Practice Test 66 - 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 simplified quantitative model shows: 100 units light energy from Sun → chloroplast/photosynthesis → 4 units chemical energy stored in glucose + 96 units released as heat What does this model most directly show about photosynthesis?
2. A plant makes carbohydrates, proteins, and nucleic acids. Which matching of macromolecule to required elements and likely environmental sources is most accurate?
3. In translation, mRNA codons are read in sets of three bases. What is the relationship between an mRNA codon and the protein being built?
4. A student claims: "Consumers don't really depend on producers because carnivores eat other animals, not plants." Which response best corrects the student using energy flow in food chains?
5. The balanced photosynthesis equation is $6CO_2 + 6H_2O +$ light energy $\rightarrow C_6H_{12}O_6 + 6O_2$. According to this equation, how many $CO_2$ molecules are needed to produce 1 glucose molecule?
6. A glucose-regulating system normally keeps blood glucose near 90 mg/dL. After a meal, glucose rises. The pancreas detects the rise and releases insulin, and glucose returns toward normal. In one person, blood glucose rises to 180 mg/dL after meals and stays high for hours because insulin is not released. Which statement best analyzes what is happening to homeostasis in this case?
7. A mining operation leaves piles of waste rock near a stream. After storms, muddy water and metal-rich runoff enter the stream, and fewer aquatic insects and fish are found downstream. Which is the most likely ecosystem impact?
8. An ecosystem contains producers (plants), herbivores, carnivores, omnivores, and decomposers. Which statement correctly describes how an omnivore fits into energy flow compared with other consumers?
9. A population graph shows a J-shaped curve: it starts slowly and then rises more and more steeply over time (x-axis = time; y-axis = population size). Which interpretation best matches this pattern?
10. A fertilized egg (zygote) divides many times, producing many cells with the same DNA. Over time, these cells become specialized types such as skin cells, muscle cells, and blood cells. Which statement best summarizes how this change happens?
11. A student claims, "Natural selection creates helpful traits when the environment changes." Which option best corrects this claim while still explaining how adaptations arise?
12. A population is graphed over time with an S-shaped (logistic) curve. Growth starts slowly, becomes steepest in the middle of the graph, then flattens as it approaches carrying capacity $K$. During which part of the curve is the population growth rate fastest?
13. A cell is assembling a macromolecule by repeatedly joining small building blocks. Which option best describes polymer formation from monomers in general (including glucose → polysaccharides)?​
14. Bone marrow contains stem cells that can become red blood cells (oxygen transport), white blood cells (immune defense), or platelets (blood clotting). All of these cells come from the same stem cell and have the same DNA. Which statement best describes cell differentiation in this example?
15. A grassland reserve is created to protect a threatened bird that nests on the ground. The reserve successfully prevents development, but the bird population continues to decline because pesticides from nearby farms drift into the reserve and reduce insect prey. Which conclusion best evaluates the reserve's effectiveness and limitation?
16. In a fish population, there is heritable variation in body shape. In fast-moving water, fish with more streamlined bodies swim more efficiently and tend to produce more offspring. In still water, the same streamlined shape provides little advantage. Which statement best describes what natural selection predicts?
17. A student observes a dividing cell where sister chromatids have separated and are moving toward opposite ends of the cell. Which stage is being observed?
18. A forest ecosystem follows the 10% rule. If producers have 50,000 kJ, how much energy is available to secondary consumers (two transfers: producers → 1° → 2°)?
19. Which statement correctly describes the relationship among DNA, genes, and chromosomes in humans?
20. Two islands have the same bird species that eats seeds. On Island High-Diversity, there are many seed-producing plant species that fruit at different times. On Island Low-Diversity, most seeds come from one plant species that produces seeds only in a short season. How does plant biodiversity most likely affect the bird population dynamics across the year?

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