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: B

Rationale: The correct answer is B: heterozygous. In a heterozygous situation, an individual carries two different alleles for a particular gene, resulting in different forms of the allele. This creates genetic diversity and can lead to varying phenotypic expressions. The term phenotype (A) refers to the physical characteristics of an organism, not specifically related to different forms of alleles. Homolog (C) refers to chromosomes that are similar in structure and function but not necessarily different forms of alleles. Homozygous (D) describes a situation where an individual carries two identical alleles for a gene, which does not involve different forms of alleles.

Correct Answer: B

Rationale: The scientist needs 12mL, which is equivalent to 0.012L. Since the bottle holds 12L, it contains more than enough solution. Therefore, choice B is correct. Choice A is incorrect because the scientist needs less than the total amount in the bottle. Choice C is incorrect because the scientist actually has more than enough. Choice D is also incorrect as the scientist does have more than required.

Correct Answer: A

Rationale: The correct answer is A: Ribosome. Ribosomes are the organelles responsible for protein synthesis in the cell. They can be found in the cytoplasm or attached to the endoplasmic reticulum. Ribosomes read the mRNA and assemble amino acids into proteins through a process called translation. Summary of other choices: B: Chloroplast - responsible for photosynthesis in plant cells. C: Lysosome - contains enzymes for digesting waste materials. D: Mitochondrion - produces ATP through cellular respiration. These organelles are not directly involved in protein synthesis, making them incorrect choices for this question.

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.