Practice Test for AP Biology - 2

Question 1

Water molecules are attracted to the cellulose molecules lining the walls of xylem vessels in plants, allowing water to move upward against gravity. Which property of water best explains this interaction?

Accepted Answer

Adhesion, because water molecules are attracted to other polar molecules on different surfaces

Answer

Cohesion, because water molecules form hydrogen bonds with one another

Answer

High specific heat, because water resists temperature changes as it moves through the xylem

Answer

Surface tension, because water molecules at the air-water interface resist disruption

Question 2

A researcher adds a molecule structurally similar to an enzyme's natural substrate to a reaction mixture. The researcher observes that increasing substrate concentration progressively restores the reaction rate until it reaches normal V_max. Which type of inhibition is demonstrated?

Accepted Answer

Competitive inhibition, because the structurally similar inhibitor competes with the substrate for the active site and can be overcome by increased substrate concentration

Answer

Non-competitive inhibition, because the inhibitor binds to an allosteric site and permanently reduces V_max

Answer

Irreversible inhibition, because the inhibitor forms a covalent bond with the active site

Answer

Allosteric inhibition, because binding of the inhibitor changes the enzyme's quaternary structure

Question 3

A protein enzyme completely loses its ability to catalyze its target reaction after being heated to 90°C. Biochemical analysis confirms that the primary structure (amino acid sequence) is intact. Which of the following best explains why the enzyme can no longer function?

Accepted Answer

The tertiary structure of the enzyme has been disrupted by denaturation, altering the shape of the active site so it can no longer bind substrate

Answer

The primary structure of the enzyme has been permanently altered by covalent peptide bond breakage during heating

Answer

The substrate concentration in the reaction decreased as a result of the elevated temperature

Answer

The enzyme was completely hydrolyzed into individual amino acids, eliminating its catalytic activity

Question 4

A researcher measures the activity of pepsin (a digestive enzyme) at pH values of 1, 3, 5, 7, and 9. Pepsin activity peaks near pH 2 and declines sharply above pH 5. A colleague proposes that the decline in activity above pH 5 is caused by decreased substrate concentration rather than changes to the enzyme. Which of the following best evaluates this claim?

Accepted Answer

The claim is invalid because changes in pH alter the ionization states of amino acid R-groups at the active site, disrupting the enzyme's tertiary structure and substrate binding

Answer

The claim is valid because pH directly reduces the concentration of available substrate molecules in solution

Answer

The claim is valid because enzymes require high substrate concentrations to maintain catalytic function at any pH

Answer

The claim is invalid because temperature, not pH, is the primary variable controlling enzyme denaturation in this experiment

Question 5

A graph plots the rate of an enzyme-catalyzed reaction (y-axis) versus substrate concentration (x-axis). The curve rises steeply at low substrate concentrations and then levels off into a plateau at high substrate concentrations. What does the plateau represent?

Accepted Answer

All enzyme active sites are saturated, and the reaction is proceeding at maximum velocity (V_max); additional substrate cannot increase the rate further

Answer

The substrate molecules have been completely consumed by the reaction, halting further product formation

Answer

The enzyme has been denatured by the high concentration of substrate molecules

Answer

The activation energy of the reaction has been completely eliminated by the enzyme at high substrate concentrations

Question 6

Phospholipids spontaneously form bilayers in aqueous environments, with hydrophobic fatty acid tails oriented inward and hydrophilic phosphate head groups facing the aqueous environment. Which of the following best explains why the nonpolar tails are excluded from contact with water?

