HESI A2 Biology Practice Test

Correct Answer: A

Rationale: The correct answer is A because water is a raw material for the light reactions in photosynthesis, specifically in the process of photolysis where water is split to release electrons for the photosystems. Without enough water, this process is hindered, leading to a drop in photosynthetic rate. Choice B is incorrect because carbon dioxide availability affects the Calvin cycle, not the light reactions. Choice C is incorrect as carbon atoms for sugar come from carbon dioxide, not water. Choice D is incorrect because fermentation is not directly related to the availability of water in photosynthesis.

Correct Answer: A

Rationale: The correct answer is A because water's polarity leads to hydrogen bonding, high specific heat value, and versatile solvent properties. Polarity in water results from its unequal sharing of electrons between hydrogen and oxygen atoms, creating a partial positive and negative charge. This polarity allows water molecules to form hydrogen bonds, which contribute to its high specific heat value, meaning water can absorb and release heat without drastic temperature changes. Additionally, water's polarity enables it to act as a versatile solvent, dissolving many substances. Choices B, C, and D are incorrect because they mention incorrect types of bonding and specific heat values that do not align with water's characteristics.

Correct Answer: D

Rationale: Cytokinesis occurs to physically separate the two daughter cells after cell division. This process ensures that each daughter cell receives a complete set of organelles and genetic material. The correct answer, choice D, states that daughter cells can divide, which aligns with the purpose of cytokinesis. Choices A and B are incorrect as they do not directly relate to the process of cytokinesis. Choice C is also incorrect as cytokinesis is not primarily involved in killing bacteria, but rather in ensuring successful cell division.

Correct Answer: A

Rationale: The correct answer is A: Bacteria. Eukaryotic cells have a defined nucleus and membrane-bound organelles, which bacteria lack. Dogs, humans, and onions are all multicellular organisms that possess eukaryotic cells. Bacteria, being prokaryotic, do not have a distinct nucleus or membrane-bound organelles, leading to the conclusion that they do not have eukaryotic cells.

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.