HESI A2
Biology HESI A2 Practice Test
1. What are the three main events of the haploid cell cycle?
- A. DNA replication, mitosis, and cytokinesis
- B. DNA replication, meiosis, and cytokinesis
- C. DNA replication, cytokinesis, and degradation
- D. Mitosis, meiosis, and apoptosis
Correct answer: A
Rationale: In the haploid cell cycle, the three main events are DNA replication, where the cell's genetic material is duplicated; mitosis, which is the division of the nucleus to ensure each daughter cell receives a complete set of chromosomes; and cytokinesis, the division of the cell cytoplasm to separate the two daughter cells. Meiosis is not part of the haploid cell cycle as it occurs in diploid cells to produce haploid gametes. Apoptosis is a process of programmed cell death and is not a routine event in the cell cycle. Therefore, the correct answer is A. Choices B, C, and D are incorrect as meiosis and apoptosis are not part of the haploid cell cycle, and degradation is not a typical event in the cell cycle.
2. When plants do not receive enough water, their photosynthetic rate drops. This is because:
- A. water is a raw material for the light reactions in photosynthesis
- B. carbon dioxide is not available
- C. water provides the carbon atoms used to make sugar
- D. not enough oxygen is produced to keep fermentation running
Correct answer: A
Rationale: When plants do not receive enough water, their photosynthetic rate drops because water is a raw material required for the light reactions in photosynthesis. In the light reactions, water is split to provide electrons, which are then utilized to produce energy carriers used in converting carbon dioxide into glucose during the Calvin cycle. Therefore, without sufficient water, the light reactions cannot proceed effectively, ultimately leading to a decrease in photosynthetic rate. Choice B is incorrect because carbon dioxide is a separate raw material needed for the Calvin cycle, not the light reactions. Choice C is incorrect as water provides electrons, not carbon atoms, for photosynthesis. Choice D is incorrect because fermentation is not directly related to photosynthesis; oxygen is produced during photosynthesis, not fermentation.
3. The phases of mitosis include:
- A. Prophase, interphase, metaphase, anaphase, and telophase
- B. Prophase, prophase, metaphase, anaphase, and cytokinesis
- C. Prophase, prometaphase, metaphase, anaphase, and telophase
- D. Prophase, interphase, prophase, anaphase, and telophase
Correct answer: C
Rationale: The correct phases of mitosis are prophase, prometaphase, metaphase, anaphase, and telophase. Prophase is the first phase where chromatin condenses into chromosomes, the nuclear envelope breaks down, and the mitotic spindle forms. Prometaphase follows prophase, involving the full disintegration of the nuclear envelope and the attachment of spindle fibers to the kinetochores of the chromosomes. Metaphase is where chromosomes align along the metaphase plate. Anaphase is the phase where sister chromatids separate and move towards opposite poles. Telophase marks the final stage of mitosis, involving the decondensation of chromosomes and the reformation of the nuclear envelope. Choice A is incorrect because it includes interphase, which is not a phase of mitosis. Choice B is incorrect as it repeats prophase, which is the initial phase. Choice D is incorrect because it includes interphase and repeats prophase.
4. Which of the following is true of optical microscopy?
- A. Utilizes scanning electrons
- B. Utilizes visible light
- C. Utilizes dye for samples
- D. More than one of the above is true
Correct answer: D
Rationale: The correct answer is D, 'More than one of the above is true.' Optical microscopy utilizes visible light (Choice B) and often involves the use of dyes for samples (Choice C). Using dyes helps enhance contrast, making it easier to visualize the structures being observed. Choice A is incorrect as optical microscopy does not utilize scanning electrons, but rather visible light.
5. A cell is in a solution in which the concentration of solutes is higher inside the cell than outside the cell. What would you expect to happen to the cell?
- A. It will swell and possibly burst.
- B. It will shrivel and shrink.
- C. It will maintain its current size.
- D. It will grow a supportive cell wall.
Correct answer: A
Rationale: When a cell is in a solution where the concentration of solutes is higher inside the cell than outside, it is in a hypertonic environment. In this situation, water will move into the cell in an attempt to equalize the concentration of solutes on both sides of the cell membrane through the process of osmosis. As a result, the cell will swell as it takes in more water, potentially leading to bursting or cell lysis. Choice B is incorrect because a cell in a hypertonic solution will not shrivel and shrink due to water moving into the cell. Choice C is incorrect because the cell will not maintain its current size; it will swell. Choice D is incorrect because growing a supportive cell wall is not the immediate response to being in a hypertonic environment.
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