Accepted Answer

Nonpolar fatty acid tails are excluded from aqueous environments because water molecules form more energetically stable hydrogen bonds with each other than with nonpolar molecules, driving hydrophobic aggregation

Answer

The fatty acid tails carry phosphate groups that are repelled by the negative charges on water molecules

Answer

The charged phosphate head groups repel each other so forcefully that the nonpolar tails are pushed inward

Answer

Covalent bonds spontaneously form between the fatty acid tails of adjacent phospholipid molecules, holding the bilayer together

Question 7

A red blood cell is placed into a solution with a higher solute concentration than the cell's cytoplasm. Water exits the cell by osmosis, causing the cell to shrink (crenation). The solution surrounding the cell is best described as:

Accepted Answer

Hypertonic, because the solution has a higher solute concentration than the cell's interior, causing a net movement of water out of the cell

Answer

Hypotonic, because the solution has a lower solute concentration than the cell's interior

Answer

Isotonic, because water moves equally in both directions across the cell membrane

Answer

Isosmotic, because the osmotic pressure of the solution equals that of the cell's cytoplasm

Question 8

A researcher models cells as perfect cubes and calculates the surface area-to-volume (SA:V) ratio for cubes with side lengths of 1 cm, 2 cm, and 4 cm. The calculated SA:V ratios are 6, 3, and 1.5, respectively. Which of the following conclusions is best supported by this data?

Accepted Answer

As cell size increases, the SA:V ratio decreases, limiting the cell's ability to exchange materials, waste, and gases with its environment efficiently enough to sustain metabolic demand

Answer

Larger cells are more efficient at nutrient exchange because their greater absolute surface area allows more membrane transport proteins

Answer

Cell size does not meaningfully affect metabolic efficiency because cytoplasmic volume scales proportionally with surface area

Answer

Smaller cells are less efficient at nutrient exchange because they have a lower absolute surface area than larger cells

Question 9

Which of the following observations provides the strongest evidence for the endosymbiotic origin of mitochondria from an ancestral proteobacterium?

Accepted Answer

Mitochondria contain their own circular DNA and replicate by binary fission, both characteristics shared with free-living prokaryotes

Answer

Mitochondria are enclosed by a double membrane, the outer of which is derived from the host cell's endomembrane system

Answer

Mitochondria produce ATP, a molecule also produced by prokaryotic cells during cellular respiration

Answer

Mitochondria are found exclusively in eukaryotic cells and are absent from all prokaryotic organisms

Question 10

The sodium-potassium (Na⁺/K⁺) pump actively transports 3 Na⁺ out of and 2 K⁺ into the cell per ATP molecule hydrolyzed, maintaining the electrochemical gradient across the plasma membrane. If a toxin severely inhibits ATP production in the cell, which of the following consequences is most likely?

Accepted Answer

Na⁺ will accumulate inside the cell as the pump fails to export it, disrupting the electrochemical gradient necessary for normal cellular function

Answer

Na⁺ will accumulate outside the cell, hyperpolarizing the membrane beyond its normal resting potential

Answer

K⁺ will accumulate outside the cell as its concentration gradient drives diffusion in the reverse direction

Answer

The cell will switch to facilitated diffusion to maintain ionic gradients, compensating for the loss of active transport

Question 11

A researcher compares membrane fatty acid composition in bacteria grown at 37°C (Group 1) versus 15°C (Group 2). Analysis reveals that Group 2 bacteria have a significantly higher proportion of unsaturated fatty acids in their membrane phospholipids. Which of the following best explains this finding?

Accepted Answer

Unsaturated fatty acids have kinked hydrocarbon tails that prevent tight packing of phospholipids, maintaining membrane fluidity and function at low temperatures

Answer

Unsaturated fatty acids pack more tightly together at low temperatures, increasing membrane rigidity and reducing energy expenditure by the cell

Answer

Bacteria grown at low temperatures produce less ATP, reducing the availability of saturated fatty acids for membrane synthesis

Answer

Bacteria at low temperatures synthesize fewer total phospholipids, which automatically increases the relative proportion of unsaturated fatty acids

Question 12

Both a eukaryotic cell and a bacterial cell need to rapidly increase production of a specific protein in response to an extracellular signal. Which of the following correctly identifies a key mechanistic difference between these two cell types in accomplishing this?

