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