Practice Test for AP Biology - 1 Grade 10 MCQs & solutions - Free

Which property of water best explains why water molecules at the surface of a liquid resist breaking apart, creating surface tension?

A researcher heats an enzyme solution to 80°C and observes a complete loss of catalytic activity. The enzyme is then cooled to its optimal temperature, but activity does not return. Which of the following best explains this observation?

A researcher tests the activity of pepsin (a stomach enzyme) at pH values of 2, 4, 7, and 9. The results show maximum activity at pH 2 and near-zero activity at pH 9. Which of the following is the most valid conclusion from this experiment?

During digestion, a polysaccharide is broken down into its individual monosaccharide subunits. Which of the following reactions is responsible for this process?

A mutation in a bacterium causes it to produce only saturated fatty acids in its membrane phospholipids. Compared to a wild-type bacterium with a mixture of saturated and unsaturated fatty acids, how would this mutation most likely affect membrane function?

A graph shows enzyme reaction rate (y-axis) versus substrate concentration (x-axis) for an enzyme under three conditions: no inhibitor, competitive inhibitor added, and non-competitive inhibitor added. Which of the following correctly describes how the maximum reaction rate (V_max) differs between the three conditions?

A cell moves potassium ions from a region of low concentration to a region of high concentration using membrane proteins. Which of the following correctly identifies this transport mechanism?

A researcher places plant cells into three solutions: distilled water, 0.9% NaCl, and 2.0% NaCl. After 30 minutes, cells in distilled water appear swollen, cells in 0.9% NaCl appear unchanged, and cells in 2.0% NaCl appear plasmolyzed. Which of the following conclusions is best supported by these results?

A researcher studying the endosymbiotic theory notes that mitochondria and chloroplasts share several features with modern prokaryotes. Which of the following observations provides the strongest evidence supporting the endosymbiotic origin of these organelles?

A student calculates the surface area-to-volume (SA:V) ratios for three cube-shaped cells: Cell 1 (side = 1 μm), Cell 2 (side = 2 μm), and Cell 3 (side = 4 μm). Which of the following correctly ranks the SA:V ratios from highest to lowest?

Cholesterol molecules are embedded within the phospholipid bilayer of animal cell membranes. At high temperatures, cholesterol reduces membrane fluidity, while at low temperatures, cholesterol prevents the membrane from solidifying. Which of the following best explains cholesterol's role in membrane function?

A scientist examines a single-celled organism and determines that it lacks a membrane-bound nucleus, has circular DNA, and possesses 70S ribosomes. Which of the following best classifies this organism?

A researcher bubbles different wavelengths of light over aquatic plants and measures the rate of oxygen gas production. The highest O₂ production rates are observed at approximately 430 nm (blue) and 680 nm (red), with minimal production at 550 nm (green). Which of the following best explains why green light produces the lowest rate of photosynthesis?

A plant cell is actively performing both photosynthesis and cellular respiration simultaneously. Under conditions of high light intensity, which of the following statements correctly describes the net movement of CO₂ and O₂ in the cell?

During cellular respiration, ATP is produced by two distinct mechanisms. Which of the following correctly distinguishes substrate-level phosphorylation from oxidative phosphorylation?

A researcher measures ethanol production in yeast cultures under varying oxygen concentrations. At 0% O₂, ethanol production is highest. As O₂ increases from 0% to 5%, ethanol production drops sharply, and above 5% O₂, ethanol production approaches zero. Which of the following best explains why ethanol production decreases as oxygen availability increases?

In hot, dry environments, C4 plants have a competitive advantage over C3 plants. A researcher compares the photosynthetic efficiency of a C3 and a C4 plant under conditions of high temperature and low humidity. Which of the following best explains the C4 plant's advantage?

A researcher adds a chemical that makes the inner mitochondrial membrane freely permeable to protons (H⁺). Which of the following best predicts the effect on ATP production?

Epinephrine binds to a G-protein coupled receptor on the surface of a liver cell. This binding activates adenylyl cyclase, which converts ATP to cAMP. The cAMP then activates protein kinase A, which phosphorylates enzymes involved in glycogen breakdown. In this pathway, cAMP is functioning as:

A researcher identifies a mutation in a gene that normally produces a protein that halts cell division when DNA damage is detected at the G2 checkpoint. The mutation causes this protein to be completely nonfunctional. Which of the following best describes the consequence of this mutation?

A researcher treats dividing cells with a drug that prevents the degradation of mitotic cyclins. Under normal conditions, cyclin levels drop sharply as cells transition from metaphase to anaphase. Which of the following best predicts the effect of this drug on cell division?

A cell undergoes a division process in which homologous chromosomes are separated into different daughter cells, resulting in daughter cells with half the original chromosome number. This process is best described as:

A cell receives a death signal through a receptor that activates a cascade of caspase enzymes, ultimately leading to DNA fragmentation and programmed cell death. A mutation in this pathway causes the caspases to remain permanently inactive. Which of the following most accurately predicts the long-term consequence of this mutation?

A researcher measures the concentration of a signaling molecule at distances of 1 mm, 10 mm, 50 mm, and 500 mm from its source cell. The molecule is only detected at biologically significant concentrations within 1–10 mm of the source. At distances greater than 50 mm, concentration falls below the detection threshold. This pattern is most consistent with which type of cell signaling?

In a cross between a red-flowered plant (R₁R₁) and a white-flowered plant (R₂R₂), all F1 offspring display pink flowers (R₁R₂). This inheritance pattern is best described as:

A researcher performs a monohybrid cross (Aa × Aa) and observes 90 dominant phenotype offspring and 30 recessive phenotype offspring out of 120 total. The expected 3:1 ratio predicts exactly 90 dominant and 30 recessive offspring. The calculated chi-square (χ²) value is 0.0. Which of the following is the correct interpretation?

A woman who is a carrier for an X-linked recessive disorder (X^AX^a) and an unaffected man (X^AY) have children. Which of the following correctly states the probability that their son will be affected by the disorder?

In pea plants, round seed shape (R) is dominant over wrinkled (r), and yellow seed color (Y) is dominant over green (y). Two plants heterozygous for both traits (RrYy × RrYy) are crossed. What fraction of the offspring is expected to be homozygous recessive for both traits (rryy)?

During meiosis I in a cell with a normal diploid number of 46 chromosomes, nondisjunction of chromosome 21 occurs. If the resulting egg cell (with an extra chromosome 21) is fertilized by a normal sperm, what is the chromosome number in the resulting zygote?

In mice, coat color is determined by two genes. Gene A (agouti, A_) produces a brown coat, but only if gene B (B_) is also present. If gene B is homozygous recessive (bb), the coat is white regardless of the gene A genotype. When AaBb mice are crossed with each other, which phenotypic ratio is expected in the offspring?