Accepted Answer

Eukaryotic mRNA must be processed (5' cap addition, poly-A tail addition, intron splicing) and exported from the nucleus before translation, while bacterial mRNA can be translated by ribosomes immediately as it is being transcribed

Answer

Bacteria perform transcription in the nucleus and translation in the cytoplasm, while eukaryotes couple both processes in the cytoplasm

Answer

Eukaryotes require no post-translational protein modification, while bacteria must extensively modify all proteins before they become functional

Answer

Bacteria require a 5' cap and poly-A tail on mRNA before translation can initiate, while eukaryotes do not process their mRNA

Question 13

A secretory cell synthesizes digestive enzymes, packages them into membrane-bound vesicles in the Golgi apparatus, and then releases them into the extracellular space when the vesicle fuses with the plasma membrane. This process is correctly classified as:

Accepted Answer

Exocytosis, a bulk transport process in which secretory vesicles fuse with the plasma membrane to release their contents into the extracellular environment

Answer

Endocytosis, a process in which the cell membrane invaginates to internalize extracellular material into vesicles

Answer

Facilitated diffusion, because the enzymes move from high concentration inside the cell to lower concentration outside

Answer

Pinocytosis, the process by which cells take up extracellular fluid and dissolved solutes into small vesicles

Question 14

A student claims that the Calvin cycle directly uses light energy absorbed by chlorophyll to reduce CO₂ and produce G3P. Which of the following correctly evaluates this claim?

Accepted Answer

The claim is incorrect because the Calvin cycle uses ATP and NADPH produced by the light reactions as energy and reducing power, respectively; it does not directly require light

Answer

The claim is correct because light activates rubisco in the stroma, which directly drives the reduction of CO₂ to G3P

Answer

The claim is correct because light is absorbed by photosystems in the stroma where the Calvin cycle occurs

Answer

The claim is incorrect because the Calvin cycle occurs on the thylakoid membrane, not in the stroma, and does not interact with light-absorbing pigments

Question 15

A researcher compares ATP yield in cells supplied with glucose under aerobic versus anaerobic conditions. Cells under anaerobic conditions produce approximately 2 ATP per glucose, while aerobic cells produce approximately 30–32 ATP per glucose. Which of the following best explains this large difference?

Accepted Answer

Under anaerobic conditions, only glycolysis produces ATP; pyruvate oxidation, the Krebs cycle, and oxidative phosphorylation require oxygen as the final electron acceptor and do not proceed

Answer

Glycolysis does not occur under anaerobic conditions, so only fermentation generates the 2 ATP observed

Answer

Fermentation generates additional ATP molecules beyond glycolysis under anaerobic conditions, supplementing the reduced output

Answer

Anaerobic conditions increase the rate of glycolysis sufficiently to compensate for the loss of the Krebs cycle and oxidative phosphorylation

Question 16

C4 plants such as corn and sugarcane use a two-cell mechanism in which CO₂ is initially fixed into a 4-carbon oxaloacetate molecule in mesophyll cells, then transported to bundle sheath cells where CO₂ is released and enters the Calvin cycle. Which of the following best explains the adaptive advantage of this mechanism in hot, dry climates?

Accepted Answer

C4 plants concentrate CO₂ around rubisco in bundle sheath cells, suppressing rubisco's oxygenase activity and reducing wasteful photorespiration, thereby improving net carbon fixation efficiency in hot, dry conditions

Answer

C4 plants absorb more light energy per unit leaf area by using two types of chlorophyll not present in C3 plants

Answer

C4 plants produce more NADPH per CO₂ fixed because the 4-carbon intermediate carries additional high-energy electrons to bundle sheath cells

Answer

C4 plants eliminate the need for the Calvin cycle, reducing the overall ATP and NADPH expenditure required for carbon fixation

Question 17

A graph shows a positive linear relationship between the magnitude of the proton gradient across the inner mitochondrial membrane (x-axis) and the rate of ATP synthesis (y-axis). A researcher applies a chemical that makes the inner mitochondrial membrane freely permeable to H⁺ ions (a proton uncoupler). Which of the following best predicts the effect on ATP production?

