HESI A2 Biology Practice Test 2024

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: 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: Active Transport. Active transport moves substances across the cell membrane against the concentration gradient, requiring energy (usually in the form of ATP). This process is crucial for maintaining cellular homeostasis and allowing the cell to accumulate essential molecules. Passive transport (A) does not require energy and moves substances along the concentration gradient. Facilitated diffusion (C) is a type of passive transport that involves the use of transport proteins to move specific molecules across the membrane. Osmosis (D) is the movement of water across a selectively permeable membrane, also considered a type of passive transport.

Correct Answer: A

Rationale: Mitosis is the correct answer as it is the process by which cells divide to form two identical daughter cells for growth, repair, and maintenance. It involves a series of stages such as prophase, metaphase, anaphase, and telophase, ensuring the distribution of genetic material equally. Meiosis is incorrect as it is a process for producing gametes with genetic variation. Binary fission is incorrect as it is a form of asexual reproduction in prokaryotes. Cellular division is too broad and vague, not specifically describing the process of cell division into two identical daughter cells.

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.