AP Biology Flashcards: Complete 8-Unit Course Review
Review all 8 AP Biology units with original flashcards for concepts, pathways, experimental design, data interpretation, and FRQ reasoning.
За това тесте
AP Biology Flashcards: Complete 8-Unit Course Review
The current AP Biology framework covers eight units, from chemistry of life through ecology. This 540-card deck turns that full course into short, original retrieval prompts, with science-practice reasoning mixed into the biology instead of parked in a separate section.
What the cards practice
The cards connect terms to functions, structures to consequences, pathway steps to inputs, outputs, locations, and regulation, and evidence to biological claims. Separate prompts cover useful reverse mappings when they are real study tasks—for example, identifying a process from its location or choosing the inference supported by a result. Short original scenarios also practice describing patterns, explaining mechanisms, predicting changes, justifying claims, setting up calculations, and evaluating evidence.
The deck does not mechanically reverse every definition or pathway. It leaves out copied exam material, scoring language, official figures, exhaustive protocols, broad essay prompts, textbook-specific trivia, and advanced-college details outside the current course boundary.
Learning order
The sequence follows Units 1–8. Within each unit it moves from prerequisites to processes, applications, experiments, data, and FRQ-style reasoning, while spacing close variants apart. Long-term spacing and interleaving are left to the review scheduler.
What still needs practice
Flashcards are useful for recall and small reasoning moves, but they cannot replace laboratory work, graph construction, extended data analysis, or timed multiple-choice and free-response practice. Use the deck beside class labs and full original practice questions.
Scope and provenance
The course boundary was reviewed on September 1, 2026 against the College Board AP Biology course page, the Fall 2025 Course and Exam Description, its current clarifications and corrections, the 2026–27 course-change table, and the current exam page. The selection, prompts, answers, examples, sequence, metadata, and cover are independently created from common biological knowledge and source checks. No exam questions, scoring guidelines, CED text, answer keys, or official figures were copied or transformed.
The Common knowledge · CC0 1.0 label applies to the original wording, organization, metadata, and generated media to the extent applicable rights exist. It does not claim ownership of biological facts, AP or College Board names, or third-party source material.
This independent, unofficial study deck is not affiliated with, endorsed by, or sponsored by College Board. AP and College Board names identify the course and exam only. Official requirements: https://apcentral.collegeboard.org/courses/ap-biology
Карти в това тесте
Карта 1
Въпрос
Why is a water molecule polar?
Отговор
Oxygen pulls shared electrons more strongly than hydrogen, giving oxygen a partial negative charge and the hydrogens partial positive charges.
Карта 2
Въпрос
Which elements make up most biological molecules?
Отговор
Carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur—often shortened to CHNOPS.
Карта 3
Въпрос
What is the relationship between a monomer and a polymer?
Отговор
Monomers are small building blocks; polymers are chains or networks made from repeated monomers.
Карта 4
Въпрос
What is a monosaccharide's main role in cells?
Отговор
It can provide quick energy and serve as a building block for larger carbohydrates.
Карта 5
Въпрос
Why do lipids mix poorly with water?
Отговор
Most of their bonds are nonpolar, so water cannot form favorable interactions with them.
Карта 6
Въпрос
What three parts make up a nucleotide?
Отговор
A five-carbon sugar, a phosphate group, and a nitrogenous base.
Карта 7
Въпрос
What parts of an amino acid vary and stay constant?
Отговор
The amino group, carboxyl group, hydrogen, and central carbon are shared; the side chain, or R group, varies.
Карта 8
Въпрос
What does pH measure?
Отговор
The negative logarithm of hydrogen-ion concentration; lower pH means more hydrogen ions.
Карта 9
Въпрос
What is a hydrogen bond in liquid water?
Отговор
A weak attraction between a partially positive hydrogen on one water molecule and a partially negative oxygen on another.
Карта 10
Въпрос
How does an unsaturated fatty acid differ from a saturated one?
Отговор
An unsaturated fatty acid has at least one carbon–carbon double bond; a saturated fatty acid has none.
Карта 11
Въпрос
What bond links amino acids in a polypeptide?
Отговор
A peptide bond.
Карта 12
Въпрос
What does dehydration synthesis do?
Отговор
It joins subunits with a covalent bond while removing the elements of water.
Карта 13
Въпрос
How does cohesion help water move through a plant?
Отговор
Hydrogen bonds keep water molecules linked, helping a continuous column rise through xylem.
Карта 14
Въпрос
How do plants and animals differ in short-term glucose storage?
Отговор
Plants store glucose mainly as starch; animals store it mainly as glycogen.
Карта 15
Въпрос
What determines a protein's primary structure?
Отговор
Its amino-acid sequence.
Карта 16
Въпрос
How does a cis double bond affect a fatty-acid tail?
Отговор
It introduces a bend that prevents neighboring tails from packing tightly.
Карта 17
Въпрос
How does adhesion support water transport in narrow tubes?
Отговор
Water sticks to polar surfaces, helping it resist gravity along cell walls.
Карта 18
Въпрос
Which base pairing distinguishes RNA from DNA?
Отговор
RNA uses uracil, so adenine pairs with uracil instead of thymine.
Карта 19
Въпрос
What stabilizes common protein secondary structures?
Отговор
Hydrogen bonds between atoms in the polypeptide backbone.
Карта 20
Въпрос
Why can carbon form so many biological structures?
Отговор
It has four valence electrons and can form four stable covalent bonds, including chains, branches, and rings.
Карта 21
Въпрос
Why can some insects stand on water?
Отговор
Cohesion among surface water molecules creates high surface tension.
Карта 22
Въпрос
What does hydrolysis do to a biological polymer?
Отговор
It adds the elements of water to break a covalent bond between subunits.
Карта 23
Въпрос
What carbohydrate strengthens plant cell walls?
Отговор
Cellulose.
Карта 24
Въпрос
Why are fats useful for long-term energy storage?
Отговор
Their many C–H bonds store substantial chemical energy, and hydrophobic storage adds little water mass.
Карта 25
Въпрос
How does water buffer rapid temperature change?
Отговор
Breaking and forming many hydrogen bonds absorbs or releases substantial heat, giving water a high specific heat.
Карта 26
Въпрос
What does antiparallel mean for a DNA double helix?
Отговор
Its two strands run in opposite directions: one 5′→3′ and the other 3′→5′.
Карта 27
Въпрос
What mainly drives a protein's tertiary structure?
Отговор
Interactions among side chains, including hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges.
Карта 28
Въпрос
What is a trace element?
Отговор
An element an organism needs in very small amounts, such as iron in many electron-transfer proteins.
Карта 29
Въпрос
Why does sweating cool an organism?
Отговор
The fastest water molecules escape as vapor, carrying heat away from the surface.
Карта 30
Въпрос
A cell builds a polysaccharide from sugars. Is water consumed or released?
Отговор
Released. Forming each linkage by dehydration removes water.
Карта 31
Въпрос
Why can branching help a storage polysaccharide release glucose quickly?
Отговор
More branch ends give enzymes more sites to work at once.
Карта 32
Въпрос
What makes a phospholipid amphipathic?
Отговор
It has a polar, hydrophilic head and nonpolar, hydrophobic tails.
Карта 33
Въпрос
Where is biological information encoded in a nucleic acid?
Отговор
In the linear sequence of nucleotide bases.
Карта 34
Въпрос
What is quaternary protein structure?
Отговор
The arrangement of two or more polypeptide subunits into one functional protein.
Карта 35
Въпрос
Why does ice float on liquid water?
Отговор
Stable hydrogen bonds hold ice molecules in an open lattice, making ice less dense than liquid water.
Карта 36
Въпрос
How does electronegativity affect a covalent bond?
Отговор
A difference in attraction for electrons makes electron sharing unequal and can create a polar bond.
Карта 37
Въпрос
A digestive reaction adds water while splitting a macromolecule. What reaction is this?
Отговор
Hydrolysis.
Карта 38
Въпрос
What links monosaccharides in a polysaccharide?
Отговор
Glycosidic covalent bonds.
Карта 39
Въпрос
Why do phospholipids form bilayers in water?
Отговор
Hydrophilic heads face water while hydrophobic tails cluster away from it.
Карта 40
Въпрос
To which end are nucleotides added during nucleic-acid synthesis?
Отговор
The 3′ end of the growing strand.
Карта 41
Въпрос
Why can one amino-acid substitution change protein function?
Отговор
It can alter side-chain interactions, folding, stability, or an active or binding site.
Карта 42
Въпрос
How does a buffer resist a pH change?
Отговор
It can accept added hydrogen ions or donate them when hydrogen-ion concentration falls.
Карта 43
Въпрос
Why is water a useful solvent for cells?
Отговор
Its partial charges surround ions and other polar molecules, separating and dispersing them.
Карта 44
Въпрос
Why do functional groups matter in organic molecules?
Отговор
They give carbon skeletons predictable chemical properties, such as polarity, acidity, or reactivity.
Карта 45
Въпрос
Why can two polymers built from similar monomers have different functions?
Отговор
Their monomer sequence, branching, length, and three-dimensional shape can differ.
Карта 46
Въпрос
A seedling consumes stored starch. What happens to the starch?
Отговор
Hydrolysis breaks it into smaller sugars that can enter energy pathways.
Карта 47
Въпрос
What are two biological roles of steroids?
Отговор
Some act as signaling molecules, and cholesterol helps stabilize animal cell membranes.
Карта 48
Въпрос
What bond forms the backbone of a nucleic-acid strand?
Отговор
Covalent phosphodiester bonds link the sugar of one nucleotide to the phosphate of the next.
Карта 49
Въпрос
What does denaturation do to a protein?
Отговор
It disrupts the protein's three-dimensional shape and often its function without usually breaking the primary peptide chain.
Карта 50
Въпрос
An enzyme works best near pH 7 but slows at pH 3. What is a likely explanation?
Отговор
Extra hydrogen ions changed charges and interactions that maintain the enzyme's active shape.
Карта 51
Въпрос
What structure encloses every cell?
Отговор
A plasma membrane.
Карта 52
Въпрос
What is the nucleus's main function?
Отговор
It houses most eukaryotic DNA and is a major site of DNA replication and transcription.
Карта 53
Въпрос
Why does surface-area-to-volume ratio fall as a cell grows?
Отговор
Volume increases with the cube of length, while surface area increases with the square.