Accepted Answer

The proton gradient would collapse because H⁺ ions would leak across the membrane without passing through ATP synthase, eliminating the electrochemical driving force for ATP synthesis and dramatically reducing ATP production

Answer

The rate of ATP synthesis would increase because protons can now flow more freely across the membrane, accelerating the rotation of ATP synthase

Answer

Substrate-level phosphorylation in glycolysis would also be inhibited because the proton gradient is required for glycolytic ATP production

Answer

The electron transport chain would cease to function because it requires a completely impermeable inner mitochondrial membrane to accept and donate electrons

Question 18

During intense anaerobic exercise, human skeletal muscle cells convert pyruvate to lactate using NADH. Which of the following best explains the primary function of this conversion?

Accepted Answer

The conversion regenerates NAD⁺ from NADH, allowing glycolysis to continue accepting electrons and producing ATP in the absence of oxygen

Answer

The conversion generates additional ATP molecules beyond those produced by glycolysis, increasing the cell's energy supply

Answer

The conversion transforms pyruvate into acetyl-CoA for entry into the Krebs cycle during anaerobic conditions

Answer

The conversion provides lactate as an alternative final electron acceptor in the electron transport chain

Question 19

A student states: “Both photosynthesis and cellular respiration produce carbon dioxide as a metabolic byproduct.” Which of the following correctly evaluates this statement?

Accepted Answer

The statement is incorrect because CO₂ is a reactant consumed during the Calvin cycle of photosynthesis, not a product; CO₂ is released as a byproduct only during cellular respiration (pyruvate oxidation and the Krebs cycle)

Answer

The statement is correct because CO₂ is released during both the light reactions of photosynthesis and glycolysis in cellular respiration

Answer

The statement is correct because all metabolic pathways that involve carbon-containing molecules ultimately release CO₂ as a waste product

Answer

The statement is incorrect because CO₂ is released exclusively during the light reactions of photosynthesis and not during cellular respiration

Question 20

A researcher isolates chloroplast stroma and maintains CO₂ availability but eliminates the supply of both ATP and NADPH to the preparation. Which of the following best predicts the effect on the Calvin cycle?

Accepted Answer

The Calvin cycle will halt entirely because ATP is required for the phosphorylation step that regenerates RuBP and NADPH is required for the reduction of 3-PGA to G3P

Answer

CO₂ fixation by rubisco will continue, but G3P will not be produced because NADPH is unavailable for reduction

Answer

RuBP will accumulate indefinitely because its regeneration from G3P is enhanced when ATP is absent

Answer

The light reactions will compensate by directly synthesizing G3P from CO₂ in the thylakoid membranes

Question 21

Which of the following correctly distinguishes substrate-level phosphorylation from oxidative phosphorylation in cellular respiration?

Accepted Answer

Substrate-level phosphorylation directly transfers a phosphate group from a high-energy substrate molecule to ADP, while oxidative phosphorylation uses the proton gradient generated by the electron transport chain to drive ATP synthase

Answer

Substrate-level phosphorylation requires oxygen as a final electron acceptor, while oxidative phosphorylation can occur under anaerobic conditions

Answer

Oxidative phosphorylation occurs exclusively in the cytoplasm during glycolysis, while substrate-level phosphorylation is confined to the inner mitochondrial membrane

Answer

Substrate-level phosphorylation accounts for the majority of ATP produced per glucose molecule, while oxidative phosphorylation produces only 2 ATP per cycle

Question 22

A researcher radioactively labels the two carbon atoms in a single acetyl-CoA molecule entering one turn of the Krebs cycle. After one complete turn, which of the following most accurately describes the fate of those labeled carbon atoms?

