Practice Test 15 - 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 an arctic fox population, fur color varies and is heritable. A few foxes are born with very white winter fur, while many have darker winter fur. In a snowy habitat, predators more easily spot darker foxes. After many generations in this snowy environment, most foxes have white winter fur. Which statement best explains this adaptation through natural selection?
2. Which sequence correctly shows the basic levels of DNA packaging from smallest to most condensed form in a eukaryotic cell?
3. In DNA, which part of a nucleotide carries the information that varies from one nucleotide to another?
4. A population of lizards has a gene with two alleles: $H$ (heat-tolerance) and $h$. A heat wave began after Generation 10. Allele frequencies were measured: Generation 0: $f(H)=0.11$ Generation 5: $f(H)=0.10$ Generation 10: $f(H)=0.12$ Generation 15: $f(H)=0.28$ Generation 20: $f(H)=0.49$ Generation 25: $f(H)=0.67$ Which statement is best supported by the data?
5. In a grassland ecosystem, producers store about 60,000 kJ of energy. Using the 10% rule, how much energy is available to primary consumers?
6. Which stage of mitosis is characterized by chromosomes condensing (becoming visible) and the nuclear envelope breaking down?
7. After eating a meal, nutrients from digested food need to reach cells throughout the body. How do the digestive and circulatory systems interact to accomplish this?​
8. During a 2-minute sprint, a student's breathing rate and heart rate increase, and their leg muscles feel tired. Which flowchart best models how respiratory, circulatory, and muscular systems interact to support the sprint? (Arrows should show direction of material flow.)
9. Male peacocks vary in tail size and brightness. In one population, males with larger, brighter tails averaged about 3 mates per breeding season, while males with smaller, duller tails averaged about 1 mate per season. Which statement best links this tail trait to fitness?
10. Mechanism A: When a variable increases above normal, the body triggers responses that decrease it back toward normal. Mechanism B: When a variable increases, the body triggers responses that increase it even more until a specific endpoint is reached. Which pairing correctly identifies Mechanism A and Mechanism B?
11. A sealed container has a plant and a small animal. Over time, the animal uses $O_2$ and releases $CO_2$ during cellular respiration. Which statement best explains how the plant can help maintain the gas balance when light is available?
12. Two hydrangea bushes are cuttings from the same parent plant (so they have the same genotype). One is grown in acidic soil (pH 5.5) and produces blue flowers; the other is grown in alkaline soil (pH 7.5) and produces pink flowers. What does this demonstrate?
13. Two separate populations of the same bacterial species were monitored for the frequency of an antibiotic-resistance trait. Population 1 was repeatedly exposed to the antibiotic; Population 2 was not. Population 1 (exposed): Week 0: 2% resistant Week 2: 12% resistant Week 4: 35% resistant Week 6: 58% resistant Week 8: 74% resistant Population 2 (not exposed): Week 0: 2% resistant Week 2: 3% resistant Week 4: 2% resistant Week 6: 3% resistant Week 8: 2% resistant Which statement best matches the evidence?
14. Two siblings (not identical twins) have the same parents but are genetically different. Which explanation best accounts for this difference based on meiosis?
15. A cargo ship accidentally introduces a non-native mussel species into a large freshwater lake. The mussels reproduce rapidly and outcompete native filter-feeders for food and space. Over time, native mussel populations decline sharply. Which human impact is best illustrated by this scenario?
16. A marine food chain follows the 10% rule. Energy available at primary consumers is 9,000 kcal. Energy available at secondary consumers is 900 kcal. How much energy is lost between these two levels?
17. Claim: A population of wildflowers evolved to flower earlier in the spring after a decade of warmer temperatures. Evidence to evaluate: 1) In 2012, the average first-flowering date was day 140 of the year; in 2022, it was day 118. 2) Seeds collected in 2012 and 2022 were grown together in the same greenhouse conditions; plants from 2022 seeds flowered 10 days earlier on average than plants from 2012 seeds. 3) A botanist observed that one plant in 2022 flowered extremely early (day 90). 4) In 2022, the population size was larger than in 2012. Which choice best evaluates whether the evidence supports the claim of evolution (population-level genetic change)?
18. Consider this change in a DNA segment: Original: ATGCCGTT; Changed: ATGCTGTT. The two sequences differ by one base. Conceptually, why might this single change matter?
19. A set of fossils is found in a rock sequence where deeper layers are older. In older layers, a lineage has small hind limbs; in younger layers, hind limbs are reduced; and in the youngest layers, only tiny pelvic bones remain. Modern descendants in this lineage lack external hind limbs. Which explanation best connects this fossil pattern to evolution?
20. A graph shows population size (y-axis) vs. time (x-axis) for two species in the same habitat. Curve A is S-shaped and levels off. Curve B is J-shaped and continues to rise more steeply. Which statement correctly compares the two curves?

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