Practice Test 77 - 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 student surveys two grassland plots for plant species. Plot 1 contains: bluestem, clover, goldenrod, milkweed, thistle, and ryegrass. Plot 2 contains: bluestem, clover, and goldenrod. What is the species richness of Plot 1?
2. A control system monitors an internal condition and responds whenever it deviates from a set point. Which scenario best demonstrates why homeostasis is considered an active process rather than a passive one?
3. In a population of giraffes, neck length varies because of heritable genetic differences. During a long drought lasting many generations, most leaves close to the ground are eaten quickly, but leaves high in trees remain available. Over many generations, the average neck length in the giraffe population increases. Which explanation best describes how this change is an adaptation produced by natural selection (not by giraffes "trying" to change)?
4. A lizard population includes two toe-pad phenotypes: large pads (helpful on smooth rocks) and small pads. Researchers tracked phenotype frequencies for 15 generations after a new smooth-rock habitat became common. Generation 1: 40% large, 60% small Generation 5: 55% large, 45% small Generation 10: 73% large, 27% small Generation 15: 81% large, 19% small Which interpretation best fits the data?
5. Which statement accurately distinguishes asexual reproduction from sexual reproduction?
6. During which stage of mitosis do sister chromatids separate and move to opposite poles of the cell?
7. A student goes for a run on a warm day. Her core body temperature rises from 37.0°C to 38.6°C. Thermoreceptors in the skin and brain detect the increase and signal effectors. She begins sweating and the blood vessels near her skin dilate, and after several minutes her temperature falls back to 37.2°C. Which option best traces how this feedback mechanism maintains internal stability?
8. A mosquito population has heritable variation: about 5% carry an allele that makes them resistant to insecticide Y. Farmers spray insecticide Y repeatedly over several years. Which outcome best illustrates natural selection?
9. For a diploid organism, which statement correctly describes genotype versus phenotype for a single-gene trait such as flower color?
10. In a population of mice, fur thickness is influenced by a gene with alleles $T$ and $t$. During a cold winter, survival probabilities are: $TT$: 80%, $Tt$: 70%, $tt$: 60%. Compared with a year with no selection (Hardy-Weinberg conditions), what is the most likely outcome over several winters like this?
11. A city wants to reduce harmful air pollution (nitrogen oxides and particulate matter) from vehicles. Two options are proposed: Option A: Expand public transit and build safe bike routes to reduce the number of car trips. Option B: Install large air-filter towers near highways to capture particles after they are emitted. Which option more directly addresses the root cause of the pollution problem, and what is a key limitation?
12. A carbon atom is in atmospheric $CO_2$ above a forest. Which pathway correctly traces a carbon cycle route that returns that same carbon atom back to the atmosphere?
13. A simplified mRNA segment is shown as codons: AUG–XXX–YYY–Stop (you do not need to know what XXX or YYY code for). Which statement best describes how this mRNA is translated?
14. Independent assortment occurs during meiosis when homologous chromosome pairs separate into different cells. What does independent assortment mean, and why does it increase variation in gametes?
15. Two islands each have lizards with a heat-tolerance allele $H$ and a low-tolerance allele $h$. On Island 1 (strong selection), survival is $HH$ = 95%, $Hh$ = 90%, $hh$ = 10%. On Island 2 (weak selection), survival is $HH$ = 95%, $Hh$ = 93%, $hh$ = 90%. Which statement best compares how fast allele frequencies are expected to change?
16. A person breathes in oxygen and later breathes out carbon dioxide. How is this related to cellular respiration in body cells?
17. A student claims: "If evolution is true, there should be fossils with mixed features between major groups." Which example best supports evolution using transitional fossils?
18. Claim: Decomposition returns phosphorus (P) to the soil, contributing to nutrient cycling. A student measured soil phosphate (PO$_4^{3-}$) near a compost pile and near a control area with no compost. Evidence: 1) Soil phosphate near compost increased from 12 ppm to 28 ppm over 6 weeks. 2) Soil phosphate in the control area stayed near 11–13 ppm over the same period. 3) The compost pile decreased in volume and became darker and crumbly. 4) The compost pile smelled strong. Which option identifies the most relevant evidence supporting the claim?
19. After a wildfire, a forest's plant cover and animal populations drop sharply. Ten years later, the forest has a similar mix of tree species and wildlife as before the fire. Which statement best describes the forest's response?
20. A DNA segment contains the bases A, T, G, and C in some order. Based on complementary base pairing, which statement must be true about the opposite strand?

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