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