Карта 54
Въпрос
What does the fluid mosaic model describe?
Отговор
A dynamic phospholipid bilayer containing mobile proteins, sterols, and carbohydrates.
Карта 55
Въпрос
What drives simple diffusion?
Отговор
Random molecular motion produces net movement from higher to lower concentration.
Карта 56
Въпрос
How does active transport differ from facilitated diffusion?
Отговор
Active transport moves a substance against its gradient using energy; facilitated diffusion moves it down a gradient.
Карта 57
Въпрос
Why does compartmentalization increase cellular efficiency?
Отговор
It concentrates enzymes and substrates and maintains distinct conditions for different reactions.
Карта 58
Въпрос
When should a light microscope be preferred over an electron microscope?
Отговор
When observing living cells or dynamic processes at lower resolution.
Карта 59
Въпрос
What does the nucleolus produce?
Отговор
Ribosomal RNA and early ribosome subunits.
Карта 60
Въпрос
Does passive transport require direct cellular energy?
Отговор
No. It moves substances down an electrochemical or concentration gradient.
Карта 61
Въпрос
What feature separates prokaryotic from eukaryotic cells?
Отговор
Eukaryotic cells have a membrane-bound nucleus and other membrane-bound organelles; prokaryotic cells do not.
Карта 62
Въпрос
Which membrane region blocks most ions and polar molecules?
Отговор
The hydrophobic interior formed by phospholipid tails.
Карта 63
Въпрос
What happens on rough endoplasmic reticulum?
Отговор
Bound ribosomes make proteins for secretion, membranes, or the endomembrane system.
Карта 64
Въпрос
How does facilitated diffusion differ from simple diffusion?
Отговор
It uses a channel or carrier protein but still moves a substance down its gradient.
Карта 65
Въпрос
Where is prokaryotic DNA usually located?
Отговор
In a nucleoid region rather than inside a membrane-bound nucleus.
Карта 66
Въпрос
How does cholesterol affect an animal membrane?
Отговор
It buffers fluidity, limiting excess movement when warm and preventing tight packing when cool.
Карта 67
Въпрос
What does smooth endoplasmic reticulum do?
Отговор
It synthesizes lipids, detoxifies some compounds, and stores calcium in specialized cells.
Карта 68
Въпрос
What determines a channel protein's selectivity?
Отговор
Its pore size, shape, charge, and gating behavior.
Карта 69
Въпрос
What does the sodium–potassium pump accomplish?
Отговор
Using ATP, it exports three sodium ions and imports two potassium ions per cycle.
Карта 70
Въпрос
What do ribosomes do in both prokaryotic and eukaryotic cells?
Отговор
They translate mRNA into polypeptides.
Карта 71
Въпрос
What is the Golgi apparatus's role?
Отговор
It modifies, sorts, and packages proteins and lipids arriving from the endoplasmic reticulum.
Карта 72
Въпрос
What is osmosis?
Отговор
Net movement of water across a selectively permeable membrane toward lower free-water concentration.
Карта 73
Въпрос
Why does a high surface-area-to-volume ratio help a cell?
Отговор
It provides more membrane area per unit of cytoplasm for exchange with the environment.
Карта 74
Въпрос
How do unsaturated phospholipid tails affect membrane fluidity?
Отговор
Their bends reduce tight packing, usually increasing fluidity.
Карта 75
Въпрос
Trace a secreted protein after translation begins.
Отговор
Rough ER → transport vesicle → Golgi → secretory vesicle → plasma membrane.
Карта 76
Въпрос
What happens to an animal cell in a hypotonic solution?
Отговор
Water enters; the cell swells and may lyse.
Карта 77
Въпрос
What is cotransport?
Отговор
The downhill movement of one substance powers the uphill transport of another through the same protein.
Карта 78
Въпрос
What is the main role of a cell wall?
Отговор
It provides structural support and helps prevent excessive expansion.
Карта 79
Въпрос
What do lysosomes do?
Отговор
Their hydrolytic enzymes digest macromolecules and recycle damaged cell parts in an acidic compartment.
Карта 80
Въпрос
What happens to an animal cell in a hypertonic solution?
Отговор
Water leaves; the cell shrinks.
Карта 81
Въпрос
How do intestinal microvilli improve absorption?
Отговор
They increase membrane surface area without greatly increasing cell volume.
Карта 82
Въпрос
What can an integral membrane protein do?
Отговор
It can transport substances, receive signals, catalyze reactions, or anchor cell structures.
Карта 83
Въпрос
What is a central vacuole's major role in a plant cell?
Отговор
It stores solutes and water and helps maintain turgor pressure.
Карта 84
Въпрос
What happens to a plant cell in a hypotonic solution?
Отговор
Water enters and turgor pressure rises; the cell wall helps prevent bursting.
Карта 85
Въпрос
How can a proton gradient power sucrose uptake in a plant cell?
Отговор
Protons flow down their gradient through a symporter that carries sucrose uphill.
Карта 86
Въпрос
What evidence supports the endosymbiotic origin of mitochondria?
Отговор
They have double membranes, circular DNA, bacterial-like ribosomes, and divide independently by a similar process.
Карта 87
Въпрос
Which overall energy-conversion pathway mainly occurs in mitochondria?
Отговор
Most stages of aerobic cellular respiration and ATP production.
Карта 88
Въпрос
What happens to a plant cell in a hypertonic solution?
Отговор
Water leaves, turgor falls, and the membrane may pull from the wall during plasmolysis.
Карта 89
Въпрос
Why can't a standard light microscope resolve a ribosome clearly?
Отговор
A ribosome is smaller than the microscope's diffraction-limited resolution.
Карта 90
Въпрос
How do bacterial and plant cell walls differ?
Отговор
Bacterial walls usually contain peptidoglycan; plant walls contain cellulose.
Карта 91
Въпрос
Which overall energy-conversion pathway occurs in chloroplasts?
Отговор
Photosynthesis: converting light energy into chemical energy and fixing carbon.
Карта 92
Въпрос
A cubical cell doubles each side length. How do surface area and volume change?
Отговор
Surface area increases 4-fold; volume increases 8-fold.
Карта 93
Въпрос
What is the role of membrane carbohydrates?
Отговор
They help cells recognize and interact with one another.
Карта 94
Въпрос
What is water potential?
Отговор
A measure predicting water movement; water moves from higher to lower water potential.
Карта 95
Въпрос
How do microtubules support a cell?
Отговор
They resist compression, form tracks for motors, and build structures such as spindles, cilia, and flagella.
Карта 96
Въпрос
What is endocytosis?
Отговор
The plasma membrane folds inward to bring material into the cell in a vesicle.
Карта 97
Въпрос
What evidence supports the endosymbiotic origin of chloroplasts?
Отговор
They share bacterial-like DNA, ribosomes, division, and a double membrane consistent with engulfment.
Карта 98
Въпрос
In a membrane-permeability test, what is the independent variable?
Отговор
The factor deliberately changed, such as temperature or solute identity.
Карта 99
Въпрос
How do microfilaments support cell movement?
Отговор
Actin filaments interact with motor proteins to change cell shape, contract, and move materials.
Карта 100
Въпрос
What does the cytosol contain?
Отговор
Water, ions, small molecules, and proteins where many metabolic reactions occur.
Карта 101
Въпрос
Why can diffusion limit cell size?
Отговор
As dimensions grow, molecules must travel farther, while exchange area does not keep pace with metabolic volume.
Карта 102
Въпрос
What does selective permeability mean?
Отговор
The membrane allows some substances to cross more readily than others.
Карта 103
Въпрос
What is an intermediate filament's general role?
Отговор
It provides durable mechanical strength and helps anchor structures.
Карта 104
Въпрос
How does adding a nonpenetrating solute affect water potential?
Отговор
It makes solute potential, and usually total water potential, more negative.
Карта 105
Въпрос
What is exocytosis?
Отговор
A vesicle fuses with the plasma membrane and releases contents outside the cell.
Карта 106
Въпрос
Why can lysosomal enzymes digest safely inside a cell?
Отговор
A membrane isolates the acidic enzymes from most cytosolic components.
Карта 107
Въпрос
Why include an untreated membrane sample in an experiment?
Отговор
It provides a control baseline for judging the treatment's effect.
Карта 108
Въпрос
Why doesn't cell size alone identify whether a cell is prokaryotic?
Отговор
Sizes overlap; the presence or absence of internal membrane-bound structures is stronger evidence.
Карта 109
Въпрос
Why are organelle interactions important?
Отговор
Cell functions often require products to move through several specialized compartments rather than one organelle working alone.
Карта 110
Въпрос
What graph would show a size constraint clearly?
Отговор
Plot cell size on the x-axis and surface-area-to-volume ratio on the y-axis; the ratio should decline as size rises.
Карта 111
Въпрос
Which molecules cross a phospholipid bilayer most easily without proteins?
Отговор
Small nonpolar molecules, such as oxygen and carbon dioxide.
Карта 112
Въпрос
Two solutions have equal water potential. What is the net water movement?
Отговор
None, although water molecules still move both ways.
Карта 113
Въпрос
Why is ATP loss likely to disrupt ion balance?
Отговор
ATP-powered pumps stop maintaining gradients, so passive leaks move ions toward equilibrium.
Карта 114
Въпрос
How does folding an internal membrane help an organelle?
Отговор
It increases surface area for membrane-bound reactions without a matching increase in volume.
Карта 115
Въпрос
A dye leaves heated cells faster than unheated cells. What conclusion is supported?
Отговор
Heating increased membrane permeability under the tested conditions; the data alone do not identify the exact molecular damage.
Карта 116
Въпрос
What does an enzyme change in a reaction?
Отговор
It lowers activation energy, increasing reaction rate without changing the reaction's overall free-energy change.
Карта 117
Въпрос
What makes a reaction exergonic?
Отговор
It releases free energy and has a negative change in free energy under the stated conditions.
Карта 118
Въпрос
What are the overall inputs and outputs of photosynthesis?
Отговор
Carbon dioxide and water use light energy to produce carbohydrate and oxygen.
Карта 119
Въпрос
What are the overall reactants and products of aerobic cellular respiration?
Отговор
Organic fuel and oxygen are converted mainly to carbon dioxide, water, and ATP, with heat released.
Карта 120
Въпрос
How should reaction rate be calculated from product data?
Отговор
Divide the change in product amount by the elapsed time.