Accepted Answer

Two CO₂ molecules are released per turn of the Krebs cycle, but the labeled carbon atoms from acetyl-CoA are incorporated into Krebs cycle intermediates and are not necessarily the carbons released as CO₂ in that same turn

Answer

Both labeled carbon atoms from acetyl-CoA are released as CO₂ during the first complete turn of the Krebs cycle

Answer

Four CO₂ molecules are released from a single acetyl-CoA entry during one complete turn of the Krebs cycle

Answer

The labeled carbons from acetyl-CoA are permanently incorporated into oxaloacetate and are never released as CO₂

Question 23

A hormone binds to a G-protein coupled receptor on a target cell surface, activating adenylyl cyclase, which catalyzes the conversion of ATP to cAMP. The cAMP subsequently activates protein kinase A, which phosphorylates specific intracellular target proteins. In this signal transduction pathway, cAMP is best described as:

Accepted Answer

A second messenger that amplifies and relays the extracellular signal within the cell, activating downstream protein kinases without crossing the plasma membrane

Answer

A ligand that binds to the extracellular domain of the G-protein coupled receptor to initiate the signaling cascade

Answer

A G-protein subunit that directly activates adenylyl cyclase upon dissociation from the receptor complex

Answer

A transcription factor that directly enters the nucleus and activates gene expression in response to the hormonal signal

Question 24

A researcher discovers a somatic mutation in a human cell that inactivates the p53 protein. Under normal conditions, p53 activates DNA repair pathways at the G₁ checkpoint or triggers apoptosis when DNA damage is irreparable. Which of the following best predicts the most likely consequence of this mutation?

Accepted Answer

Cells with damaged DNA will bypass the G₁ checkpoint and continue dividing, potentially accumulating additional mutations that drive transformation to a malignant cancer cell

Answer

The affected cells will arrest permanently at the G₁ checkpoint, preventing all further cell division and tumor formation

Answer

The cells will undergo apoptosis at an elevated rate, significantly reducing the likelihood of tumor development

Answer

DNA replication will be completely inhibited because p53 is required for helicase activation at replication origins

Question 25

During meiosis I, homologous chromosomes physically exchange corresponding segments through a process called crossing over. Which of the following best explains how crossing over contributes to genetic diversity in a population?

Accepted Answer

Crossing over creates new combinations of alleles on individual chromosomes by exchanging segments between non-sister chromatids, producing gametes with genotypes that differ from either parental chromosome

Answer

Crossing over reduces chromosome number in each gamete by half, ensuring that each offspring is genetically unique from its parents

Answer

Crossing over selectively eliminates deleterious alleles from the homologous chromosome pair before they can be transmitted to offspring

Answer

Crossing over is required for proper chromosome segregation during anaphase II by physically linking homologs until they separate

Question 26

A cancer cell secretes a signaling molecule that binds to receptors on its own plasma membrane, stimulating the cell's own proliferation. This type of cell signaling is best classified as:

Accepted Answer

Autocrine signaling, because the cell produces a signaling molecule that binds to receptors on its own surface, stimulating a response in the same cell

Answer

Paracrine signaling, because the signaling molecule diffuses across short distances to nearby target cells

Answer

Endocrine signaling, because the growth factor is secreted into the bloodstream and travels to distant target cells

Answer

Juxtacrine signaling, because the growth factor is a membrane-bound ligand that requires direct cell-to-cell contact to activate its receptor

Question 27

During normal limb development in vertebrates, cells in the interdigital webbing are eliminated by programmed cell death (apoptosis), forming distinct digits. A mutation that prevents caspase activation in the interdigital cells would most likely result in which of the following?

Accepted Answer

Failure of the interdigital webbing to be removed, likely resulting in fused or webbed digits due to the absence of programmed cell death between the developing digits

Answer

An increased mitotic rate in limb bud cells, causing overgrowth and formation of extra digits

Answer

Premature apoptosis of the interdigital cells, causing incomplete formation of the digits themselves

Answer

Uncontrolled activation of proto-oncogenes in the limb bud cells, converting them to oncogenes and causing benign tumor formation

Question 28

A researcher examines a rapidly dividing tissue sample under a microscope and counts cells in each phase: Interphase 70%, Prophase 10%, Metaphase 8%, Anaphase 5%, Telophase 7%. Which of the following best explains why the largest proportion of cells are observed in interphase?

