Biology HESI A2 Practice Test

Correct Answer: B

Rationale: The correct answer is B: Cell wall. Plant cells have a rigid cell wall made of cellulose, which provides structural support and protection. Animal cells lack cell walls and instead have a flexible cell membrane for support. Choices A, C, and D (Cell membrane, Ribosome, Chloroplast) are present in both plant and animal cells. The cell membrane controls what enters and leaves the cell, ribosomes are responsible for protein synthesis, and chloroplasts are the site of photosynthesis in plant cells.

Correct Answer: C

Rationale: The correct answer is C: epididymis. The epididymis is the structure in the male reproductive system that stores spermatozoa during the maturation process. Sperm are produced in the testes and then move to the epididymis for storage and maturation before being ejaculated. The vas deferens is the tube that carries mature sperm from the epididymis to the urethra during ejaculation. The scrotum is the external sac that holds the testes and helps regulate their temperature. The testicular artery supplies blood to the testes but is not directly involved in storing spermatozoa.

Correct Answer: C

Rationale: The correct answer is C: prokaryotic. Prokaryotic cells lack membrane-bound organelles and a defined nucleus. They have a simple structure with genetic material floating freely in the cytoplasm. Eukaryotic cells (choice A) have membrane-bound organelles and a nucleus. Embryonic (choice B) refers to a developmental stage, not a cell classification. Symbiotic (choice D) relates to a mutually beneficial relationship between two organisms, not cell classification. In summary, prokaryotic cells are characterized by their lack of membrane-bound organelles and nucleus, distinguishing them from eukaryotic cells, embryonic stages, and symbiotic relationships.

Correct Answer: A

Rationale: The correct answer is A: 18 chromosomes. During meiosis, the chromosomes are halved, resulting in gametes with half the number of chromosomes as the parent cell. Since the initial cell had 72 chromosomes, each gamete will have 36 chromosomes after the first division (meiosis I), and then after the second division (meiosis II), each gamete will have 18 chromosomes. Therefore, choice A is correct. Choices B, C, and D are incorrect as they do not reflect the halving of chromosome number during meiosis.

Correct Answer: C

Rationale: Exocytosis is the process by which cells expel waste products out of the cell. It is essential for maintaining cellular homeostasis and preventing the accumulation of toxic substances. Through exocytosis, cells can remove waste such as by-products of metabolism or harmful substances. This process helps keep the cell environment clean and functional. A: Cells obtain energy through processes like cellular respiration, not exocytosis. B: Cells defend against invaders through immune responses, not exocytosis. D: Cell division occurs through processes like mitosis, not exocytosis.