HESI A2 Biology Practice Test

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: A

Rationale: The correct answer is A: The nucleus. DNA is stored in the nucleus of a cell because it contains the genetic material that carries instructions for the cell's functions. The nucleus is specifically designed to protect and regulate access to the DNA. Ribosomes (B) are responsible for protein synthesis, not DNA storage. Endoplasmic reticulum (C) is involved in protein and lipid synthesis, but not DNA storage. Mitochondria (D) have their own DNA, but the majority of the cell's DNA is stored in the nucleus.

Correct Answer: A

Rationale: Epithelial tissue is primarily found lining the organs, such as the skin, digestive tract, and respiratory tract. This tissue serves as a protective barrier and aids in absorption and secretion. The other choices, heart muscle, tendons, and spinal cord, are not locations where epithelial tissue is typically found. Heart muscle is cardiac muscle tissue, tendons are composed of dense regular connective tissue, and the spinal cord consists of nervous tissue. Therefore, the correct answer is A, organ lining, as it aligns with the typical locations of epithelial tissue in the body.

Correct Answer: B

Rationale: To focus an image using a compound microscope, adjusting the fine adjustment is correct as it allows for precise focusing when switching magnifications. Coarse adjustment is only used initially to bring the specimen into view, while the stage adjustment is used to center the specimen. Therefore, B is correct as it ensures clear and sharp image focus without unnecessary readjustments. Choices A and C are incorrect as they do not address the specific need for precise focusing when changing magnifications, leading to potential blurriness or loss of focus in the image.

Correct Answer: A

Rationale: The correct answer is A: A segment of DNA. Genes are segments of DNA that contain the instructions for building proteins and controlling various processes in an organism. DNA is the genetic material that carries hereditary information and is passed down from parents to offspring. Option B is incorrect because genes are not bead-like structures on chromosomes but are located within chromosomes. Option C is incorrect because genes are not protein molecules themselves but may code for proteins. Option D is incorrect because genes are not made up of RNA but rather DNA.