Accepted Answer

Interphase is by far the longest phase of the cell cycle (comprising G₁, S, and G₂); cells spend the most time in this phase, so a random snapshot will capture the highest proportion of cells there

Answer

Chromosomes are most condensed and visible during interphase, making those cells easier to identify and count under a microscope

Answer

More cells undergo DNA damage repair during interphase than during any other phase of the cell cycle, increasing cell retention in this phase

Answer

Cells in interphase divide at a slower rate than cells in prophase, causing an accumulation of cells in the interphase category

Question 29

A researcher treats a mammalian cell culture with a phosphatase inhibitor. Phosphatases are enzymes that remove phosphate groups from signaling proteins, terminating their activity. Which of the following best describes the expected effect on intracellular signal transduction?

Accepted Answer

Signal transduction pathways would be prolonged and potentially hyperactivated because phosphorylated signaling proteins would remain active longer in the absence of dephosphorylation

Answer

Signal transduction would be completely eliminated because phosphorylation of signaling proteins is required to initiate transduction cascades

Answer

The rate of ligand binding to cell-surface receptors would decrease, reducing the overall initiation of signaling cascades

Answer

Intracellular cAMP concentrations would decrease because phosphatases normally catalyze the synthesis of cAMP from ATP

Question 30

A cross between a true-breeding red-flowered plant (R¹R¹) and a true-breeding white-flowered plant (R²R²) produces all pink-flowered offspring (R¹R²). Which of the following best describes this pattern of inheritance?

Accepted Answer

Incomplete dominance, because neither allele is fully dominant over the other, and the heterozygous offspring display an intermediate blended phenotype

Answer

Codominance, because both the red and white alleles are simultaneously and separately expressed in the pink heterozygote

Answer

Epistasis, because the expression of one gene is masking the expression of the other gene controlling flower color

Answer

Complete dominance, because the red-pigment allele is partially expressed and produces color in the heterozygous condition

Practice Test for AP Biology - 2 Grade 10 MCQs & solutions - Free

MCQ Practice Test & Solutions: Practice Test for AP Biology - 2 (60 Questions)

Water molecules are attracted to the cellulose molecules lining the walls of xylem vessels in plants, allowing water to move upward against gravity. Which property of water best explains this interaction?

A researcher adds a molecule structurally similar to an enzyme's natural substrate to a reaction mixture. The researcher observes that increasing substrate concentration progressively restores the reaction rate until it reaches normal V_max. Which type of inhibition is demonstrated?

A protein enzyme completely loses its ability to catalyze its target reaction after being heated to 90°C. Biochemical analysis confirms that the primary structure (amino acid sequence) is intact. Which of the following best explains why the enzyme can no longer function?

A graph plots the rate of an enzyme-catalyzed reaction (y-axis) versus substrate concentration (x-axis). The curve rises steeply at low substrate concentrations and then levels off into a plateau at high substrate concentrations. What does the plateau represent?

Phospholipids spontaneously form bilayers in aqueous environments, with hydrophobic fatty acid tails oriented inward and hydrophilic phosphate head groups facing the aqueous environment. Which of the following best explains why the nonpolar tails are excluded from contact with water?

A red blood cell is placed into a solution with a higher solute concentration than the cell's cytoplasm. Water exits the cell by osmosis, causing the cell to shrink (crenation). The solution surrounding the cell is best described as:

A researcher models cells as perfect cubes and calculates the surface area-to-volume (SA:V) ratio for cubes with side lengths of 1 cm, 2 cm, and 4 cm. The calculated SA:V ratios are 6, 3, and 1.5, respectively. Which of the following conclusions is best supported by this data?

Which of the following observations provides the strongest evidence for the endosymbiotic origin of mitochondria from an ancestral proteobacterium?

Both a eukaryotic cell and a bacterial cell need to rapidly increase production of a specific protein in response to an extracellular signal. Which of the following correctly identifies a key mechanistic difference between these two cell types in accomplishing this?

