HESI A2 Biology Practice Test

Correct Answer: C

Rationale: The correct answer is C because plant cells have a rigid cell wall that prevents them from forming a contractile ring during cell division. The cell wall provides structural support, making it challenging for plant cells to constrict and pinch apart like animal cells. This rigidity limits the flexibility needed for the contractile ring to form and function effectively. Plant cells primarily rely on other mechanisms such as cell plate formation for division. Choices A and B are incorrect as they do not address the specific structural difference between plant and animal cells. Choice D is incorrect as it does not provide any relevant information on the topic.

Correct Answer: A

Rationale: Epithelial cells are correct to be classified as polarized because they have distinct apical and basal surfaces. The apical surface faces the external environment or a body cavity, while the basal surface is anchored to the underlying connective tissue. This polarity is essential for the specialized functions of epithelial cells, such as absorption, secretion, and transportation. Therefore, choice A is the correct answer. Choices B and C are incorrect because epithelial cells are not neutral and are not necessarily larger than other cells. Choice D is incorrect because epithelial cells do have unique characteristics that differentiate them from other cell types.

Correct Answer: A

Rationale: The correct answer is A: Adenine. Adenine is a nucleotide base that consists of two fused carbon rings, making it a purine base. The two rings in adenine are essential for its structure, function, and hydrogen bonding with thymine in DNA. The other choices, B, C, and D, are all pyrimidine bases, which have only one carbon ring. Therefore, adenine is the only base among the options that has two carbon rings, making it the correct answer.

Correct Answer: A

Rationale: The correct answer is A: fat-soluble hormones. Fat-soluble hormones can diffuse through the cell membrane due to their lipophilic nature. Once inside the cell, they can bind to receptors located in the cytoplasm or nucleus to initiate a chemical response. This process allows fat-soluble hormones to directly affect gene expression and protein synthesis within the target cell. In contrast, choices B, C, and D (amino acid derivatives, hydrophilic, and water-soluble hormones) cannot diffuse through the cell membrane and typically bind to receptors on the cell surface to trigger a signaling cascade.

Correct Answer: B

Rationale: The correct answer is B because animal cells do not use chloroplasts to gain energy, they use mitochondria for cellular respiration. Lysosomes in animal cells break down old cells (A) and plant cells have a cell wall (C). Choice D is incorrect as B is false.