Biology HESI A2 Practice Test

Correct Answer: A

Rationale: The correct answer is A: electron transport chain. This step in cellular respiration produces the greatest amount of ATP through oxidative phosphorylation, where electrons are passed through a series of protein complexes to generate a proton gradient used to produce ATP. In contrast, glycolysis only produces a small amount of ATP, the citric acid cycle produces some ATP but not as much as the electron transport chain, and fermentation doesn't produce ATP through oxidative phosphorylation. Therefore, the electron transport chain is the most efficient step in ATP production during cellular respiration.

Correct Answer: A

Rationale: The correct answer is A: Atmosphere. The atmosphere is the layer of gases that surrounds a planet. It consists of different layers, including the stratosphere and troposphere mentioned in the other choices. The biosphere refers to the regions on Earth where living organisms exist, not the gases surrounding the planet. Therefore, the correct term for the mixture of gases surrounding a planet is the atmosphere.

Correct Answer: C

Rationale: Correct Answer: C Rationale: 1. Sexual reproduction involves two cells (sperm and egg) contributing genetic material to offspring, leading to genetic variation. 2. Greater genetic variation in offspring helps in adapting to changing environments and enhances species survival. 3. Asexual reproduction involves a single parent cell dividing to produce genetically identical offspring. 4. Option A is incorrect as sexual reproduction does not result in half of the cells being identical to the original cell. 5. Option B is incorrect as asexual reproduction does not result in greater variation, it produces genetically identical offspring. 6. Option D is incorrect as sexual reproduction involves two cells contributing genetic material, leading to variation.

Correct Answer: A

Rationale: The correct answer is A because the apical side of an epithelial cell is the top surface that is exposed to fluid or air. This surface is specialized for absorption, secretion, and protection. Choice B is incorrect because the apical side is actually the top side of the cell, not the bottom. Choice C is incorrect because the apical side allows substances to pass through via various transport mechanisms such as active transport, facilitated diffusion, or simple diffusion. Choice D is incorrect because the apical side of an epithelial cell is indeed exposed to fluid or air, making it the correct answer.

Correct Answer: B

Rationale: The correct answer is B because the Krebs cycle involves the oxidation of acetyl CoA, a product of glycolysis, leading to the production of NADH and FADH2. Choice A is incorrect because the proteins are not directly involved in the Krebs cycle. Choice C is incorrect because protons are not passed along a gradient in the Krebs cycle; they are used in the electron transport chain to produce ATP. Choice D is incorrect because the Krebs cycle is not known as the glycolic acid cycle; glycolysis is the pathway that produces glycolic acid.