A secretory cell synthesizes digestive enzymes, packages them into membrane-bound vesicles in the Golgi apparatus, and then releases them into the extracellular space when the vesicle fuses with the plasma membrane. This process is correctly classified as:

A student claims that the Calvin cycle directly uses light energy absorbed by chlorophyll to reduce CO₂ and produce G3P. Which of the following correctly evaluates this claim?

During intense anaerobic exercise, human skeletal muscle cells convert pyruvate to lactate using NADH. Which of the following best explains the primary function of this conversion?

A student states: “Both photosynthesis and cellular respiration produce carbon dioxide as a metabolic byproduct.” Which of the following correctly evaluates this statement?

A researcher isolates chloroplast stroma and maintains CO₂ availability but eliminates the supply of both ATP and NADPH to the preparation. Which of the following best predicts the effect on the Calvin cycle?

Which of the following correctly distinguishes substrate-level phosphorylation from oxidative phosphorylation in cellular respiration?

A researcher radioactively labels the two carbon atoms in a single acetyl-CoA molecule entering one turn of the Krebs cycle. After one complete turn, which of the following most accurately describes the fate of those labeled carbon atoms?

During meiosis I, homologous chromosomes physically exchange corresponding segments through a process called crossing over. Which of the following best explains how crossing over contributes to genetic diversity in a population?

A cancer cell secretes a signaling molecule that binds to receptors on its own plasma membrane, stimulating the cell's own proliferation. This type of cell signaling is best classified as:

During normal limb development in vertebrates, cells in the interdigital webbing are eliminated by programmed cell death (apoptosis), forming distinct digits. A mutation that prevents caspase activation in the interdigital cells would most likely result in which of the following?

A researcher examines a rapidly dividing tissue sample under a microscope and counts cells in each phase: Interphase 70%, Prophase 10%, Metaphase 8%, Anaphase 5%, Telophase 7%. Which of the following best explains why the largest proportion of cells are observed in interphase?

A researcher treats a mammalian cell culture with a phosphatase inhibitor. Phosphatases are enzymes that remove phosphate groups from signaling proteins, terminating their activity. Which of the following best describes the expected effect on intracellular signal transduction?

A cross between a true-breeding red-flowered plant (R¹R¹) and a true-breeding white-flowered plant (R²R²) produces all pink-flowered offspring (R¹R²). Which of the following best describes this pattern of inheritance?

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Practice Test for AP Biology - 2 Grade 10 MCQs & solutions - Free

MCQ Practice Test & Solutions: Practice Test for AP Biology - 2 (60 Questions)

Water molecules are attracted to the cellulose molecules lining the walls of xylem vessels in plants, allowing water to move upward against gravity. Which property of water best explains this interaction?

A researcher adds a molecule structurally similar to an enzyme's natural substrate to a reaction mixture. The researcher observes that increasing substrate concentration progressively restores the reaction rate until it reaches normal Vmax. Which type of inhibition is demonstrated?

A protein enzyme completely loses its ability to catalyze its target reaction after being heated to 90°C. Biochemical analysis confirms that the primary structure (amino acid sequence) is intact. Which of the following best explains why the enzyme can no longer function?

A graph plots the rate of an enzyme-catalyzed reaction (y-axis) versus substrate concentration (x-axis). The curve rises steeply at low substrate concentrations and then levels off into a plateau at high substrate concentrations. What does the plateau represent?

Phospholipids spontaneously form bilayers in aqueous environments, with hydrophobic fatty acid tails oriented inward and hydrophilic phosphate head groups facing the aqueous environment. Which of the following best explains why the nonpolar tails are excluded from contact with water?

A red blood cell is placed into a solution with a higher solute concentration than the cell's cytoplasm. Water exits the cell by osmosis, causing the cell to shrink (crenation). The solution surrounding the cell is best described as:

A researcher models cells as perfect cubes and calculates the surface area-to-volume (SA:V) ratio for cubes with side lengths of 1 cm, 2 cm, and 4 cm. The calculated SA:V ratios are 6, 3, and 1.5, respectively. Which of the following conclusions is best supported by this data?

