HESI A2 Biology Practice Test 2024

Correct Answer: B

Rationale: During metaphase of mitosis, chromosomes align at the cell's equator, forming the metaphase plate. This alignment ensures that during anaphase, sister chromatids separate and move towards opposite poles. Prophase is characterized by chromosome condensation, telophase marks the end of nuclear division. Anaphase involves the actual separation of chromatids. Metaphase is the correct answer as it is the phase where chromosomes are precisely aligned for accurate distribution to daughter cells.

Correct Answer: B

Rationale: The correct answer is B: Lipids. The plasma membrane is primarily composed of lipids, specifically phospholipids, which form a lipid bilayer. This structure provides the membrane with its selective permeability properties. Proteins are also present in the membrane, but they are not the primary composition. Carbohydrates are found on the outer surface of the membrane for cell recognition and signaling. Nucleotides are the building blocks of nucleic acids and are not a major component of the plasma membrane.

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: C

Rationale: The correct answer is C: Cytoskeleton. The cytoskeleton provides structural support to the cell, helps maintain its shape, and allows it to adapt to external stimuli. It is composed of microfilaments, intermediate filaments, and microtubules. Microfilaments (choice A) play a role in cell movement but are not primarily responsible for maintaining cell shape. Cytoplasm (choice B) is the gel-like substance within the cell where organelles are suspended, but it does not directly contribute to maintaining cell shape. Centrioles (choice D) are involved in cell division and organization of microtubules, but they do not primarily help the cell maintain its shape and adapt.

Correct Answer: B

Rationale: The correct answer is B: Communication. The cell membrane serves as a barrier that regulates the passage of materials in and out of the cell. It also plays a crucial role in cell communication by allowing the exchange of signals and molecules with the external environment and other cells. This communication is essential for coordinating various cellular processes and maintaining homeostasis. Other choices are incorrect: A: Energy production - This function is primarily carried out by organelles such as mitochondria and chloroplasts, not the cell membrane. C: Protein synthesis - Protein synthesis occurs in the ribosomes within the cell, not the cell membrane. D: Waste removal - While the cell membrane does play a role in waste removal by allowing certain materials to exit the cell, it is not its main function.