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Practice Test 62 - High School Biology

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

  1. A student draws this (incorrect) energy model: Glucose → chlorophyll → light energy → Sun Which change would best correct the model to match energy flow in photosynthesis?
  2. A grassland site burned in a wildfire (Year 0). Ecologists tracked plant species richness and aboveground plant biomass (a productivity indicator). Which statement best interprets the recovery trajectory? Time since fire (years): Pre-fire, 0, 1, 3, 6 Plant species richness (# species): 42, 11, 24, 35, 40 Biomass (g/m2^2): 510, 90, 260, 430, 500
  3. A coral reef experienced a severe heatwave (bleaching event) in Year 0. Scientists tracked live coral cover and algae cover. Which conclusion best describes recovery completeness by Year 8? Percent cover: - Pre-heatwave: coral 52%, algae 18% - Year 0: coral 12%, algae 55% - Year 2: coral 15%, algae 50% - Year 5: coral 20%, algae 45% - Year 8: coral 22%, algae 43%
  4. A lake experienced an oil spill (Year 0). Cleanup removed most oil within 2 months. Scientists measured water clarity (Secchi depth, m) and phytoplankton productivity (mg C/L/day). Data: - Pre-spill: Clarity = 3.6 m; Productivity = 4.8 - Year 0 (2 weeks after spill): Clarity = 0.9 m; Productivity = 1.2 - Year 1: Clarity = 2.4 m; Productivity = 3.1 - Year 3: Clarity = 3.3 m; Productivity = 4.2 - Year 7: Clarity = 3.5 m; Productivity = 4.7 Approximately how long did it take for both indicators to return close to pre-spill levels (near-complete recovery)?​
  5. Why can the digestive system not, by itself, ensure that all body cells receive glucose from a meal?
  6. A cell membrane is damaged by heat and must be repaired to keep the cell's internal environment stable. Which macromolecule synthesis most directly supports restoring the cell boundary?
  7. An energy pyramid follows the 10% rule: Producers = 80,000 kcal, Primary consumers = 8,000 kcal, Secondary consumers = 800 kcal, Tertiary consumers = ?. What is the energy available to tertiary consumers?
  8. A class models an ecosystem with this diagram: Sun → producers (plants) → primary consumers (herbivores) → secondary consumers (carnivores) → tertiary consumers (top predators). Decomposers break down dead organisms from every level and return nutrients to the soil. Which statement best describes how matter and energy move in this model?
  9. A non-native snake species is accidentally introduced to an island where many birds nest on the ground. Within decades, several native bird species decline sharply. Which is the most likely cause of this decline?
  10. During a run, a student notices they are breathing faster and their heart is beating faster. How do the respiratory and circulatory systems work together to help the student's leg muscles keep working during the run?
  11. A student says, "This forest is stable because nothing ever changes there." Which correction best matches the scientific meaning of ecosystem stability?
  12. A forest food chain is: Oak tree (leaves) → Caterpillar → Bird → Hawk. Which statement correctly compares the caterpillar and the bird in terms of consumer type?
  13. A farmer begins using a new pesticide in Year 1. The percentage of insects in the field that survive a standard pesticide-dose test is recorded each year. Year 0: 3% survive Year 1: 4% survive Year 3: 18% survive Year 5: 52% survive Year 8: 81% survive Which conclusion is best supported by the pattern in the data?
  14. A population of insects has genotypes BBBB, BbBb, and bbbb for a gene affecting toxin resistance. In an environment with the toxin, survival probabilities are: BBBB: 85%, BbBb: 40%, bbbb: 10%. Which statement best predicts what happens to allele BB?
  15. A scientist labels carbon atoms in CO2 with a tracer and later finds the tracer in cellulose in a plant cell wall. What is the best explanation for how the labeled carbon atoms ended up in cellulose?
  16. A forest was selectively logged in Year 0. Ecologists compared the logged site to an unlogged site by measuring tree species richness and canopy cover (%). Year 0 (1 year after logging): - Logged: richness 9; canopy 22% - Unlogged: richness 28; canopy 86% Year 15: - Logged: richness 21; canopy 63% - Unlogged: richness 27; canopy 84% Which conclusion best matches the evidence about the logged site by Year 15?
  17. A student holds their breath underwater. After a short time, they must surface to breathe. Which explanation best describes how the respiratory and circulatory systems normally interact to prevent this problem?
  18. During transcription (the first step of gene expression), a cell makes a temporary mRNA copy of a gene. In the nucleus, the DNA double helix opens in the gene region, one DNA strand acts as the template, RNA nucleotides base-pair to it (A pairs with U in RNA), and RNA polymerase links the RNA nucleotides into a single-stranded mRNA that then separates and leaves the DNA unchanged. If the DNA template strand sequence is TACGAT, what mRNA sequence is produced?
  19. How many chromosomes are found in a typical human body cell (somatic cell)?
  20. A student says: "During transcription, the cell makes an RNA strand that is an exact copy of the DNA template, including using T." Which correction best fixes the student's mistake?

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