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