Карта 121
Въпрос
What makes an enzyme substrate-specific?
Отговор
The active site's shape and chemical properties favor particular substrates.
Карта 122
Въпрос
Where do the light reactions occur?
Отговор
In the thylakoid membranes of chloroplasts.
Карта 123
Въпрос
Where does glycolysis occur?
Отговор
In the cytosol.
Карта 124
Въпрос
What makes a reaction endergonic?
Отговор
It requires a net input of free energy and has a positive change in free energy.
Карта 125
Въпрос
What is induced fit?
Отговор
Substrate binding shifts the enzyme's shape into a form that better supports catalysis.
Карта 126
Въпрос
Where does the Calvin cycle occur?
Отговор
In the chloroplast stroma.
Карта 127
Въпрос
What does glycolysis produce per glucose?
Отговор
Two pyruvate, a net two ATP, and two NADH.
Карта 128
Въпрос
How can cells drive an endergonic reaction?
Отговор
They couple it to a sufficiently exergonic reaction so the combined free-energy change is negative.
Карта 129
Въпрос
Why isn't an enzyme consumed by the reaction it catalyzes?
Отговор
It returns to a reusable form after products leave the active site.
Карта 130
Въпрос
What do photosynthetic pigments do?
Отговор
They absorb particular wavelengths and transfer excitation energy into the light reactions.
Карта 131
Въпрос
Does glycolysis require oxygen directly?
Отговор
No. It can run without oxygen if NAD⁺ is regenerated.
Карта 132
Въпрос
What does ATP hydrolysis commonly provide?
Отговор
Usable free energy and a phosphate group that can change a molecule's reactivity or protein shape.
Карта 133
Въпрос
How does substrate concentration affect rate at low concentrations?
Отговор
Rate usually rises because more substrate molecules collide with available active sites.
Карта 134
Въпрос
Why do chlorophyll-containing leaves reflect green light?
Отговор
Chlorophyll absorbs green wavelengths less strongly than red and blue wavelengths.
Карта 135
Въпрос
Where does pyruvate oxidation occur in a eukaryotic cell?
Отговор
In the mitochondrial matrix.
Карта 136
Въпрос
Why is ATP called an energy-coupling molecule?
Отговор
Its hydrolysis links energy-releasing processes to cellular work.
Карта 137
Въпрос
Why does enzyme rate plateau at high substrate concentration?
Отговор
Most active sites are occupied, so enzyme amount becomes limiting.
Карта 138
Въпрос
What is photolysis of water?
Отговор
Light-driven splitting of water that supplies electrons and protons and releases oxygen.
Карта 139
Въпрос
What happens during pyruvate oxidation?
Отговор
Each pyruvate becomes acetyl-CoA, releasing carbon dioxide and reducing NAD⁺ to NADH.
Карта 140
Въпрос
Why measure an initial enzyme rate?
Отговор
Substrate depletion and product buildup have had less time to distort the rate.
Карта 141
Въпрос
How can high temperature reduce enzyme activity?
Отговор
Heat can disrupt interactions that maintain the enzyme's functional shape.
Карта 142
Въпрос
What is photosystem II's key contribution?
Отговор
It excites electrons and replaces them by oxidizing water.
Карта 143
Въпрос
Where does the citric acid cycle occur in eukaryotes?
Отговор
In the mitochondrial matrix.
Карта 144
Въпрос
What is oxidation?
Отговор
Loss of electrons, often accompanied by loss of hydrogen or gain of oxygen.
Карта 145
Въпрос
Why does each enzyme have an optimal pH range?
Отговор
pH changes charges on amino-acid side chains and can alter binding or folding.
Карта 146
Въпрос
What does the photosynthetic electron transport chain build?
Отговор
A proton gradient across the thylakoid membrane.
Карта 147
Въпрос
What is the citric acid cycle's main energy role?
Отговор
It oxidizes acetyl groups and transfers electrons to NADH and FADH₂, making a small amount of ATP.
Карта 148
Въпрос
In a photosynthesis experiment, why keep leaf area constant?
Отговор
Leaf area affects light capture and gas exchange, so changing it could confound the tested factor.
Карта 149
Въпрос
How does a competitive inhibitor reduce enzyme activity?
Отговор
It competes with substrate for the active site.
Карта 150
Въпрос
How does chloroplast ATP synthase make ATP?
Отговор
Protons flow from the thylakoid space to the stroma through ATP synthase, driving phosphorylation of ADP.
Карта 151
Въпрос
Where is the respiratory electron transport chain located in eukaryotes?
Отговор
In the inner mitochondrial membrane.
Карта 152
Въпрос
What is reduction?
Отговор
Gain of electrons, often accompanied by gain of hydrogen or loss of oxygen.
Карта 153
Въпрос
How can extra substrate weaken competitive inhibition?
Отговор
More substrate increases the chance that substrate, rather than inhibitor, occupies the active site.
Карта 154
Въпрос
What is photosystem I's key contribution?
Отговор
It re-energizes electrons used to reduce NADP⁺ to NADPH.
Карта 155
Въпрос
What is oxygen's role in aerobic respiration?
Отговор
It is the final electron acceptor and combines with electrons and protons to form water.
Карта 156
Въпрос
A respiration graph gets steeper after temperature rises. What does the slope show?
Отговор
A higher rate of the measured respiratory change, such as oxygen consumption per unit time.
Карта 157
Въпрос
How does a noncompetitive inhibitor act?
Отговор
It binds away from the active site and changes enzyme activity, often by altering shape.
Карта 158
Въпрос
What products of the light reactions feed the Calvin cycle?
Отговор
ATP and NADPH.
Карта 159
Въпрос
How does electron transport create a proton gradient?
Отговор
Released electron energy pumps protons from the matrix to the intermembrane space.
Карта 160
Въпрос
What do NADH and FADH₂ carry?
Отговор
High-energy electrons and associated hydrogen used in energy-transfer pathways.
Карта 161
Въпрос
What is allosteric regulation?
Отговор
A regulator binds at one site and changes activity at another site on the protein.
Карта 162
Въпрос
What does carbon fixation accomplish?
Отговор
It incorporates inorganic carbon dioxide into an organic molecule.
Карта 163
Въпрос
What is oxidative phosphorylation?
Отговор
ATP production powered by electron transport and chemiosmosis.
Карта 164
Въпрос
Why use multiple biological replicates in a rate experiment?
Отговор
They reveal natural variation and make the estimated treatment effect more reliable.
Карта 165
Въпрос
What is fermentation's central purpose?
Отговор
It regenerates NAD⁺ so glycolysis can continue without an active electron transport chain.
Карта 166
Въпрос
How does feedback inhibition control a pathway?
Отговор
A pathway's end product inhibits an earlier enzyme, reducing unnecessary production.
Карта 167
Въпрос
What enzyme fixes carbon in the Calvin cycle?
Отговор
Rubisco.
Карта 168
Въпрос
How does mitochondrial ATP synthase make ATP?
Отговор
Protons flow into the matrix through ATP synthase, driving ADP phosphorylation.
Карта 169
Въпрос
Why do cells use stepwise electron transfers?
Отговор
They release energy in manageable increments that can be captured instead of lost mostly as heat.
Карта 170
Въпрос
What is a cofactor?
Отговор
A nonprotein helper, often a metal ion or small organic coenzyme, required for some enzymes to function.
Карта 171
Въпрос
What are the three broad phases of the Calvin cycle?
Отговор
Carbon fixation, reduction, and regeneration of the carbon-dioxide acceptor RuBP.
Карта 172
Въпрос
How does lactic-acid fermentation regenerate NAD⁺?
Отговор
NADH reduces pyruvate to lactate, returning electrons to form NAD⁺.
Карта 173
Въпрос
What is substrate-level phosphorylation?
Отговор
An enzyme transfers a phosphate directly from an intermediate to ADP.
Карта 174
Въпрос
Error bars overlap broadly between two treatments. What is a careful conclusion?
Отговор
The graph alone does not show a clear difference; a suitable statistical analysis and design context are still needed.
Карта 175
Въпрос
Why run an enzyme assay without enzyme?
Отговор
It measures the uncatalyzed background change and tests whether enzyme is required.
Карта 176
Въпрос
How does alcoholic fermentation regenerate NAD⁺?
Отговор
Pyruvate loses carbon dioxide, and the remaining compound is reduced to ethanol as NADH becomes NAD⁺.
Карта 177
Въпрос
What is G3P's role in photosynthesis?
Отговор
It is a three-carbon product that can leave the Calvin cycle and help build carbohydrates.
Карта 178
Въпрос
Why are mitochondrial cristae useful?
Отговор
They increase inner-membrane area for electron transport chains and ATP synthase.
Карта 179
Въпрос
What does phosphorylation often do to a molecule?
Отговор
It adds a phosphate group that can increase reactivity or alter a protein's shape and activity.
Карта 180
Въпрос
A mutation lowers an enzyme's maximum rate but not substrate binding. What is a plausible effect?
Отговор
It may impair a catalytic step or reduce the number of functional enzyme molecules.
Карта 181
Въпрос
Why must the Calvin cycle regenerate RuBP?
Отговор
RuBP is the carbon-dioxide acceptor needed for another turn of fixation.
Карта 182
Въпрос
A chemical lowers oxygen use but not glycolysis. Which stage is most directly implicated?
Отговор
Aerobic electron transport or a process supplying it, because glycolysis itself does not consume oxygen.
Карта 183
Въпрос
How would closed stomata affect photosynthesis?
Отговор
Carbon dioxide entry falls, which can limit carbon fixation even when light is available.
Карта 184
Въпрос
A plant receives green light only. Predict its photosynthetic rate.
Отговор
It will usually be lower than under equally intense red or blue light because common chlorophylls absorb green poorly.
Карта 185
Въпрос
Why does fermentation yield less ATP per glucose than aerobic respiration?
Отговор
It relies on glycolysis alone and leaves much of glucose's chemical energy in reduced end products.
Карта 186
Въпрос
How does low ATP affect respiration pathway activity?
Отговор
It usually relieves inhibition of key enzymes, increasing fuel oxidation and ATP production.
Карта 187
Въпрос
How can oxygen production estimate photosynthetic rate?
Отговор
Oxygen is a light-reaction product, so its production per unit time can serve as a rate proxy under controlled conditions.
Карта 188
Въпрос
What happens to electron transport if oxygen is removed?
