HESI A2
HESI A2 Biology 2024
1. Which organelle is the site of energy production?
- A. Mitochondrion
- B. Vacuole
- C. Cell membrane
- D. Ribosome
Correct answer: A
Rationale: The correct answer is A: Mitochondrion. The mitochondrion is the site of energy production in a cell. It is often referred to as the powerhouse of the cell because it is where cellular respiration occurs, generating energy in the form of adenosine triphosphate (ATP) through processes like the citric acid cycle and oxidative phosphorylation. The other organelles listed play different roles in the cell - vacuoles store materials, the cell membrane regulates the movement of substances in and out of the cell, and ribosomes are involved in protein synthesis.
2. Why do gardeners sometimes use salt to get rid of slugs?
- A. The salt moves from the exterior into the slug’s body.
- B. The salt causes water in the slug to move outward.
- C. The salt and slug slime merge to form a new compound.
- D. The salt’s corrosiveness breaks down the slug’s cell walls.
Correct answer: D
Rationale: Gardeners use salt to get rid of slugs because salt is corrosive and breaks down the slug's cell walls. When the slug comes into contact with salt, the salt draws moisture out of the slug's body, causing dehydration and ultimately leading to the slug's death. Choices A, B, and C are incorrect because the primary mechanism of salt in eliminating slugs is its corrosive action on the slug's body, not the movement of salt into the slug's body, outward movement of water in the slug, or merging with slug slime to form a new compound.
3. How many chromosomes do sperm and egg produce in meiosis?
- A. 46
- B. 23
- C. 45
- D. 24
Correct answer: B
Rationale: Sperm and egg cells undergo meiosis to form gametes with half the number of chromosomes found in somatic cells. Each sperm and egg cell produces 23 chromosomes through meiosis. Choice A is incorrect because 46 chromosomes represent the diploid number found in somatic cells. Choice C is incorrect as it is an uncommon number for chromosome production in human gametes. Choice D is incorrect as the total number of chromosomes in sperm or egg cells is 23, not 24.
4. During which phase of cell division do the chromosomes replicate?
- A. Prophase
- B. Interphase
- C. Anaphase
- D. Telophase
Correct answer: B
Rationale: Chromosomes replicate during the interphase of the cell cycle. Interphase is the phase where the cell prepares for division by undergoing various activities such as growth, DNA replication, and protein synthesis. During DNA replication in interphase, each chromosome in the cell is duplicated to form two sister chromatids, which are then separated during cell division. Prophase is the phase where the chromosomes condense, and the nuclear envelope breaks down. Anaphase is the phase where sister chromatids are pulled apart towards opposite poles of the cell. Telophase is the phase where the nuclear envelope reforms, and chromosomes begin to decondense.
5. The apical side of an epithelial cell:
- A. Is exposed to fluid or air
- B. Is on the bottom side of the cell
- C. Does not allow any substances to pass through
- D. None of the above
Correct answer: A
Rationale: The apical side of an epithelial cell is the top side, which is typically exposed to fluids, air, or the inside of an organ. This side allows substances to pass through it, facilitating the absorption, secretion, or excretion of various substances. Choice B is incorrect as the apical side is not on the bottom but the top side. Choice C is incorrect as the apical side does allow substances to pass through. Choice D is incorrect as there are characteristics associated with the apical side.
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