HESI A2 Practice Test Biology

Correct Answer: C

Rationale: The correct answer is C: Binary fission. This is because binary fission is a form of asexual reproduction in bacteria where the cell divides into two identical daughter cells. This process does not involve the formation of gametes or genetic recombination, which are characteristics of meiosis. Mitosis is a process seen in eukaryotic cells, not prokaryotic bacteria. Cytokinesis is the final stage of cell division where the cytoplasm divides, which is a part of binary fission but not the overall process of bacterial reproduction.

Correct Answer: B

Rationale: The correct answer is B because lipids are nonpolar molecules, making them hydrophobic and insoluble in water. This is due to their long hydrocarbon chains that repel water molecules. Choice A is incorrect because lipids are composed of fatty acids and glycerol, which are separate components. Choice C is incorrect as lipids do not necessarily contain zinc; this is more common in proteins. Choice D is incorrect because lipids do not form long proteins; proteins are made up of amino acids.

Correct Answer: D

Rationale: The correct answer is D: gradient. A concentration gradient is necessary for cell diffusion to occur, as it drives the movement of particles from an area of higher concentration to an area of lower concentration. This process does not require ATP (choice C) as it is a passive transport mechanism. While water (choice A) is essential for life and plays a role in cell diffusion, it is not the sole requirement. The presence of a membrane (choice B) is important for regulating the diffusion process but is not the direct driving force behind it. Therefore, the concentration gradient is the critical factor necessary for cell diffusion to take place.

Correct Answer: A

Rationale: The correct answer is A: two diploid cells. During mitosis in humans, a single diploid cell divides into two identical diploid cells. This process ensures that each new cell receives a complete set of chromosomes, maintaining the same genetic information. This is essential for growth, repair, and maintenance of tissues in the body. Choices B, C, and D are incorrect because mitosis results in the production of genetically identical diploid cells, not haploid cells or additional copies of diploid cells. Haploid cells are produced through meiosis, not mitosis.

Correct Answer: D

Rationale: During meiosis I, the chromosome number is reduced from diploid to haploid. This occurs during the process of homologous chromosomes separating, resulting in two daughter cells with half the number of chromosomes. In contrast, in S phase, DNA replication occurs, while interphase is a period of cell growth and preparation for cell division. Mitosis is a process where a diploid cell divides into two identical diploid daughter cells, maintaining the same chromosome number. Thus, meiosis I is the only phase where the chromosome number is reduced from diploid to haploid, making it the correct answer.