Отговор
The chain backs up because electrons lack a final acceptor; NADH accumulates and oxidative phosphorylation stops.
Карта 189
Въпрос
Why does a light-response curve eventually level off?
Отговор
Another factor, such as carbon dioxide supply, temperature, or enzyme capacity, becomes limiting.
Карта 190
Въпрос
An uncoupler lets protons cross the inner mitochondrial membrane. What happens?
Отговор
The gradient weakens, ATP production falls, and more energy is released as heat even if electron transport continues.
Карта 191
Въпрос
What is direct-contact signaling?
Отговор
A membrane-bound molecule or cell junction communicates with an adjacent cell.
Карта 192
Въпрос
What are the three broad stages of cell signaling?
Отговор
Reception, transduction, and response.
Карта 193
Въпрос
How can a receptor mutation block a response even when ligand is present?
Отговор
The receptor may fail to bind ligand, change shape, or activate the first relay protein.
Карта 194
Въпрос
What is negative feedback?
Отговор
A response reduces the original stimulus, helping stabilize a variable near a functional range.
Карта 195
Въпрос
What happens during G1 phase?
Отговор
The cell grows, performs normal functions, and prepares for DNA replication.
Карта 196
Въпрос
Cells show response values of 2, 7, and 18 after rising ligand doses. Describe the trend.
Отговор
The response increases with ligand dose across the tested range.
Карта 197
Въпрос
What happens during reception?
Отговор
A ligand binds its receptor and changes the receptor's activity or shape.
Карта 198
Въпрос
What is paracrine signaling?
Отговор
A cell releases a local regulator that acts on nearby target cells.
Карта 199
Въпрос
What happens during S phase?
Отговор
DNA is replicated, producing sister chromatids for each chromosome.
Карта 200
Въпрос
A response occurs without ligand. What pathway defect is plausible?
Отговор
A receptor or downstream relay protein may be constitutively active.
Карта 201
Въпрос
What happens during signal transduction?
Отговор
Intracellular steps relay and often amplify information from the activated receptor.
Карта 202
Въпрос
What is synaptic signaling?
Отговор
A neuron releases neurotransmitter across a short synaptic gap to a target cell.
Карта 203
Въпрос
What happens during G2 phase?
Отговор
The cell grows, checks replicated DNA, and prepares the machinery for division.
Карта 204
Въпрос
Why compare receptor-positive and receptor-negative cells?
Отговор
The comparison tests whether the receptor is necessary for the observed response.
Карта 205
Въпрос
What counts as a cellular response?
Отговор
A change in gene expression, enzyme activity, ion flow, secretion, movement, division, or another cell behavior.
Карта 206
Въпрос
How does insulin participate in negative feedback?
Отговор
High blood glucose promotes insulin release, which lowers blood glucose and reduces the original stimulus.
Карта 207
Въпрос
What happens during mitosis?
Отговор
A eukaryotic nucleus separates duplicated chromosomes into two nuclei.
Карта 208
Въпрос
What is endocrine signaling?
Отговор
Hormones travel through circulatory fluid to target cells that may be far away.
Карта 209
Въпрос
What does a protein kinase do?
Отговор
It transfers a phosphate from ATP to a target protein.
Карта 210
Въпрос
A drug blocks a kinase, and the final response disappears. What is supported?
Отговор
The kinase is required somewhere in that pathway under the tested conditions.
Карта 211
Въпрос
What happens during cytokinesis?
Отговор
The cytoplasm divides to form separate daughter cells.
Карта 212
Въпрос
How does glucagon participate in glucose homeostasis?
Отговор
Low blood glucose promotes glucagon release, which raises blood glucose toward the normal range.
Карта 213
Въпрос
What does a protein phosphatase do?
Отговор
It removes a phosphate group from a target protein.
Карта 214
Въпрос
What is a ligand?
Отговор
A signaling molecule that binds specifically to a receptor.
Карта 215
Въпрос
What is the G1 checkpoint's broad role?
Отговор
It checks size, nutrients, growth signals, and DNA condition before replication.
Карта 216
Въпрос
Why can't one inhibitor experiment prove a protein's exact pathway position?
Отговор
Off-target effects and indirect dependencies can produce the same outcome.
Карта 217
Въпрос
Why are phosphorylation cascades reversible?
Отговор
Kinases add phosphates, while phosphatases remove them and reset pathway components.
Карта 218
Въпрос
What is positive feedback?
Отговор
A response strengthens the initiating stimulus until a separate event stops the loop.
Карта 219
Въпрос
What is the G2 checkpoint's broad role?
Отговор
It checks whether DNA replication is complete and damage is repaired before mitosis.
Карта 220
Въпрос
Why don't all cells respond to the same hormone?
Отговор
Only cells with a compatible receptor and response machinery can respond.
Карта 221
Въпрос
What is a second messenger?
Отговор
A small intracellular molecule or ion that relays a signal after receptor activation.
Карта 222
Въпрос
How can rescue with an active downstream protein map a pathway?
Отговор
If the response returns despite an upstream block, the rescued protein likely acts downstream of that block.
Карта 223
Въпрос
What does the spindle checkpoint verify?
Отговор
Every chromosome is correctly attached to spindle microtubules before sister chromatids separate.
Карта 224
Въпрос
Why is blood clotting a positive-feedback process?
Отговор
Activated platelets recruit and activate more platelets until the break is sealed.
Карта 225
Въпрос
Name two common second messengers.
Отговор
Cyclic AMP and calcium ions.
Карта 226
Въпрос
A mutant receptor binds ligand but never becomes phosphorylated. Predict downstream signaling.
Отговор
It will likely fall or disappear if receptor phosphorylation is required to recruit relay proteins.
Карта 227
Въпрос
How do cyclins regulate the cell cycle?
Отговор
Their concentrations rise and fall, activating cyclin-dependent kinases at specific stages.
Карта 228
Въпрос
Why must DNA replicate before mitosis?
Отговор
Each daughter nucleus needs a complete copy of the genome.
Карта 229
Въпрос
Where do receptors for many peptide hormones sit?
Отговор
In the plasma membrane, because these polar ligands do not readily cross the lipid bilayer.
Карта 230
Въпрос
How can a signaling pathway amplify a weak signal?
Отговор
One activated component activates many downstream molecules at successive steps.
Карта 231
Въпрос
What is the dependent variable in a ligand-dose experiment?
Отговор
The measured response, such as reporter activity, enzyme phosphorylation, or ion concentration.
Карта 232
Въпрос
What do cyclin-dependent kinases do?
Отговор
When paired with cyclins, they phosphorylate targets that drive cell-cycle transitions.
Карта 233
Въпрос
Why doesn't positive feedback usually maintain homeostasis by itself?
Отговор
It drives change away from the starting state and needs an external stop.
Карта 234
Въпрос
What is a G protein's signaling role?
Отговор
It switches activity when bound to GTP and relays information from certain membrane receptors to effectors.
Карта 235
Въпрос
How would you test whether calcium is required for a response?
Отговор
Block the calcium rise while keeping other conditions matched, then compare the response with a vehicle control.
Карта 236
Въпрос
What is apoptosis?
Отговор
Programmed cell death that dismantles a cell in a controlled way.
Карта 237
Въпрос
Where are receptors for many steroid hormones?
Отговор
Inside the cell, where lipid-soluble hormones can bind after crossing the membrane.
Карта 238
Въпрос
How can an ion-channel receptor create a rapid response?
Отговор
Ligand binding opens or closes a pore, quickly changing ion movement and membrane conditions.
Карта 239
Въпрос
Why test several ligand concentrations?
Отговор
A dose–response series can reveal sensitivity, saturation, and whether effects scale with ligand.
Карта 240
Въпрос
Why is apoptosis useful in multicellular organisms?
Отговор
It removes damaged, infected, or unneeded cells with limited harm to neighbors.
Карта 241
Въпрос
A thermostat-like pathway overshoots repeatedly. What defect is plausible?
Отговор
Delayed sensing or response can make negative feedback correct too late.
Карта 242
Въпрос
How can an intracellular receptor affect gene expression?
Отговор
The ligand–receptor complex can act directly or indirectly as a transcription regulator.
Карта 243
Въпрос
Cells lacking protein X divide despite DNA damage. Justify a checkpoint claim.
Отговор
Protein X likely supports a DNA-damage checkpoint because its absence links damage with continued division; rescue or pathway tests would strengthen the claim.
Карта 244
Въпрос
What aligns at the metaphase plate?
Отговор
Duplicated chromosomes attached to spindle microtubules from opposite poles.
Карта 245
Въпрос
How can failed checkpoints contribute to cancer?
Отговор
Cells with damage or abnormal signals can keep dividing instead of pausing or dying.
Карта 246
Въпрос
How can gap junctions support communication?
Отговор
They connect neighboring animal-cell cytoplasms so small molecules and ions can pass directly.
Карта 247
Въпрос
Why can the same ligand trigger different responses in two cell types?
Отговор
The cells can express different receptors, relay proteins, targets, or genes.
Карта 248
Въпрос
Two pathways share one relay protein. What can happen if that protein is blocked?
Отговор
Both responses may weaken, showing pathway crosstalk or a shared component.
Карта 249
Въпрос
During which mitotic stage do sister chromatids separate?
Отговор
Anaphase.
Карта 250
Въпрос
What defines a malignant tumor?
Отговор
Its cells invade surrounding tissue and may spread to distant sites.
Карта 251
Въпрос
How would loss of a feedback inhibitor affect a biosynthetic pathway?
Отговор
The pathway may stay active and overproduce its end product.
Карта 252
Въпрос
What ends a signaling response?
Отговор
Ligand removal, receptor inactivation, GTP hydrolysis, messenger breakdown, or dephosphorylation can shut it down.
Карта 253
Въпрос
A pathway diagram shows A activates B, and B inhibits C. Predict C after A activation.
Отговор
C activity should decrease, assuming the shown links are the relevant controlling interactions.
Карта 254
Въпрос
A phosphatase that normally turns off an activated relay protein is inhibited. Predict the effect on that pathway.
Отговор
Phosphorylated targets may stay active longer, extending or strengthening the response.
Карта 255
Въпрос
A drug prevents spindle formation. Where should the cycle stop?
Отговор
At the spindle checkpoint before anaphase, because chromosomes cannot attach correctly.
Карта 256
Въпрос
What is the purpose of meiosis?
