Practice Test 74 - High School Biology

20 questions. Answer them in any order, then submit to see your score and every explanation.

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1. In many organisms, cellular respiration captures only about 40% of the energy from glucose in ATP, and the rest is released as heat. Which observation is best explained by this heat release?
2. In a population of mice, fur color can be light or dark. Researchers tracked the percentage of dark mice over 8 generations after the habitat became darker due to a wildfire. Generation 0: 12% dark Generation 1: 18% dark Generation 2: 26% dark Generation 3: 37% dark Generation 4: 49% dark Generation 5: 60% dark Generation 6: 69% dark Generation 7: 75% dark Generation 8: 79% dark Which explanation best fits the trend?
3. A bird species nests only in large, old trees with sturdy branches. In one park, there are about 45 suitable trees. Each breeding pair needs one suitable tree to build a nest. Even in years when insects (food) are abundant, the number of breeding pairs stays close to 45. Which factor is limiting the number of breeding pairs in this park?
4. A gene in a fish population has two alleles, $A$ and $a$. Scientists measured allele frequencies over time. Generation: 0 | 5 | 10 | 15 | 20 $f(A)$: 0.80 | 0.70 | 0.60 | 0.52 | 0.45 $f(a)$: 0.20 | 0.30 | 0.40 | 0.48 | 0.55 Which statement best describes what is happening in this population?
5. Claim: A fish population in a polluted river evolved tolerance to a toxic chemical. Evidence: 1) In 2000, 20% of fish survived 24 hours in water containing the toxin; in 2020, 78% survived the same test. 2) Fish from 2020 and 2000 were both raised for one generation in clean water; offspring of 2020 fish still showed higher survival in toxin tests. 3) The river's fish population size increased from 10,000 to 50,000 between 2000 and 2020. 4) In 2020, one fish survived an extremely high toxin dose. Which evidence is most relevant for showing population-level evolution (not just population growth or individual survival)?
6. When a person stands up quickly, gravity causes blood to pool in the legs, and blood pressure at the brain briefly drops. Pressure receptors in major arteries detect the drop and signal the heart to beat faster and blood vessels to constrict. These responses raise blood pressure back toward normal within seconds. Once blood pressure is near normal, the signals decrease. If the pressure receptors did NOT detect the drop in blood pressure, what would most likely happen next?
7. A bacterial disease spreads through a colony of prairie dogs. When the colony is small and individuals live far apart, only a few prairie dogs get sick. As the colony grows and burrows become crowded, the disease spreads rapidly and many prairie dogs die. This pattern best describes the disease as which type of limiting factor?
8. In a bird colony nesting on a cliff, when a hawk approaches one nest, many adult birds fly toward the hawk and dive-bomb it until it leaves the area. What is the best description of the cooperative benefit of this behavior?
9. Two species have similar-looking body shapes due to living in similar environments, but their DNA sequences are much less similar than expected if they were close relatives. Which statement best explains how molecular evidence helps in this situation?
10. A student observes that two genetically identical seedlings (same genotype) grow to different sizes when one is grown in nutrient-rich soil and the other in nutrient-poor soil. Which statement best distinguishes genotype from environment in this scenario?
11. A fox in a diverse grassland eats rabbits, voles, insects, and ground-nesting birds. In a simplified habitat nearby, a predator relies mostly on rabbits. One year, a disease causes the rabbit population to drop sharply. How does food web diversity affect predator population dynamics in these two habitats?
12. In many organisms, only about 40% of the chemical energy in glucose ends up stored in ATP during cellular respiration, and the rest is released as heat. Which observation is best explained by this heat release?
13. A diploid cell (2n) undergoes meiosis in the testes to form sperm. Which outcome is expected at the end of meiosis?
14. A disease outbreak reduced sea star populations on a rocky shoreline in Year 0. Sea stars are predators of mussels. Scientists counted sea stars and measured percent cover of mussels. Data: - Pre-outbreak (Year -1): sea stars = 38; mussel cover = 35% - Year 0: sea stars = 3; mussel cover = 62% - Year 2: sea stars = 10; mussel cover = 55% - Year 5: sea stars = 26; mussel cover = 41% Which evidence most directly indicates recovery of the predator population and a return toward the earlier community balance?
15. A student says, "Any mutation in DNA will definitely change the protein and cause a disease." Which statement best corrects this idea while keeping the DNA → protein connection accurate?
16. A student builds a DNA model using repeating units. Each unit includes a sugar, a phosphate group, and one base labeled A, T, G, or C. Which set of parts correctly describes the components of a single DNA nucleotide?
17. In a population of beetles, color is controlled by one gene with two alleles: $G$ and $g$. After a drought, survival probabilities differ by genotype: $GG$: 80% survive, $Gg$: 70% survive, $gg$: 20% survive. Assuming survivors reproduce, which allele is expected to increase in frequency in the next generation?
18. In an energy pyramid, producers contain 60,000 kJ of energy. Using the 10% rule, approximately how much energy is available to primary consumers?
19. During the day, a plant in a meadow does photosynthesis and cellular respiration. At night, it does only cellular respiration. Which model best captures how matter (CO2, H2O, O2, glucose) cycles between photosynthesis and respiration over a 24-hour period, while energy flows one-way?
20. What is the main function of tRNA during translation?

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