Biology HESI A2 2024

Correct Answer: C

Rationale: The correct answer is C because yeast carries out fermentation, producing ethanol and carbon dioxide. During fermentation, yeast breaks down sugars in the dough into ethanol and carbon dioxide gas. The carbon dioxide gas gets trapped in the dough, causing it to rise. Choice A is incorrect because yeast does not engage in photosynthesis. Choice B is incorrect because yeast does not carry out photosynthesis at all. Choice D is incorrect because yeast primarily produces carbon dioxide through fermentation, not aerobic respiration.

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: B

Rationale: During interphase, the cell prepares for division by replicating its DNA, including the chromosomes. This occurs before the actual cell division stages of mitosis or meiosis. Prophase is the stage where chromosomes condense, not replicate. Anaphase is when sister chromatids separate, and telophase is the final stage where chromosomes de-condense. Therefore, the correct answer is B (Interphase) as it is the specific phase where chromosome replication occurs.

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: D

Rationale: The correct answer is D: Salmonella. Binary fission is a form of asexual reproduction where a single organism divides into two identical organisms. Salmonella is a bacterium that reproduces through binary fission. Mushrooms reproduce via spores, blue whales and rainbow trout reproduce sexually. Therefore, Salmonella is the only organism among the choices that reproduces via binary fission.