Отговор
It produces haploid cells and reshuffles inherited alleles for sexual reproduction.
Карта 257
Въпрос
What is crossing over?
Отговор
Exchange of corresponding DNA segments between nonsister chromatids of homologous chromosomes.
Карта 258
Въпрос
What does Mendel's law of segregation describe?
Отговор
An individual's two alleles for a gene separate into different gametes.
Карта 259
Въпрос
Why do X-linked recessive traits often appear more frequently in XY individuals?
Отговор
They have only one X chromosome, so one recessive allele on it can determine the phenotype.
Карта 260
Въпрос
What is incomplete dominance?
Отговор
The heterozygote has a phenotype intermediate between the two homozygotes.
Карта 261
Въпрос
What does a chi-square goodness-of-fit test compare?
Отговор
Observed category counts with counts expected under a stated model.
Карта 262
Въпрос
What is a homologous chromosome pair?
Отговор
Two chromosomes carrying the same gene locations, one inherited from each parent, possibly with different alleles.
Карта 263
Въпрос
What does Mendel's law of independent assortment describe?
Отговор
Alleles of genes on different chromosomes, or far apart on one chromosome, assort independently during gamete formation.
Карта 264
Въпрос
What is genetic linkage?
Отговор
Genes close together on the same chromosome tend to be inherited together.
Карта 265
Въпрос
When does crossing over occur?
Отговор
During prophase I after homologs pair.
Карта 266
Въпрос
How do sister chromatids differ from homologous chromosomes?
Отговор
Sister chromatids are replicated copies of one chromosome; homologs are the maternal and paternal versions of the same chromosome type.
Карта 267
Въпрос
For Aa × Aa, what is the expected genotype ratio?
Отговор
1 AA : 2 Aa : 1 aa.
Карта 268
Въпрос
How can linked genes produce recombinant offspring?
Отговор
Crossing over can exchange DNA between the gene locations.
Карта 269
Въпрос
What is the usual null hypothesis for a Mendelian chi-square test?
Отговор
Any difference between observed and expected counts is due to chance sampling under the proposed inheritance model.
Карта 270
Въпрос
What happens to homologous chromosomes in meiosis I?
Отговор
They pair and then separate into different cells.
540 карти
AP Biology Flashcards: Complete 8-Unit Course Review
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Карта 271
Въпрос
For Aa × Aa with complete dominance, what is the expected phenotype ratio?
Отговор
3 dominant phenotype : 1 recessive phenotype.
Карта 272
Въпрос
How does crossing over increase variation?
Отговор
It creates chromosomes with new combinations of parental alleles.
Карта 273
Въпрос
What does recombination frequency estimate?
Отговор
Relative distance between linked genes; higher frequency generally means greater separation, up to the 50% limit.
Карта 274
Въпрос
What happens to sister chromatids in meiosis II?
Отговор
Their centromeres separate, and the chromatids move into different cells.
Карта 275
Въпрос
What rule finds the probability of either of two mutually exclusive outcomes?
Отговор
Add their individual probabilities.
Карта 276
Въпрос
What is codominance?
Отговор
Both alleles contribute distinct, detectable products or traits in the heterozygote.
Карта 277
Въпрос
How is a chi-square contribution calculated for one category?
Отговор
Subtract expected from observed, square the difference, and divide by expected.
Карта 278
Въпрос
When do homologous chromosomes pair as tetrads?
Отговор
During prophase I.
Карта 279
Въпрос
What rule finds the probability that independent events both occur?
Отговор
Multiply their individual probabilities.
Карта 280
Въпрос
What is independent assortment?
Отговор
Each homologous pair orients independently at metaphase I, producing many maternal–paternal chromosome combinations.
Карта 281
Въпрос
Why can't recombination frequency exceed 50%?
Отговор
At 50%, recombinant and parental combinations are equally common and the genes behave as if unlinked.
Карта 282
Въпрос
What aligns at the metaphase I plate?
Отговор
Homologous pairs, with each homolog attached toward an opposite pole.
Карта 283
Въпрос
What is a test cross?
Отговор
Crossing an individual with a dominant phenotype to a homozygous recessive individual to infer the unknown genotype.
Карта 284
Въпрос
How can one gene have multiple alleles?
Отговор
More than two allele forms can exist in the population, although one diploid individual carries at most two.
Карта 285
Въпрос
How are total chi-square and category contributions related?
Отговор
Total chi-square is the sum of all category contributions.
Карта 286
Въпрос
What separates during anaphase I?
Отговор
Homologous chromosomes; sister chromatids remain joined.
Карта 287
Въпрос
How does random fertilization increase variation?
Отговор
Any one genetically varied gamete from one parent can fuse with any compatible gamete from the other.
Карта 288
Въпрос
A test cross yields about half recessive offspring. What genotype is supported for the unknown parent?
Отговор
Heterozygous.
Карта 289
Въпрос
What is nondisjunction?
Отговор
Failure of homologous chromosomes or sister chromatids to separate normally.
Карта 290
Въпрос
What aligns during metaphase II?
Отговор
Individual duplicated chromosomes in each haploid cell.
Карта 291
Въпрос
What is polygenic inheritance?
Отговор
Multiple genes contribute to one trait, often producing continuous phenotypic variation.
Карта 292
Въпрос
For a simple goodness-of-fit test, how are degrees of freedom found?
Отговор
Number of categories minus one.
Карта 293
Въпрос
Which meiotic events create variation before fertilization?
Отговор
Crossing over and independent assortment.
Карта 294
Въпрос
How does ploidy change during meiosis?
Отговор
Homolog separation reduces diploid cells to haploid cells; meiosis II separates chromatids without another ploidy reduction.
Карта 295
Въпрос
What pedigree pattern often suggests a recessive trait?
Отговор
Unaffected parents can have an affected child, if both parents carry the allele.
Карта 296
Въпрос
How can meiotic nondisjunction affect gametes?
Отговор
It can produce gametes with an extra or missing chromosome.
Карта 297
Въпрос
What is pleiotropy?
Отговор
One gene influences multiple phenotypic traits.
Карта 298
Въпрос
Why is there no second DNA replication before meiosis II?
Отговор
The goal is to separate existing sister chromatids, not duplicate the genome again.
Карта 299
Въпрос
What does a p-value below the chosen threshold support?
Отговор
Rejecting the null model because the observed deviation would be unlikely if that model were correct.
Карта 300
Въпрос
Why are siblings genetically different even with the same parents?
Отговор
They inherit different allele combinations through crossing over, independent assortment, and random fertilization.
Карта 301
Въпрос
Why do small families often deviate from expected Mendelian ratios?
Отговор
Probability ratios describe long-run expectations; random sampling variation is large with few offspring.
Карта 302
Въпрос
A diploid cell has six chromosomes. How many chromosomes should each normal meiotic product have?
Отговор
Three.
Карта 303
Въпрос
A trisomic zygote forms after fertilization. What meiotic error is a likely cause?
Отговор
Nondisjunction produced a gamete carrying an extra copy of that chromosome.
Карта 304
Въпрос
Why can identical genotypes show different phenotypes?
Отговор
Environmental conditions and developmental variation can alter gene expression or trait development.
Карта 305
Въпрос
What does failing to reject a genetic null hypothesis mean?
Отговор
The data do not show a significant departure from the model; they do not prove the model true.
Карта 306
Въпрос
How do DNA and RNA sugars differ?
Отговор
DNA contains deoxyribose; RNA contains ribose.
Карта 307
Въпрос
What does semiconservative DNA replication produce?
Отговор
Each daughter DNA molecule contains one original strand and one newly synthesized strand.
Карта 308
Въпрос
What is transcription?
Отговор
Synthesis of RNA using DNA as a template.
Карта 309
Въпрос
What is a point mutation?
Отговор
A change affecting one nucleotide pair.
Карта 310
Въпрос
What is an operon?
Отговор
A group of prokaryotic genes controlled together and transcribed from one promoter.
Карта 311
Въпрос
Why can muscle and nerve cells differ despite having the same genome?
Отговор
They express different sets and amounts of genes.
Карта 312
Въпрос
What must a virus use from its host?
Отговор
Host resources and at least some host-cell machinery to copy or express its genome and produce new particles.
Карта 313
Въпрос
What does PCR do?
Отговор
It amplifies a chosen DNA region through repeated cycles of strand separation, primer binding, and extension.
Карта 314
Въпрос
What enzyme performs transcription?
Отговор
RNA polymerase.
Карта 315
Въпрос
What does helicase do during replication?
Отговор
It unwinds the double helix and separates the template strands.
Карта 316
Въпрос
How does a repressor reduce transcription?
Отговор
It binds regulatory DNA and blocks or hinders transcription machinery.
Карта 317
Въпрос
What is a silent mutation?
Отговор
A nucleotide change that does not change the encoded amino acid.
Карта 318
Въпрос
What does a promoter do?
Отговор
It marks where transcription machinery assembles and helps set the transcription start and direction.
Карта 319
Въпрос
What does topoisomerase do ahead of a replication fork?
Отговор
It relieves twisting strain caused by DNA unwinding.
Карта 320
Въпрос
How does an inducer affect an inducible operon?
Отговор
It disables the repressor or otherwise turns transcription on when the pathway's substrate is present.
Карта 321
Въпрос
How do DNA and RNA bases differ?
Отговор
DNA uses thymine, while RNA uses uracil; both also use adenine, cytosine, and guanine.
Карта 322
Въпрос
Which DNA strand does RNA polymerase read?
Отговор
The template strand, read 3′→5′ while RNA is built 5′→3′.
Карта 323
Въпрос
Why is an RNA primer needed for DNA replication?
Отговор
DNA polymerase can extend an existing 3′ end but cannot start a strand from nothing.
Карта 324
Въпрос
How does a corepressor affect a repressible operon?
Отговор
It activates a repressor, turning off genes when the pathway's end product is abundant.
Карта 325
Въпрос
What is a missense mutation?
Отговор
A nucleotide change that substitutes one amino acid for another.
Карта 326
Въпрос
How does an mRNA sequence relate to the coding DNA strand?
Отговор
It matches the coding strand except RNA has uracil in place of thymine.
Карта 327
Въпрос
What does primase do?
Отговор
It builds short RNA primers.
Карта 328
Въпрос
Why is the lac operon strongly expressed when lactose is present and glucose is scarce?
Отговор
Lactose relieves repression, while low glucose supports positive activation of transcription.
