Practice Test 50 - 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 plant trait (waxy leaves) helps reduce water loss. In a drought year, plants with waxy leaves produce an average of 30 seeds each, while plants without waxy leaves produce an average of 10 seeds each. If conditions stay similar for multiple generations, what is the most likely change in the frequency of the waxy-leaf trait?
2. A student claims: "When a plant builds a protein, it turns glucose directly into protein without changing the arrangement of atoms." Which statement best corrects the student's claim?
3. A population of insects contains a few individuals with a heritable allele that makes them resistant to a pesticide. Farmers spray the same pesticide repeatedly for many seasons. Which change is most likely over time?
4. A plant cell has 100 carbon atoms available in glucose molecules (these carbon atoms originally came from CO2). During growth, 50 carbon atoms end up in starch, 30 carbon atoms end up in proteins, and 20 carbon atoms end up in membrane lipids. Which statement best explains what this accounting shows about synthesis?
5. A graph shows population size (y-axis) vs. time (x-axis). The population increases above a dashed horizontal line labeled $K = 1{,}000$, reaches about 1,500, and then drops quickly to around 400. Which interpretation best describes what happened?
6. A mutation changes one codon in an mRNA molecule. Which statement best explains how this could affect the protein made during translation?
7. A pond contains algae (photosynthesizers), insects that eat algae, fish that eat insects, and herons that eat fish. If all producers (algae) were suddenly removed, what is the most likely long-term outcome for the pond ecosystem?
8. A line graph (described below) shows the frequency of a virus variant (V2) in a city over time: - 2018: 5% - 2019: 7% - 2020: 9% - 2021: 48% - 2022: 86% Which interpretation best describes the trend?
9. Two genetically identical corn plants (clones) are grown from cuttings. Plant 1 is grown with regular fertilizer and reaches 160 cm. Plant 2 is grown in the same light and water conditions but without fertilizer and reaches 95 cm. What is the best conclusion about genotype and environment in this case?
10. Two prairies experience the same drought. Prairie A has many plant species, including some that tolerate dry conditions and some that tolerate wet conditions. Prairie B is dominated by one grass species. After the drought, Prairie A still has plant cover, while Prairie B has large bare patches. What best explains the difference in population stability?
11. A non-native snake is accidentally introduced to an island where many birds nest on the ground and have no evolved defenses against snake predators. Within a decade, several bird species become rare or disappear from the island. What is the most likely cause of the bird declines?
12. A graph shows population size (y-axis) vs. time (x-axis) for a species introduced to an island. The curve starts low, then rises rapidly, and finally becomes nearly horizontal around 2,000 individuals. Approximately when the curve becomes nearly horizontal, what is the best interpretation?
13. A student grows genetically identical bean plants under two light conditions. Group 1 grows under bright light and becomes green with sturdy stems. Group 2 grows in very low light and becomes tall, pale, and weak. What does this best illustrate?
14. Claim: A fish population in Lake Azul evolved to tolerate warmer water after a power plant warmed the lake. Evidence: 1) 1990: 5% of fish survived a 30°C heat-tolerance test; 2020: 60% survived the same test. 2) 2020: fish raised in a cool lab tank (not warm lake water) still showed higher survival in the 30°C test than fish from 1990 samples. 3) A biologist observed that individual fish can temporarily move to deeper, cooler water on hot days. 4) The lake's average temperature increased by 2°C between 1990 and 2020. Which evidence combination best distinguishes population evolution from individual acclimation?
15. During cellular respiration, a cell breaks down glucose ($C_6H_{12}O_6$) in the presence of oxygen to form $CO_2$ and $H_2O$. What happens to the chemical energy originally stored in glucose during this process?
16. A pancreas cell must continually produce the protein hormone insulin. How does protein synthesis connect to maintaining homeostasis in the body?
17. During a 2-minute sprint, a student's breathing rate increases and their leg muscles begin to feel tired. They keep running, and their heart rate stays high until they stop. Which flowchart model best represents how body systems interact to support the working muscles during the sprint?
18. Which option correctly describes the direction of energy flow and why energy does not "cycle" in an ecosystem?
19. A student claims that light energy is a product of photosynthesis. Based on the equation $6CO_2 + 6H_2O +$ light energy $\rightarrow C_6H_{12}O_6 + 6O_2$, which statement is correct?
20. A cell experiences damage to many of its enzymes due to heat stress. To recover, it must make new enzymes. Why is synthesizing proteins essential for the cell's metabolism?

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