Practice Test 7 - 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 conservation team adds nesting boxes for a bird species. Before the change, nesting sites limited the population to 120 breeding pairs. After adding boxes, the number of available nesting sites increases by 50%, and nesting sites are still the limiting factor. What is the new carrying capacity (K) in breeding pairs?
2. Humans have a tailbone (coccyx) that does not form an external tail. Some other mammals have full tails used for balance or communication. Which statement best describes this as evidence for evolution?
3. DNA comparisons show that humans and chimpanzees share about 98% of their DNA sequences, while humans and mice share a lower percentage. What does this molecular evidence indicate?
4. A coastal community increases fishing pressure on a large predatory fish species. Which model best shows a plausible trophic cascade that can lead to reduced biodiversity in the coastal ecosystem?
5. A student lists three observations: (1) human embryos and chick embryos share similar early structures; (2) humans have a tailbone; and (3) humans and chimpanzees have very similar DNA sequences. Which option correctly matches each observation to a type of evidence for evolution?
6. Before factories were built, most peppered moths in a region were light-colored, and a few were dark-colored. After industrial pollution darkened tree bark, birds ate more light-colored moths. Over many generations, dark-colored moths became more common. Which choice correctly identifies the key components of natural selection shown here?
7. In the nitrogen cycle diagram, which arrow represents the process that returns nitrogen to the atmosphere as $N_2$?
8. A student says, "Crossing over makes new alleles." Which correction is most accurate? Context: Crossing over happens during meiosis when homologous chromosomes exchange segments of DNA.
9. A student says, "If two organisms have the same genotype, they will always have the same phenotype." Which example best refutes the student's claim by showing genotype–environment interaction?
10. A strawberry plant can make new plants in two ways: (1) it produces flowers that form seeds after pollen and egg cells join, and (2) it grows runners that produce new plants directly from the parent plant. Which statement correctly compares these two methods?​
11. A river is dammed to provide electricity and water storage. After the dam is built, salmon can no longer reach upstream spawning grounds, and their population declines. Which is the most direct ecological consequence of the dam in this scenario?
12. A diagram of a leaf shows carbon dioxide ($CO_2$) entering through stomata and oxygen ($O_2$) leaving through stomata. Which statement best matches the overall photosynthesis equation?
13. A fish eats algae in a pond. Later, the fish releases waste, and eventually decomposers break down that waste. What is the best description of what happens to the matter from the algae?
14. A pond food chain is: phytoplankton (producer) → insect larvae (primary consumer) → bluegill (secondary consumer) → bass (tertiary consumer). If insect larvae have about 3,000 energy units available, about how much energy is available to the bass using the 10% rule?
15. A neuron (nerve cell) has a cell body and long extensions that help transmit signals. A single neuron is best classified at which level of biological organization?
16. In a microscope image, all chromosomes are lined up along the middle of the cell in a single plane (the cell's equator). Sister chromatids are still joined at their centromeres. Which stage is this?
17. A sudden blizzard hits a region and kills many individuals in a population of small mammals. The blizzard kills animals in both dense colonies and scattered groups. Which statement best describes the blizzard as a limiting factor?
18. A student grows two cloned corn plants (same genotype). Plant A receives nitrogen-rich fertilizer and grows to 160 cm. Plant B receives no fertilizer and grows to 95 cm. Which conclusion best describes the role of environment in this result?
19. Two human siblings (not identical twins) have the same parents but look different and have different combinations of traits. Which set of processes best explains why siblings are genetically different from each other?
20. A growing plant cell must stay rigid so the stem can remain upright. The cell links many glucose molecules together to make cellulose, which is added to the cell wall. How does cellulose synthesis support the plant's function?

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