HESI A2 Biology Practice Test

Correct Answer: D

Rationale: The correct answer is D: They are denoted Aa. Heterozygous traits refer to the presence of different alleles at a specific gene locus. In this case, A and a represent two different alleles for the same trait. When an individual is heterozygous, one allele is dominant (A) and the other is recessive (a). Therefore, the correct notation for a heterozygous trait is Aa. Option A is incorrect because heterozygous traits are not haploid (having one set of chromosomes), but diploid (having two sets). Option B is incorrect as it denotes a homozygous dominant genotype. Option C is incorrect as it denotes a homozygous recessive genotype.

Correct Answer: B

Rationale: The correct answer is B: smooth ER. The smooth ER is responsible for detoxifying multiple molecules through processes like drug metabolism and lipid synthesis. It contains enzymes that help break down toxins. The rough ER is primarily involved in protein synthesis, so it is not directly related to detoxification. Lysosomes are involved in breaking down cellular waste and are not specialized for detoxification. The Golgi apparatus is responsible for packaging and modifying proteins for transport, not detoxifying molecules. Therefore, the smooth ER is the most suitable organelle for detoxifying multiple molecules in a cell.

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.

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: D

Rationale: The correct answer is D: cellular respiration and fermentation. Cellular respiration is the process by which cells convert glucose and oxygen into ATP, providing energy for the cell. Fermentation is an anaerobic process that also produces ATP but does not require oxygen. Both pathways are catabolic, breaking down molecules to release energy. Option A is incorrect because protein synthesis is an anabolic process that builds proteins and does not directly produce energy. Option B is incorrect because cellular respiration and glycolysis are both energy-producing pathways, not protein synthesis. Option C is incorrect because it includes fermentation and glycolysis, omitting cellular respiration, which is a major pathway for energy production in cells.