Practice Test 2 - High School Biology

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

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1. Skin cells form tight layers that protect the body, while nerve cells have long extensions that help transmit signals. Both cell types still contain the same complete set of genes. Which statement best connects cell structure to differentiation?
2. Emperor penguins in Antarctica often huddle tightly during winter storms and rotate positions so different individuals spend time on the colder outside. What advantage of group living does this demonstrate?
3. Scientists discovered a fossil called Tiktaalik that has fish traits (scales and gills) and tetrapod traits (a neck and wrist-like bones in its fins). Which statement best explains how this fossil supports common ancestry?
4. A trait is controlled by a single gene where $C$ is dominant over $c$. A cross produces an offspring genotype ratio of $1\,CC : 2\,Cc : 1\,cc$ (the typical result of $Cc \times Cc$). What is the probability an offspring will have genotype $Cc$?
5. In winter, some insects (and other small animals) cluster together in sheltered spaces. Compared with staying separated, what is a direct advantage of clustering?
6. In DNA, adenine (A) pairs with thymine (T). If a base on one strand is guanine (G), which base must be across from it on the other strand?
7. Claim: Group living improves survival. A student gives these pieces of evidence about a lizard species: 1) In one week, the student saw 4 lizards in a group escape a hawk attack. 2) In a 6-month study (n = 200), group-living lizards had 74% survival and solitary lizards had 71% survival in the same habitat. 3) Group-living lizards spent more time basking in the sun than solitary lizards. Which piece of evidence is least supportive of the claim?
8. In the DNA double helix, where are the sugar-phosphate backbones located?​
9. A population of rabbits has two fur color morphs. A survey counted: Brown: 36 rabbits White: 14 rabbits Which conclusion best describes the variation in fur color?
10. A model includes a box labeled "Photosynthesis (in chloroplast)" with these arrows: Inputs: CO₂ + H₂O + light energy → [Photosynthesis] Outputs: glucose (chemical energy stored) + O₂ Based on this model, which output is identified as the main energy-storage product?
11. A graph of population size (y-axis) vs. time (x-axis) shows a smooth S-shaped curve. Early on, the curve is gentle; later it becomes steep; near the end it flattens. As the population approaches carrying capacity ($K$), what happens to the population growth rate?
12. A student traces energy in the model from the Sun to cellular work. Which sequence correctly follows the model's energy pathway and energy forms?​
13. A student is modeling translation with paper pieces labeled mRNA, ribosome, tRNA, and amino acids. Which model action best represents how the correct amino acid is chosen at each step?
14. Two species have very similar DNA sequences for many genes, but they live on different continents and have different diets. Which statement best explains why DNA similarity is still evidence for common ancestry?
15. A student says, "Oxygen is the molecule that provides the energy for making ATP during cellular respiration." Which choice best corrects the student's idea?
16. A rabbit population shows heritable variation in fur thickness (thin vs. thick). A colder climate arrives, and rabbits with thicker fur survive winter more often and produce more offspring. Which observation would be the best evidence that natural selection is occurring?
17. Which sequence of events best represents the usual pathway for how a mutation can affect an organism's traits? (Assume the mutation occurs in a coding region of a gene.)
18. In a day–night model of a forest, a student wants to represent what happens over 24 hours for a tree and a deer. Which model best captures the key idea that matter cycles between photosynthesis and respiration while energy flows one-way?
19. A new highway is built through a continuous forest, leaving two smaller forest patches separated by several lanes of traffic and cleared roadside areas. Over time, a small mammal species is found only in a few isolated pockets, and individuals rarely cross the highway. Which impact is most likely from this change?
20. In a grassland food chain, energy flows: grass (producer) → rabbit (primary consumer) → fox (secondary consumer) → mountain lion (tertiary consumer). If the grass layer contains about 20,000 energy units available per year, approximately how many energy units are available to the fox level, using the 10% rule?

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