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