Карта 329
Въпрос
Why are primers essential in PCR?
Отговор
They define the target boundaries and provide 3′ ends for DNA polymerase.
Карта 330
Въпрос
What is the primary RNA transcript in a eukaryote?
Отговор
The initial RNA copy before processing.
Карта 331
Въпрос
In which direction does DNA polymerase synthesize DNA?
Отговор
5′→3′ by adding nucleotides to a 3′ end.
Карта 332
Въпрос
Why is the trp operon usually off when tryptophan is abundant?
Отговор
Tryptophan acts as a corepressor, enabling repression of biosynthetic genes.
Карта 333
Въпрос
What holds complementary DNA bases together?
Отговор
Hydrogen bonds: adenine pairs with thymine, and cytosine pairs with guanine.
Карта 334
Въпрос
What happens during RNA splicing?
Отговор
Introns are removed and exons are joined.
Карта 335
Въпрос
Why is the leading strand synthesized continuously?
Отговор
Its template orientation lets polymerase follow the replication fork while synthesizing 5′→3′.
Карта 336
Въпрос
How can histone acetylation affect transcription?
Отговор
It often loosens chromatin and makes DNA more accessible to transcription machinery.
Карта 337
Въпрос
What is a nonsense mutation?
Отговор
A nucleotide change that creates a premature stop codon.
Карта 338
Въпрос
What do the 5′ cap and poly-A tail help do?
Отговор
They protect eukaryotic mRNA and support export and translation.
Карта 339
Въпрос
Why is the lagging strand synthesized in fragments?
Отговор
Its template orientation forces repeated 5′→3′ synthesis away from the moving fork.
Карта 340
Въпрос
How can DNA methylation near a promoter affect transcription?
Отговор
It often reduces transcription by limiting access or recruiting repressive proteins.
Карта 341
Въпрос
How does gel electrophoresis separate DNA fragments?
Отговор
An electric field pulls negatively charged DNA through a matrix; smaller fragments usually travel farther.
Карта 342
Въпрос
How can alternative splicing increase protein diversity?
Отговор
Different exon combinations from one transcript can produce different mRNAs and polypeptides.
Карта 343
Въпрос
What are Okazaki fragments?
Отговор
Short DNA segments made on the lagging strand.
Карта 344
Въпрос
What does a transcription factor do?
Отговор
It binds regulatory DNA and helps increase or decrease transcription of specific genes.
Карта 345
Въпрос
Why are DNA strands antiparallel?
Отговор
Their sugar–phosphate backbones run in opposite 5′→3′ directions.
Карта 346
Въпрос
What is translation?
Отговор
Ribosomes use an mRNA codon sequence to build a polypeptide.
Карта 347
Въпрос
What does DNA ligase do?
Отговор
It seals breaks in the sugar–phosphate backbone, joining DNA fragments.
Карта 348
Въпрос
What is a frameshift mutation?
Отговор
An insertion or deletion not in multiples of three that shifts downstream codon grouping.
Карта 349
Въпрос
How can an enhancer influence a distant promoter?
Отговор
DNA looping brings enhancer-bound activators near the transcription machinery.
Карта 350
Въпрос
What does a codon specify?
Отговор
An amino acid or a translation stop signal.
Карта 351
Въпрос
What do restriction enzymes do?
Отговор
They cut DNA at particular recognition sequences.
Карта 352
Въпрос
What gives a nucleic-acid strand its 5′ and 3′ ends?
Отговор
The chemical groups on the sugar: a 5′ phosphate end and a 3′ hydroxyl end.
Карта 353
Въпрос
How does proofreading improve replication accuracy?
Отговор
DNA polymerases detect and replace many incorrectly paired nucleotides.
Карта 354
Въпрос
What does a tRNA anticodon do?
Отговор
It base-pairs with an mRNA codon so the attached amino acid is placed correctly.
Карта 355
Въпрос
Why can a promoter mutation affect protein amount?
Отговор
It can change transcription-factor or RNA-polymerase binding and alter transcription rate.
Карта 356
Въпрос
How can microRNA reduce gene expression?
Отговор
It base-pairs with target mRNA and promotes degradation or blocks translation.
Карта 357
Въпрос
What maintains a differentiated cell's identity?
Отговор
Stable regulatory networks and chromatin states keep characteristic genes active or silent.
Карта 358
Въпрос
What are the ribosome's broad roles?
Отговор
It positions mRNA and tRNAs and catalyzes peptide-bond formation.
Карта 359
Въпрос
How can an RNA virus generate genetic variation quickly?
Отговор
Many viral RNA polymerases lack strong proofreading, so replication introduces mutations frequently.
Карта 360
Въпрос
What can bacterial transformation demonstrate?
Отговор
Cells can take up external DNA and express a selectable or observable trait.
Карта 361
Въпрос
Why is RNA usually more structurally varied than double-stranded DNA?
Отговор
A single RNA strand can fold back on itself through internal base pairing.
Карта 362
Въпрос
What usually marks translation initiation?
Отговор
A start codon positioned with an initiator tRNA and ribosomal subunits.
Карта 363
Въпрос
What problem do telomeres help solve?
Отговор
They protect chromosome ends from losing essential genes during repeated linear-DNA replication.
Карта 364
Въпрос
Why can an intron splice-site mutation affect protein sequence?
Отговор
Incorrect splicing can remove exon sequence or retain intron sequence in the mature mRNA.
Карта 365
Въпрос
How can protein degradation regulate a pathway quickly?
Отговор
Destroying a key protein lowers its activity without waiting for transcription to change.
Карта 366
Въпрос
What happens at a stop codon?
Отговор
A release factor ends translation and frees the polypeptide.
Карта 367
Въпрос
How can a signal change cell specialization?
Отговор
It can activate transcription factors that launch a new gene-expression program.
Карта 368
Въпрос
What is a retrovirus's information flow?
Отговор
Viral RNA is reverse-transcribed into DNA, which can integrate into the host genome.
Карта 369
Въпрос
What does DNA sequencing reveal directly?
Отговор
The order of nucleotides in the analyzed DNA; biological effects require further interpretation.
Карта 370
Въпрос
Why is the genetic code called redundant?
Отговор
More than one codon can specify the same amino acid.
Карта 371
Въпрос
Where does nucleotide sequence store information?
Отговор
The order of bases encodes information that can be copied, transcribed, or translated.
Карта 372
Въпрос
Why is replication called bidirectional?
Отговор
Two forks usually move away from each origin in opposite directions.
Карта 373
Въпрос
Why doesn't every DNA mutation change phenotype?
Отговор
It may occur outside a functional sequence, be silent, have a mild effect, or be masked by another allele or environment.
Карта 374
Въпрос
How does a free ribosome's product usually differ from a rough-ER ribosome's product?
Отговор
Free ribosomes often make cytosolic proteins; ER-bound ribosomes make many secreted, membrane, and endomembrane proteins.
Карта 375
Въпрос
Why can one signal coordinate many genes?
Отговор
A shared transcription regulator or signaling pathway can control multiple target promoters.
Карта 376
Въпрос
Why does cell specialization depend on selective gene expression rather than gene loss?
Отговор
Most specialized cells retain the genome but use only the genes needed for their role.
Карта 377
Въпрос
Why are viruses not described as independently living cells?
Отговор
They lack cellular metabolism and cannot reproduce without a host cell.
Карта 378
Въпрос
A coding DNA triplet is 5′-ATG-3′. What is the matching mRNA codon?
Отговор
5′-AUG-3′.
Карта 379
Въпрос
A PCR band is absent. Why isn't gene absence the only explanation?
Отговор
Poor DNA quality, wrong primers, inhibitors, or failed reaction conditions can also prevent amplification.
Карта 380
Въпрос
Why can protein function require steps after translation?
Отговор
The polypeptide may need folding, cleavage, chemical modification, or assembly with other subunits.
Карта 381
Въпрос
How do fossils support evolution?
Отговор
They document organisms and transitions through time, including appearance, change, and extinction.
Карта 382
Въпрос
What conditions are required for natural selection?
Отговор
Individuals vary, some variation is heritable, and variants differ in survival or reproductive success in that environment.
Карта 383
Въпрос
What is artificial selection?
Отговор
Humans choose which organisms reproduce based on desired heritable traits.
Карта 384
Въпрос
What does an allele frequency measure?
Отговор
The fraction of all copies of a gene in a population represented by one allele.
Карта 385
Въпрос
What does a node on a phylogenetic tree represent?
Отговор
A common ancestor where descendant lineages diverge.
Карта 386
Въпрос
What is biological speciation?
Отговор
Evolution of reproductive isolation between populations, producing independently evolving lineages.
Карта 387
Въпрос
What is extinction?
Отговор
Permanent loss of a species when no living members remain.
Карта 388
Въпрос
A pesticide-treated population becomes mostly resistant. What evidence distinguishes selection from acclimation?
Отговор
Resistance should be heritable and increase across generations through differential reproduction, not just appear temporarily in exposed individuals.
Карта 389
Въпрос
What changes during evolution by natural selection?
Отговор
Allele frequencies in a population across generations.
Карта 390
Въпрос
For two alleles under Hardy–Weinberg notation, what does p + q equal?
Отговор
1.
Карта 391
Въпрос
What is a clade?
Отговор
An ancestor and all of its descendants.
Карта 392
Въпрос
What does homologous anatomy suggest?
Отговор
Similar underlying structures with different functions can indicate inheritance from a common ancestor.
Карта 393
Въпрос
Do individual organisms evolve by natural selection?
Отговор
No. Individuals are selected; populations evolve as inherited variants change in frequency.
Карта 394
Въпрос
Under Hardy–Weinberg equilibrium, what does p² represent?
Отговор
Expected frequency of one homozygous genotype.
Карта 395
Въпрос
What is a shared derived character?
Отговор
A trait that evolved in a common ancestor and helps identify one of its descendant clades.
Карта 396
Въпрос
What is mutation's evolutionary role?
Отговор
It creates new alleles, the ultimate source of new genetic variation.
Карта 397
Въпрос
What is biological fitness?
Отговор
Relative contribution of viable, reproducing offspring to the next generation in a particular environment.
Карта 398
Въпрос
Under Hardy–Weinberg equilibrium, what does 2pq represent?
Отговор
Expected frequency of heterozygotes.
Карта 399
Въпрос
Which two tips on a tree are most closely related?
