Biology HESI A2 2024

Correct Answer: D

Rationale: The correct answer is D: genus; species. "Felis" is the genus and "catus" is the species in the scientific name Felis catus. Genus is a broader classification that includes closely related species, while species is the most specific classification level. Kingdom (choice A) is too broad, family (choice A) is at a higher level than species, order (choice B) is too specific, subspecies (choice B) is not part of the scientific name, phylum (choice C) is too broad, and class (choice C) is a higher classification level than species.

Correct Answer: C

Rationale: The correct answer is C: thymine. In DNA, adenine always pairs with thymine through two hydrogen bonds. This is a fundamental principle known as Chargaff's rule, where A pairs with T and C pairs with G. Thymine is a pyrimidine base, complementing adenine, which is a purine base. Therefore, thymine is the most suitable choice for adenine in a DNA strand. Choices A, B, and D are incorrect because adenine does not pair with cytosine (A), uracil (B), or guanine (D) in DNA.

Correct Answer: C

Rationale: The formula represents the process of photosynthesis where carbon dioxide (CO₂) and water (H₂O) are converted into glucose (C₆H₁₂O₆) and oxygen (O₂) in the presence of sunlight. Step 1: 6CO₂ + 6H₂O represent the reactants involved in photosynthesis. Step 2: C₆H₁₂O₆ + 6O₂ represent the products formed during photosynthesis. Therefore, the correct answer is C: Photosynthesis. Other choices are incorrect because: A: Glycolysis involves the breakdown of glucose into pyruvate. B: Cellular respiration involves the breakdown of glucose to produce energy. D: Electronic transport is related to the movement of electrons in cellular respiration, not photosynthesis.

Correct Answer: C

Rationale: The correct answer is C: Producers > secondary consumers. This is true because producers, like plants, have the highest energy content in an ecosystem as they convert sunlight into energy through photosynthesis. Secondary consumers, such as carnivores, obtain energy by consuming primary consumers or other secondary consumers, resulting in a lower energy content compared to producers. A: Decomposers < secondary consumers - Incorrect. Decomposers break down organic matter, releasing nutrients, and have a lower energy content compared to secondary consumers. B: Primary consumers < producers - Incorrect. Primary consumers, like herbivores, consume producers directly, so they have a lower energy content than producers. D: Secondary consumers < primary consumers - Incorrect. Secondary consumers typically have a lower energy content than primary consumers as they obtain energy by consuming them.

Correct Answer: B

Rationale: The correct answer is B because it involves a controlled experiment with two distinct groups - one exposed to chocolate and the other not. This allows for comparison to determine the impact of chocolate consumption on acne. Option A lacks a control group for comparison. Option C only uses one participant, which is not enough to draw generalizable conclusions. Option D does not have a control group and the order of exposure is reversed, which may affect the results. In summary, choice B is the most appropriate as it includes a control group, clear exposure to the variable of interest, and enables comparison between the two groups.