Practice Test 84 - High School Biology

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

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1. A cell has 10 chromosomes. During interphase, it replicates its DNA. After DNA replication (still in interphase), how many chromosomes and sister chromatids does the cell have?
2. A wetland can support up to 400 frogs based on insect food, up to 900 frogs based on available water, and up to 500 frogs based on space for egg-laying. If the frog population rises to 650 frogs, what is the most likely outcome over time (assuming conditions stay the same)?
3. A student wonders why a muscle cell and a nerve cell look and work differently even though they came from the same embryo and contain the same DNA. Which explanation is most accurate?
4. A student traces nitrogen in a garden ecosystem. Which pathway best represents a simplified nitrogen cycle (without requiring detailed chemistry)?
5. A diagram includes both photosynthesis and cellular respiration: Sun → light energy → Photosynthesis (in chloroplast) → glucose + O2 → Cellular respiration (in cells) → ATP + CO2 + H2O Based on the diagram, which best describes the overall energy pathway?
6. A cell stops making RNA for several hours. Soon after, the cell's production of new proteins drops sharply. Which statement best explains the synthesis-to-function connection?
7. On a beach with very light-colored sand, a population of mice includes two fur-color variants: light fur and dark fur. In a field study, birds caught about 15% of light-furred mice they attacked but about 60% of dark-furred mice they attacked. Which statement best connects fur color to fitness in this environment?
8. A cut on the skin damages a small blood vessel. Platelets stick to the damaged area and release chemicals that attract more platelets. The growing platelet plug causes even more chemical release, which attracts even more platelets, until the hole is sealed and bleeding stops. Which choice best explains why this is positive feedback?
9. A meadow has many flowering plant species and five common pollinators (bees, butterflies, beetles, flies, and hummingbirds). A nearby orchard is mostly one flowering crop and depends heavily on one pollinator species. If that pollinator species declines due to pesticide exposure, what role does biodiversity play in population stability and ecosystem function?
10. A student claims that the model shows energy cycling: "Energy goes from the Sun to the plant and then back to the Sun." Which statement best corrects the student using the model's idea of energy flow?
11. In translation, the ribosome reads mRNA in units called codons. What is a codon and how does it relate to the protein being made?
12. Complete the overall cellular respiration equation by choosing the correct set of products: $\mathrm{C_6H_{12}O_6 + 6O_2 \rightarrow \; ?}$
13. A simplified energy flow model for a grassland is shown below (numbers are energy units captured/available at each level): Sunlight → Producers (grass: 10,000) → Primary consumers (rabbits: 1,000) → Secondary consumers (hawks: 100) Heat loss arrows leave each trophic level box. Which statement best matches what the arrows show about energy in this model?
14. A researcher tracked allele $R$ (disease-resistance) in two nearby plant populations for 12 generations. Population A (near a pathogen outbreak): Gen 0: $R$ = 0.12 Gen 4: $R$ = 0.29 Gen 8: $R$ = 0.55 Gen 12: $R$ = 0.73 Population B (no outbreak): Gen 0: $R$ = 0.11 Gen 4: $R$ = 0.10 Gen 8: $R$ = 0.12 Gen 12: $R$ = 0.11 Which statement is best supported by the comparison?
15. During cellular respiration, a muscle cell breaks down glucose (C6H12O6) using oxygen and produces CO2 and H2O. What happens to the chemical energy that was stored in glucose during this process?
16. A diagram in a textbook shows: neuron → nervous tissue → brain → nervous system → human. Which level of organization is the brain in this sequence?
17. A student says, "The products of photosynthesis become the reactants of cellular respiration." Using the overall equations below, which option best supports the student's claim? Photosynthesis: $6CO_2 + 6H_2O + \text{light} \rightarrow C_6H_{12}O_6 + 6O_2$ Cellular respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$
18. Humans have 46 chromosomes in most body cells, while fruit flies have 8. What does this best illustrate?
19. A plant's root system includes roots that absorb water and minerals. A single root (made of multiple tissue types working together) is best classified as which level of organization?
20. Living in groups can increase competition for food and can make it easier for diseases to spread. Why do many animals still form herds, flocks, schools, or colonies?

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