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