HESI A2 Biology Practice Test 2024

Correct Answer: B

Rationale: The correct answer is B: Gametes. Meiosis is the process of cell division that produces gametes (sex cells) such as sperm and eggs. During meiosis, a diploid cell undergoes two rounds of division to produce four haploid gametes. Somatic cells (choice A) are non-reproductive cells in the body. Zygote (choice C) is a fertilized egg formed by the fusion of sperm and egg, not involved in meiosis. Diploid cells (choice D) have two sets of chromosomes and are the starting cells for meiosis, not the end products. Therefore, gametes are the specific cells involved in meiosis.

Correct Answer: C

Rationale: The correct answer is C: Vacuoles. Plant cells have vacuoles that function as storage for nutrients, waste disposal by containing and breaking down unwanted materials, and protection by regulating turgor pressure to maintain cell structure and protect against external stressors. Nucleus (A) is the control center of the cell, mitochondria (B) are responsible for energy production, and ribosomes (D) are involved in protein synthesis, none of which directly fulfill the functions described in the question.

Correct Answer: B

Rationale: The correct answer is B: Cell Membrane. The cell membrane serves as a selectively permeable barrier that controls the passage of substances into and out of the cell. It is composed of a phospholipid bilayer with embedded proteins that regulate the transport of molecules. The other choices are incorrect because: A: Vacuole - Vacuoles are membrane-bound organelles that mainly store water, ions, and nutrients. They do not control the passage of substances into and out of the cell. C: Nuclear Membrane - The nuclear membrane surrounds the nucleus and regulates the passage of molecules between the nucleus and the cytoplasm. It does not control the passage of substances into and out of the entire cell. D: Cytoplasm - Cytoplasm is the gel-like substance inside the cell that contains organelles. It does not directly control the passage of substances into and out of the cell; instead, it provides a medium for cellular activities to occur.

Correct Answer: C

Rationale: The correct answer is C: Lipids. Plasma membranes are primarily composed of phospholipids, which form a lipid bilayer structure. This lipid bilayer provides a barrier that separates the internal and external environments of the cell. Proteins are also present in the plasma membrane, but they are not the main component. Carbohydrates are found on the surface of the membrane for cell recognition and signaling, but they do not make up the majority of the membrane. Nucleotides are building blocks of nucleic acids like DNA and RNA, not the main constituents of plasma membranes. In summary, lipids are the key component of plasma membranes, forming the structural basis for its function, making choice C the correct answer.

Correct Answer: B

Rationale: The correct answer is B: Mitochondria. Mitochondria are known as the powerhouse of the cell as they produce energy through the process of respiration. They contain enzymes responsible for converting nutrients into ATP, the energy currency of the cell. The nucleus (A) is responsible for storing genetic material, Golgi Apparatus (C) is involved in protein processing and packaging, and Chloroplasts (D) are responsible for photosynthesis in plant cells, not respiration.