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Practice Test 43 - High School Biology

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

  1. A student says, "Homeostasis means the body never changes internally." Using the idea of set points and feedback, which statement best corrects the student's misunderstanding?
  2. In snakes, some species have tiny internal bones that resemble the pelvis and hind limb bones of other reptiles, even though these snakes do not have functional legs. This is best interpreted as which evidence for evolution?
  3. Claim: A weed population evolved herbicide resistance due to repeated herbicide use. Study results: - Field 1 (sprayed every year): percent of plants surviving the labeled herbicide dose rose from 4% in 2010 to 65% in 2020. - Field 2 (never sprayed; nearby): percent surviving stayed about 5% from 2010 to 2020. - A gardener reports that one large weed plant became "used to" the herbicide after being sprayed multiple times. - Soil nutrients increased in Field 1 between 2010 and 2020. Which evaluation is most accurate?
  4. A population starts with two genotypes for a disease-resistance gene: resistant (RRRR or RrRr) and non-resistant (rrrr). During an outbreak, 90% of resistant individuals survive, but only 40% of non-resistant individuals survive. Without doing exact calculations, what is the most reasonable prediction about the RR allele frequency in the next generation?
  5. A rabbit population in a grassland has abundant grass and plenty of burrows. When foxes move into the area, rabbit numbers stop increasing and then remain relatively stable for several years. No major droughts occur during this time. Which factor is most likely limiting the rabbit population size?
  6. During transcription, the mRNA produced is complementary to the DNA template strand (A-U, T-A, G-C, C-G). If the DNA template strand reads ATGC, what is the mRNA sequence made?
  7. A fish population contains heritable variation in tolerance to warm water. A power plant warms a section of the river, raising average water temperature for many years. After many generations, more fish in that section can tolerate higher temperatures. Which statement best explains why the population changed?
  8. A wildlife reserve estimates it can provide enough food for 1,000 deer, enough water for 1,200 deer, and enough winter shelter for only 600 deer. Assuming deer must have all three resources to survive long-term, what is the carrying capacity (K) for deer in this reserve?
  9. Humans have 46 chromosomes in most body cells. Which statement best explains why the chromosome number is usually constant within a species?
  10. In snapdragons, flower color shows incomplete dominance: RR = red, WW = white, and RW = pink. A pink plant is crossed with another pink plant (RW × RW). Which offspring phenotype ratio is expected?
  11. A plant is placed in a dark closet but still has water in the soil and carbon dioxide in the air. Based on the overall photosynthesis equation, what will happen to photosynthesis?
  12. A food chain is: grass (producers) → grasshopper (primary consumer) → frog (secondary consumer) → snake (tertiary consumer). If the grass level contains about 12,000 kcal of energy stored in biomass, about how much energy would be stored in the snake level using the 10% rule?
  13. A hydrangea bush with a particular genotype produces blue flowers when grown in acidic soil (pH 5.5) and pink flowers when grown in alkaline soil (pH 7.5). If cuttings from the same bush are planted in both soils, what best explains the different flower colors?
  14. Just as the words CAT and TAC have different meanings because the letters are in a different order, DNA sequences can encode different information based on base order. Which statement best explains why base order matters in DNA?
  15. An ant scout finds a large piece of food and lays a pheromone trail back to the nest. Soon many ants follow the trail, and several ants work together to carry the food item, which is too heavy for one ant to move. Which statement best describes the cooperative benefit in this example?
  16. A grassland food chain is: grass → grasshopper → frog → snake. Which statement best describes what happens to the matter (atoms) in the grass as it moves through this chain?
  17. An endangered frog has fewer than 60 adults left in the wild. The main problems are (1) loss of breeding ponds due to drainage and (2) a fungal disease that spreads easily in disturbed habitats. A plan proposes: captive breeding to increase numbers, restoring several ponds, and then reintroducing frogs. Which evaluation is most scientifically sound?
  18. In a giraffe population, neck length varies and is heritable. During dry seasons, leaves are scarce near the ground but still available higher in trees. Giraffes with slightly longer necks get more food and leave more offspring. Over many generations, the average neck length increases. Which statement best describes why long necks are considered an adaptation?
  19. Two rivers experience the same chemical spill. River A shows a small drop in insect populations and stays close to normal during the spill. River B's insect populations crash during the spill but return to near normal within a year. Which choice correctly identifies resistance and resilience in this situation?
  20. Why can the digestive system not, by itself, ensure that nutrients from food reach every cell in the body?​

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