Practice Test 6 - High School Biology

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

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1. In a meadow ecosystem, sunlight shines on grass. A simple food chain is: Grass → Rabbit → Fox → Decomposers (fungi and bacteria). Which statement best explains why the grass (producer) is essential to this ecosystem's energy flow?
2. In rock layers, older layers contain fish fossils only. In slightly younger layers, a fossil like Tiktaalik appears with both fish-like traits (fins, scales) and tetrapod-like traits (a neck and sturdy limb bones). Younger layers contain early amphibian fossils. Which interpretation best matches this evidence?
3. In a forest food web, a deer (primary consumer) eats plants but does not eat all parts (e.g., roots and woody stems). Even of the plant material it eats, some energy leaves the deer as waste, and much is used for movement and maintaining body temperature. Which choice best describes what happens to the energy that does NOT get transferred to the next trophic level?
4. Hydrangea bushes with the same genotype are planted in two different gardens. In Garden 1 (acidic soil, pH 5.5) the flowers are blue. In Garden 2 (alkaline soil, pH 7.5) the flowers are pink. Which option best explains the flower-color difference?
5. A person's body temperature set point is about 37.0°C. On a hot day, their temperature rises to 39.0°C. Thermoreceptors detect the larger-than-normal increase and the body responds with heavy sweating and strong skin vasodilation. As temperature falls to 37.3°C, sweating becomes lighter. Which analysis best explains why the response is stronger at 39.0°C than at 37.3°C?
6. A student claims: "Energy cycles through ecosystems the same way matter does, so energy lost at one trophic level returns to producers." Which statement best corrects the student's claim?
7. A biologist graphs a rabbit population in a new field. The graph shows population size (y-axis) vs. time in years (x-axis). Curve A rises slowly at first and then becomes steeper and steeper with no leveling off (a J-shaped curve). What type of population growth does Curve A represent?
8. A herd of deer feeds in an open field. Some individuals frequently lift their heads and scan the area while others keep eating. Compared with a deer living alone, why can herd living increase feeding time for individuals?
9. A cell receives a signal to produce more of a certain protein (for example, an enzyme). To make that protein, the cell must first produce an RNA message that carries the instructions from DNA to the protein-making machinery. Which statement best connects nucleic acid synthesis to cell function?
10. In humans, how many chromosomes are found in a typical body cell, and how are they organized?
11. A pond food chain follows the 10% rule. If primary consumers have 4,500 kJ of energy, about how much energy is available to secondary consumers?
12. In pea plants, a gene for height has two alleles: $T$ (tall, dominant) and $t$ (short, recessive). A plant with genotype $Tt$ is tall. Which statement best explains the relationship between genotype and phenotype in this example?
13. In a cooperative breeding bird species, a breeding pair has chicks in a nest. Two older siblings (from a previous brood) help by bringing food to the chicks and calling loudly when a snake approaches. The helpers spend time feeding chicks instead of foraging for themselves. Which choice best identifies the cooperative behavior and its likely advantage?
14. A diagram is being designed for a classroom poster. It must include: (1) the substances CO2, H2O, O2, and glucose cycling between photosynthesis and cellular respiration, and (2) energy entering as sunlight and leaving as heat. Which poster layout best meets these requirements?
15. A fish species colonizes a new lake where most food is found near the bottom. In the original population, fin shape varies due to heritable differences: a few fish have broader fins that help them maneuver near the bottom, while most have narrow fins. After many generations, broad fins are common. Which sequence best describes how this adaptation arises through natural selection?
16. Two populations of the same plant species were measured for stem height. Population A (cm): minimum 12, maximum 42 Population B (cm): minimum 18, maximum 28 Which statement is best supported by these data?
17. A classroom model shows the DNA double helix as a twisted ladder. Which part of the model represents the information-carrying variable component of each nucleotide?
18. A non-native snake is accidentally introduced to an island where many birds nest on the ground. Over several years, multiple native bird species decline sharply, and one species disappears from the island. Which is the most likely cause of these changes?
19. Two small islands have the same species of lizard. On Island A, insects are abundant, but freshwater pools dry up for months each year; lizard numbers stay low and many eggs fail to hatch during dry months. On Island B, freshwater is available year-round, but insects are scarce; adults are thin and produce fewer eggs. Which statement best identifies the limiting factor on each island?
20. Which statement best compares energy transformations in photosynthesis and cellular respiration? Photosynthesis: $6CO_2 + 6H_2O + \text{light} \rightarrow C_6H_{12}O_6 + 6O_2$ Respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$

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