Отговор
Those sharing the most recent common ancestor, regardless of how close their names appear on the page.
Карта 400
Въпрос
What is a vestigial structure?
Отговор
A reduced feature inherited from ancestors that has lost much or all of its earlier function.
Карта 401
Въпрос
What is an adaptation?
Отговор
A heritable trait that became common because it improved fitness in past environments.
Карта 402
Въпрос
Under Hardy–Weinberg equilibrium, what does q² represent?
Отговор
Expected frequency of the other homozygous genotype.
Карта 403
Въпрос
How does recombination affect evolution?
Отговор
It reshuffles existing alleles into new combinations but does not itself create new alleles.
Карта 404
Въпрос
Does rotating branches around a node change relationships?
Отговор
No. The branching pattern stays the same.
Карта 405
Въпрос
Why isn't an adaptation always beneficial in every setting?
Отговор
Fitness effects depend on the environment and can involve tradeoffs.
Карта 406
Въпрос
What are the Hardy–Weinberg assumptions?
Отговор
A very large population, random mating, no mutation, no migration, and no natural selection at the locus.
Карта 407
Въпрос
How can embryological similarities support common ancestry?
Отговор
Shared developmental patterns can reflect inherited developmental genes and pathways.
Карта 408
Въпрос
What is gene flow?
Отговор
Movement of alleles between populations through migration and reproduction.
Карта 409
Въпрос
Does natural selection create needed mutations?
Отговор
No. Mutations arise without regard to need; selection changes the frequencies of their inherited effects.
Карта 410
Въпрос
Why is Hardy–Weinberg equilibrium useful?
Отговор
It provides a null model for detecting or reasoning about evolutionary change.
Карта 411
Въпрос
Does left-to-right tip order show evolutionary progress?
Отговор
No. Tip order is a drawing choice, not a ranking from primitive to advanced.
Карта 412
Въпрос
What is allopatric speciation?
Отговор
Geographic separation reduces gene flow, allowing populations to diverge.
Карта 413
Въпрос
What is directional selection?
Отговор
Selection favors one end of a phenotypic range, shifting the population mean.
Карта 414
Въпрос
If q² = 0.09, what is q?
Отговор
0.30.
Карта 415
Въпрос
Why is DNA sequence similarity evidence for relatedness?
Отговор
Related lineages inherit sequences from common ancestors, with differences accumulating over time.
Карта 416
Въпрос
How does gene flow often affect differences between populations?
Отговор
It tends to make allele frequencies more similar.
Карта 417
Въпрос
What is stabilizing selection?
Отговор
Selection favors intermediate phenotypes and removes extremes.
Карта 418
Въпрос
If q = 0.30, what is p?
Отговор
0.70.
Карта 419
Въпрос
What can branch length mean?
Отговор
Only what the figure defines—sometimes time or amount of change, and sometimes nothing quantitative.
Карта 420
Въпрос
What is sympatric speciation?
Отговор
Reproductive isolation evolves without geographic separation, for example through polyploidy or strong niche and mating differences.
Карта 421
Въпрос
What is disruptive selection?
Отговор
Selection favors both extremes over intermediate phenotypes.
Карта 422
Въпрос
If p = 0.70 and q = 0.30, what is 2pq?
Отговор
0.42.
Карта 423
Въпрос
Why include an untreated population in a selection experiment?
Отговор
It shows how allele or trait frequencies change without the selective treatment.
Карта 424
Въпрос
Why is the nearly universal genetic code evidence of common ancestry?
Отговор
A deeply conserved information system is most simply explained by inheritance from early shared ancestors.
Карта 425
Въпрос
What is balancing selection?
Отговор
Natural selection that maintains two or more alleles in a population, such as through heterozygote advantage or selection that varies across environments.
Карта 426
Въпрос
What is genetic drift?
Отговор
Random change in allele frequencies caused by chance sampling across generations.
Карта 427
Въпрос
If 16% of a Hardy–Weinberg population shows a recessive phenotype, what is q?
Отговор
0.40, because q is the square root of 0.16.
Карта 428
Въпрос
Why use an outgroup in tree analysis?
Отговор
It helps infer which character states are ancestral versus derived in the focal group.
Карта 429
Въпрос
What is a prezygotic barrier?
Отговор
A barrier that prevents mating or fertilization.
Карта 430
Въпрос
Allele A rises from 0.20 to 0.45. Describe the evolutionary result.
Отговор
The population evolved at that locus because allele frequency changed.
Карта 431
Въпрос
How does biogeography support evolution?
Отговор
Species distributions often match isolation history, dispersal, and descent from nearby ancestors.
Карта 432
Въпрос
What is sexual selection?
Отговор
Differences in mating success drive changes in traits that affect mate attraction or competition.
Карта 433
Въпрос
When is genetic drift strongest?
Отговор
In small populations.
Карта 434
Въпрос
Why can a rare recessive allele persist?
Отговор
Selection cannot remove copies hidden in heterozygotes as efficiently as copies expressed in homozygotes.
Карта 435
Въпрос
How can molecular data revise a phylogenetic tree?
Отговор
Sequence comparisons can reveal relationships not obvious from morphology or distinguish convergence from homology.
Карта 436
Въпрос
What is a postzygotic barrier?
Отговор
A barrier that reduces hybrid survival, fertility, or later-generation success after fertilization.
Карта 437
Въпрос
How can rapid environmental change increase extinction risk?
Отговор
Populations may lack enough suitable variation or time to adapt or move.
Карта 438
Въпрос
A small island population loses alleles after a storm. Which mechanism is most direct?
Отговор
Genetic drift through a bottleneck.
Карта 439
Въпрос
What is convergent evolution?
Отговор
Unrelated lineages independently evolve similar traits under similar selective pressures.
Карта 440
Въпрос
Why can antibiotic resistance spread rapidly?
Отговор
Treatment strongly favors resistant variants already present or newly introduced, which leave more descendants.
Карта 441
Въпрос
What is a bottleneck effect?
Отговор
A sharp population reduction leaves a random, often less diverse sample of the original gene pool.
Карта 442
Въпрос
How do genotype counts yield allele frequency?
Отговор
Count two copies from each homozygote and one from each heterozygote, then divide by twice the number of diploid individuals.
Карта 443
Въпрос
What is maximum parsimony in tree building?
Отговор
Preferring the tree that requires the fewest evolutionary changes under the model.
Карта 444
Въпрос
How can different breeding times isolate populations?
Отговор
Temporal isolation prevents individuals from mating even when they share a location.
Карта 445
Въпрос
Why can mass extinctions reshape evolution?
Отговор
They remove many lineages and open ecological opportunities for survivors.
Карта 446
Въпрос
Two similar traits evolved on distant tree branches. What explanation should be evaluated?
Отговор
Convergent evolution under similar selection, alongside the possibility of an incorrect tree or unrecognized homology.
Карта 447
Въпрос
Why are analogous structures weak evidence of close ancestry?
Отговор
Their similar function may have evolved independently rather than from the same ancestral structure.
Карта 448
Въпрос
Why doesn't natural selection produce perfection?
Отговор
It works with existing variation under tradeoffs, historical constraints, chance, and changing environments.
Карта 449
Въпрос
What is a founder effect?
Отговор
A new population starts from a small, nonrepresentative sample of a source population.
Карта 450
Въпрос
Observed genotypes differ from Hardy–Weinberg expectations. What is supported?
Отговор
At least one model assumption may not hold, or sampling error may matter; the deviation alone does not identify the cause.
Карта 451
Въпрос
Why is a phylogenetic tree a hypothesis?
Отговор
It is an evidence-based reconstruction that can change when new data or methods appear.
Карта 452
Въпрос
How can behavioral differences cause isolation?
Отговор
Different courtship signals reduce mating between populations.
Карта 453
Въпрос
What evidence can test origin-of-life hypotheses?
Отговор
Chemistry experiments, geological records, molecular comparisons, and plausible self-replicating or membrane-forming systems.
Карта 454
Въпрос
How should fitness be compared in an experiment?
Отговор
Measure relative reproductive contribution, such as viable offspring, under the same environmental conditions.
Карта 455
Въпрос
What does the fossil record not provide?
Отговор
A complete sample of every organism or every transitional population.
Карта 456
Въпрос
How can a neutral trait change in frequency?
Отговор
Genetic drift can shift it by chance, especially in small populations.
Карта 457
Въпрос
How can drift reduce adaptive potential?
Отговор
It can remove alleles and lower genetic diversity needed under future environmental change.
Карта 458
Въпрос
Why does a large population support Hardy–Weinberg stability?
Отговор
Chance sampling has less effect on allele frequencies, reducing drift.
Карта 459
Въпрос
If A and B share a more recent node with each other than either shares with C, what does that mean?
Отговор
A and B are sister taxa and share a more recent common ancestor with each other than with C.
Карта 460
Въпрос
What is adaptive radiation?
Отговор
Rapid diversification of one ancestral lineage into species using different ecological roles.
Карта 461
Въпрос
What can experiments producing organic molecules from simple chemicals show?
Отговор
That some building blocks can form under modeled conditions; they do not recreate or prove the exact origin of life.
Карта 462
Въпрос
A correlation links beak size with survival. Why isn't causation settled?
Отговор
Other traits or habitats may covary with beak size; controlled or multivariable evidence is needed.
Карта 463
Въпрос
Why does agreement among fossils, anatomy, and molecules strengthen an evolutionary claim?
Отговор
Independent evidence types pointing to the same history make alternative explanations less plausible.
Карта 464
Въпрос
A drought favors deeper beaks. What must be measured to show selection?
Отговор
Heritable beak variation and differences in survival or reproduction linked to beak depth.
Карта 465
Въпрос
Why can artificial selection produce unintended traits?
Отговор
Selected genes may be linked to other alleles, and inbreeding can expose harmful recessive alleles.
Карта 466
Въпрос
What data are needed to test Hardy–Weinberg genotype expectations?
Отговор
Population genotype counts or reliable genotype frequencies for the locus.
Карта 467
Въпрос
Why doesn't one living species count as the ancestor of another on a typical tree?
Отговор
Living tips represent lineages that have both evolved since their shared ancestral lineage.
Карта 468
Въпрос
Why can reduced gene flow accelerate divergence?
Отговор
Populations retain separate mutations, drift independently, and respond to different selective pressures.
Карта 469
Въпрос
Why are ribozymes relevant to early-life hypotheses?