Which of the following observations provides the strongest evidence for the endosymbiotic origin of mitochondria from an ancestral proteobacterium?

The sodium-potassium (Na+/K+) pump actively transports 3 Na+ out of and 2 K+ into the cell per ATP molecule hydrolyzed, maintaining the electrochemical gradient across the plasma membrane. If a toxin severely inhibits ATP production in the cell, which of the following consequences is most likely?

Both a eukaryotic cell and a bacterial cell need to rapidly increase production of a specific protein in response to an extracellular signal. Which of the following correctly identifies a key mechanistic difference between these two cell types in accomplishing this?

A secretory cell synthesizes digestive enzymes, packages them into membrane-bound vesicles in the Golgi apparatus, and then releases them into the extracellular space when the vesicle fuses with the plasma membrane. This process is correctly classified as:

A student claims that the Calvin cycle directly uses light energy absorbed by chlorophyll to reduce CO2 and produce G3P. Which of the following correctly evaluates this claim?

During intense anaerobic exercise, human skeletal muscle cells convert pyruvate to lactate using NADH. Which of the following best explains the primary function of this conversion?

A student states: “Both photosynthesis and cellular respiration produce carbon dioxide as a metabolic byproduct.” Which of the following correctly evaluates this statement?

A researcher isolates chloroplast stroma and maintains CO2 availability but eliminates the supply of both ATP and NADPH to the preparation. Which of the following best predicts the effect on the Calvin cycle?

Which of the following correctly distinguishes substrate-level phosphorylation from oxidative phosphorylation in cellular respiration?

A researcher radioactively labels the two carbon atoms in a single acetyl-CoA molecule entering one turn of the Krebs cycle. After one complete turn, which of the following most accurately describes the fate of those labeled carbon atoms?

During meiosis I, homologous chromosomes physically exchange corresponding segments through a process called crossing over. Which of the following best explains how crossing over contributes to genetic diversity in a population?

A cancer cell secretes a signaling molecule that binds to receptors on its own plasma membrane, stimulating the cell's own proliferation. This type of cell signaling is best classified as:

During normal limb development in vertebrates, cells in the interdigital webbing are eliminated by programmed cell death (apoptosis), forming distinct digits. A mutation that prevents caspase activation in the interdigital cells would most likely result in which of the following?

A researcher examines a rapidly dividing tissue sample under a microscope and counts cells in each phase: Interphase 70%, Prophase 10%, Metaphase 8%, Anaphase 5%, Telophase 7%. Which of the following best explains why the largest proportion of cells are observed in interphase?

A researcher treats a mammalian cell culture with a phosphatase inhibitor. Phosphatases are enzymes that remove phosphate groups from signaling proteins, terminating their activity. Which of the following best describes the expected effect on intracellular signal transduction?

A cross between a true-breeding red-flowered plant (R1R1) and a true-breeding white-flowered plant (R2R2) produces all pink-flowered offspring (R1R2). Which of the following best describes this pattern of inheritance?

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A researcher adds a molecule structurally similar to an enzyme's natural substrate to a reaction mixture. The researcher observes that increasing substrate concentration progressively restores the reaction rate until it reaches normal V_max. Which type of inhibition is demonstrated?

A student claims that the Calvin cycle directly uses light energy absorbed by chlorophyll to reduce CO₂ and produce G3P. Which of the following correctly evaluates this claim?

A researcher isolates chloroplast stroma and maintains CO₂ availability but eliminates the supply of both ATP and NADPH to the preparation. Which of the following best predicts the effect on the Calvin cycle?

A cross between a true-breeding red-flowered plant (R¹R¹) and a true-breeding white-flowered plant (R²R²) produces all pink-flowered offspring (R¹R²). Which of the following best describes this pattern of inheritance?