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