Отговор
RNA can both store information and catalyze reactions, offering a possible bridge before modern DNA–protein systems.
Карта 470
Въпрос
What makes an evolutionary argument strong?
Отговор
A clear claim, relevant population-level evidence, and reasoning that connects inheritance and differential reproduction to the observed change.
Карта 471
Въпрос
How can a directional response help an organism?
Отговор
Moving toward resources or away from hazards can improve survival and reproduction.
Карта 472
Въпрос
What is a trophic level?
Отговор
A feeding position in the flow of energy through an ecosystem.
Карта 473
Въпрос
What processes move carbon into and out of biological molecules?
Отговор
Photosynthesis fixes carbon; respiration, decomposition, and combustion release carbon dioxide.
Карта 474
Въпрос
What does exponential population growth assume?
Отговор
Resources are effectively unlimited and the per-capita growth rate stays constant.
Карта 475
Въпрос
What is a density-dependent limiting factor?
Отговор
Its effect strengthens as population density rises, such as competition, disease, or predation.
Карта 476
Въпрос
What is a keystone species?
Отговор
A species whose ecological effect is disproportionately large relative to its abundance.
Карта 477
Въпрос
What are three levels of biodiversity?
Отговор
Genetic diversity, species diversity, and ecosystem diversity.
Карта 478
Въпрос
What is the independent variable in a fertilizer–algae experiment?
Отговор
The fertilizer amount or nutrient concentration deliberately changed.
Карта 479
Въпрос
What shape represents exponential growth over time?
Отговор
A J-shaped curve.
Карта 480
Въпрос
What do primary producers do?
Отговор
They capture external energy and build organic molecules from inorganic carbon.
Карта 481
Въпрос
What is a density-independent limiting factor?
Отговор
Its effect is not primarily set by population density, such as a severe freeze or wildfire.
Карта 482
Въпрос
Why is nitrogen fixation necessary?
Отговор
Most organisms cannot use atmospheric nitrogen gas directly, so it must be converted to biologically available compounds.
Карта 483
Въпрос
What does logistic growth add to the exponential model?
Отговор
Growth slows as population size approaches carrying capacity.
Карта 484
Въпрос
What is gross primary productivity?
Отговор
The total rate at which producers capture energy in organic matter.
Карта 485
Въпрос
What is competition?
Отговор
An interaction in which organisms using the same limited resource reduce one another's access or fitness.
Карта 486
Въпрос
What is ecological succession?
Отговор
Change in community composition after new habitat forms or a disturbance alters an existing community.
Карта 487
Въпрос
What shape represents ideal logistic growth?
Отговор
An S-shaped curve.
Карта 488
Въпрос
What is net primary productivity?
Отговор
Gross primary productivity minus producers' respiratory energy use.
Карта 489
Въпрос
Why does genetic diversity matter for conservation?
Отговор
It increases the range of inherited responses available under disease or environmental change.
Карта 490
Въпрос
What organisms perform much biological nitrogen fixation?
Отговор
Certain prokaryotes, including free-living and symbiotic bacteria.
Карта 491
Въпрос
What is carrying capacity?
Отговор
The population size an environment can sustain over time under current conditions.
Карта 492
Въпрос
Why is net primary productivity important to consumers?
Отговор
It is the producer biomass and energy available for growth and the next trophic levels.
Карта 493
Въпрос
What is competitive exclusion?
Отговор
Species with identical limiting-resource niches cannot coexist indefinitely under stable conditions.
Карта 494
Въпрос
How do primary and secondary succession differ?
Отговор
Primary succession begins without developed soil; secondary succession begins where soil remains.
Карта 495
Въпрос
Why can carrying capacity change?
Отговор
Resources, habitat, climate, competitors, disease, and disturbance can change.
Карта 496
Въпрос
Why does available energy decline up a food chain?
Отговор
Organisms use much energy for metabolism and lose it as heat and waste rather than storing it as biomass.
Карта 497
Въпрос
What is an ecosystem service?
Отговор
A benefit people receive from ecosystems, such as pollination, water purification, soil formation, or climate regulation.
Карта 498
Въпрос
What does nitrification do?
Отговор
Microbes oxidize ammonium to nitrite and then nitrate.
Карта 499
Въпрос
What does per-capita growth rate measure?
Отговор
Population change per individual per unit time.
Карта 500
Въпрос
What is ecological efficiency?
Отговор
The percentage of energy or production transferred from one trophic level to the next.
Карта 501
Въпрос
What is resource partitioning?
Отговор
Competing species use different resources, places, or times, reducing direct overlap.
Карта 502
Въпрос
What is resilience in an ecosystem?
Отговор
The ability to recover structure or function after disturbance.
Карта 503
Въпрос
How is population growth estimated from births, deaths, immigration, and emigration?
Отговор
Births + immigration − deaths − emigration.
Карта 504
Въпрос
If producers store 10,000 kJ and primary consumers receive 10%, how much do they receive?
Отговор
1,000 kJ.
Карта 505
Въпрос
How does habitat fragmentation affect populations?
Отговор
It shrinks and isolates habitat, reducing movement and gene flow while increasing edge effects.
Карта 506
Въпрос
Why sample several sites within each habitat?
Отговор
Replication captures spatial variation and reduces the chance that one unusual site drives the result.
Карта 507
Въпрос
A population grows from 200 to 230 in one year. What is its percent growth?
Отговор
15%, because the increase of 30 divided by 200 is 0.15.
Карта 508
Въпрос
What is a circadian rhythm?
Отговор
An internal roughly 24-hour cycle that environmental cues can reset.
Карта 509
Въпрос
Why are food webs more realistic than simple food chains?
Отговор
Most species eat or are eaten by multiple species, creating connected pathways.
Карта 510
Въпрос
What does denitrification do?
Отговор
Microbes convert nitrate to nitrogen gases, returning nitrogen to the atmosphere.
Карта 511
Въпрос
What characterizes an r-selected life-history strategy?
Отговор
Many offspring, early reproduction, and relatively low investment per offspring in variable environments.
Карта 512
Въпрос
What is mutualism?
Отговор
An interaction that benefits both species.
Карта 513
Въпрос
What is resistance in an ecosystem?
Отговор
The ability to remain relatively unchanged during disturbance.
Карта 514
Въпрос
How can climate change shift species ranges?
Отговор
Organisms track suitable temperature, moisture, seasons, or interacting species when movement is possible.
Карта 515
Въпрос
What characterizes a K-selected life-history strategy?
Отговор
Fewer offspring, later reproduction, and higher investment per offspring near carrying capacity.
Карта 516
Въпрос
A population curve levels near 800. What does the model suggest?
Отговор
About 800 is the carrying capacity under those measured conditions, not a permanent universal value.
Карта 517
Въпрос
How can seasonal cues affect reproduction?
Отговор
Changes such as day length can trigger hormonal and behavioral shifts timed to favorable conditions.
Карта 518
Въпрос
What role do decomposers play?
Отговор
They break down dead material and waste, returning nutrients to forms other organisms can use.
Карта 519
Въпрос
Why can phosphorus limit ecosystems?
Отговор
It is essential but often released slowly from rocks and lacks a large atmospheric gas phase.
Карта 520
Въпрос
What does a Type I survivorship curve show?
Отговор
High survival through early and middle life, followed by a steep decline at older ages.
Карта 521
Въпрос
What is commensalism?
Отговор
One species benefits while the other has no clear benefit or harm.
Карта 522
Въпрос
Why can diversity improve ecosystem stability?
Отговор
Multiple species or response types can keep functions going when one component declines.
Карта 523
Въпрос
Why can overharvesting destabilize a population?
Отговор
Removal faster than replacement lowers abundance and can alter age structure or genetic diversity.
Карта 524
Въпрос
Predator and prey peaks alternate over time. What can the graph establish?
Отговор
Their abundances covary with a lag; the graph alone cannot prove the predator caused every prey change.
Карта 525
Въпрос
What is acclimation?
Отговор
A reversible phenotypic adjustment by an individual to an environmental change.
Карта 526
Въпрос
Does energy cycle through an ecosystem?
Отговор
No. Energy flows through and is ultimately dissipated as heat; matter cycles.
Карта 527
Въпрос
How does the water cycle connect ecosystems?
Отговор
Evaporation, transpiration, condensation, precipitation, runoff, and infiltration move water and dissolved materials.
Карта 528
Въпрос
What does a Type II survivorship curve show?
Отговор
A roughly constant mortality risk across ages.
Карта 529
Въпрос
What is parasitism?
Отговор
A parasite benefits while reducing its host's fitness.
Карта 530
Въпрос
What is an invasive species?
Отговор
A nonnative species that spreads and causes ecological, economic, or human-health harm.
Карта 531
Въпрос
How can a wildlife corridor help fragmented populations?
Отговор
It supports movement, recolonization, and gene flow between habitat patches.
Карта 532
Въпрос
How should biodiversity be compared when sample effort differs?
Отговор
Standardize sampling effort or use a method that accounts for unequal effort before comparing.
Карта 533
Въпрос
How does acclimation differ from adaptation?
Отговор
Acclimation occurs within an individual; adaptation is an inherited population change across generations.
Карта 534
Въпрос
How can removal of a top predator affect lower trophic levels?
Отговор
It can trigger a trophic cascade by changing prey abundance and the organisms prey consume.
Карта 535
Въпрос
Why can extra fertilizer cause low oxygen in water?
Отговор
Nutrient enrichment drives algal growth; decomposition then consumes dissolved oxygen.
Карта 536
Въпрос
What does a Type III survivorship curve show?
Отговор
High early mortality with much better survival among those reaching later stages.
Карта 537
Въпрос
How can predation maintain diversity?
Отговор
A predator can prevent one strong competitor from dominating the community.
Карта 538
Въпрос
How can disturbance increase or decrease diversity?
Отговор
Its effect depends on frequency and intensity; it may create habitat variety or eliminate sensitive species.
Карта 539
Въпрос
Why protect multiple habitats rather than one small reserve?
Отговор
Different habitats, disturbances, and climate trajectories preserve more species and ecological options.
Карта 540
Въпрос
A restoration site gains species but not nutrient cycling. How should success be evaluated?
Отговор
Use both composition and ecosystem-function measures; one metric alone gives an incomplete result.
540 карти
AP Biology Flashcards: Complete 8-Unit Course Review
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