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