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