antwort
Less outgoing infrared energy initially escapes to space, so the climate warms until energy balance is restored at a higher temperature.
Karte 957
Frage
How can melting ice amplify warming?
Antwort
Less bright ice lowers albedo, so darker land or water absorbs more solar energy and causes further warming.
Karte 958
Frage
How can climate change alter species distributions?
Antwort
Temperature, rainfall, seasons, sea level, and interactions shift, moving or shrinking areas with suitable conditions.
Karte 959
Frage
Why can ocean acidification harm calcifying organisms?
Antwort
Carbonate chemistry changes, reducing availability of carbonate ions used to build calcium-carbonate structures.
Karte 960
Frage
How can ecosystem protection contribute to climate mitigation?
Antwort
Protecting forests, wetlands, soils, and coastal habitats can avoid emissions and maintain or increase carbon storage.
960 Karten
IB Biology SL Flashcards: Complete Course Review
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