HESI A2 Biology Practice Test

Correct Answer: A

Rationale: The correct answer is A because the nucleus stores the cell's genetic material, DNA, which contains instructions for cell function and growth. This is crucial for cell division, protein synthesis, and overall cell activities. Choice B is incorrect because the nucleus does not provide structural support to the cell. Choice C is incorrect as protein synthesis primarily occurs in the ribosomes. Choice D is incorrect as energy production from food takes place in the mitochondria, not the nucleus.

Correct Answer: D

Rationale: The correct answer is D: species. Within the biological hierarchical system, species is the least inclusive category. A species consists of organisms that can interbreed and produce fertile offspring. Moving up the hierarchy, species are grouped into genera, then families, orders, classes, phyla, and finally kingdoms. Phylum (A), order (B), and kingdom (C) are all more inclusive categories than species. Phylum includes multiple classes, order includes multiple families, and kingdom includes multiple phyla. Therefore, species is the least inclusive category within this system.

Correct Answer: A

Rationale: The correct answer is A: Connective tissue. Fat is a type of adipose tissue, which is a specialized form of connective tissue that stores energy in the form of fat cells. Connective tissue provides support, structure, and insulation to the body. Muscle tissue (B) is responsible for movement, nervous tissue (C) transmits signals, and epithelial tissue (D) forms protective barriers. Fat does not perform these functions, hence choices B, C, and D are incorrect.

Correct Answer: B

Rationale: Enzymes are typically proteins because they are biological catalysts made up of amino acids. Proteins have specific structures that allow them to bind to substrates and speed up chemical reactions. Fats, sugars, and neurons do not possess the specific structural properties required for enzyme function. Therefore, the correct answer is B (Proteins).

Correct Answer: D

Rationale: The correct answer is D because in DNA, adenine (A) always pairs with thymine (T), forming two hydrogen bonds. This is known as complementary base pairing, essential for DNA replication and maintenance. Options A, B, and C are incorrect as they do not demonstrate the complementary base pairing rule observed in DNA. Option A (A and G) is incorrect because adenine pairs with thymine, not guanine. Option B (A and C) is incorrect because adenine pairs with thymine, not cytosine. Option C (A and A) is incorrect because in DNA, adenine always pairs with thymine, not with itself.