HESI A2
HESI A2 Biology Practice Test
1. Which one of the following best describes the function of a cell membrane?
- A. It controls the substances entering and leaving the cell.
- B. It maintains the cell's shape.
- C. It controls the substances entering the cell.
- D. It supports the cell's structures.
Correct answer: A
Rationale: The correct answer is A. The function of a cell membrane is to control the substances entering and leaving the cell. The cell membrane is selectively permeable, allowing it to regulate the movement of ions and molecules in and out of the cell to maintain internal balance and proper function. Choice B is incorrect because while the cell membrane does provide some structural support, its primary function is not to maintain the cell's shape. Choice C is incorrect because the cell membrane controls both the substances entering and leaving the cell, not just those entering. Choice D is incorrect as the primary function of the cell membrane is not to support the cell's structures but to regulate the movement of substances.
2. 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.
3. What process involves the movement of water molecules through a selectively permeable membrane?
- A. Diffusion
- B. Osmosis
- C. Active Transport
- D. Facilitated Diffusion
Correct answer: B
Rationale: Osmosis is the process specifically involving the movement of water molecules through a selectively permeable membrane, from an area of higher water concentration to an area of lower water concentration. This process helps balance concentrations on both sides of the membrane. Choice A, Diffusion, refers to the movement of particles from an area of higher concentration to an area of lower concentration, not specific to water. Choice C, Active Transport, requires energy to move substances against their concentration gradient, unlike osmosis. Choice D, Facilitated Diffusion, involves the use of transport proteins to move specific substances across membranes, not limited to water molecules.
4. Athletes are often concerned with the question of what they need in their diets to increase muscle mass and strength. What biologic molecule would you recommend that would accomplish this?
- A. carbohydrates
- B. proteins
- C. lipids
- D. nucleic acids
Correct answer: B
Rationale: Proteins are essential for building and repairing muscle tissue. They contain amino acids, which are the building blocks of muscles. Athletes looking to increase muscle mass and strength should focus on consuming adequate amounts of high-quality proteins in their diets. Carbohydrates provide energy for workouts, lipids are important for overall health but do not directly contribute to muscle building, and nucleic acids are involved in genetic activities rather than muscle growth.
5. The difference between diploid and haploid is as follows:
- A. Diploid organisms are multicellular
- B. Diploid cells are somatic
- C. Diploid cells have two sets of homologous chromosomes
- D. More than one of the above is true
Correct answer: D
Rationale: Option B correctly states that diploid cells are somatic cells that make up the body tissues and organs in an organism, while haploid cells are gametes involved in sexual reproduction. Option C accurately differentiates diploid and haploid cells based on their chromosome sets – diploid cells have two sets of homologous chromosomes (one from each parent), whereas haploid cells have one set of unpaired chromosomes. Therefore, the correct choice is D, as both statements in options B and C are accurate descriptions of the differences between diploid and haploid cells. Option A is incorrect because diploid and haploid refer to the number of sets of chromosomes in a cell, not whether the organism is multicellular or not.
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