HESI A2
HESI A2 Practice Test Biology
1. Which of the following describes how a bacterium reproduces?
- A. Mitosis
- B. Meiosis
- C. Binary fission
- D. Cytokinesis
Correct answer: C
Rationale: Bacteria reproduce through a process called 'binary fission.' During binary fission, a bacterium duplicates its DNA and then divides into two identical daughter cells. This method is the primary way bacteria replicate. Choice A, 'Mitosis,' is incorrect because mitosis is a process specific to eukaryotic cells, where the nucleus divides to produce two identical nuclei. Choice B, 'Meiosis,' is incorrect as meiosis is a specialized type of cell division that produces gametes with half the chromosome number. Choice D, 'Cytokinesis,' is not the correct answer as cytokinesis is the physical process of cell division, which occurs after the genetic material has been divided in mitosis or meiosis.
2. A pencil measures 8cm long. What is this in mm?
- A. 80 mm
- B. 800 mm
- C. 8 mm
- D. 0.8 mm
Correct answer: A
Rationale: To convert centimeters to millimeters, you need to multiply by 10 since 1 centimeter is equal to 10 millimeters. Therefore, 8 cm x 10 mm/cm = 80 mm. The pencil measures 8 cm, which is equivalent to 80 mm when converted. Choice A is correct as it correctly converts 8 cm to mm by multiplying it by 10. Choices B, C, and D are incorrect because they do not apply the correct conversion factor.
3. 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.
4. Which of the following types of hormones can diffuse through the cell membrane to bind to receptors inside the cell and stimulate a chemical response to a target cell?
- A. fat-soluble hormones
- B. amino acid derivatives
- C. hydrophilic hormones
- D. water-soluble hormones
Correct answer: A
Rationale: The correct answer is A: fat-soluble hormones. Fat-soluble hormones are able to diffuse through the cell membrane to bind to receptors inside the cell. This is because they are lipophilic, allowing them to cross the lipid bilayer easily. Once inside the cell, fat-soluble hormones can directly affect gene expression or cell function. Choice B, amino acid derivatives, and choice C, hydrophilic hormones, are not able to diffuse through the cell membrane as they are not lipophilic. Therefore, they cannot bind to receptors inside the cell. Choice D, water-soluble hormones, also cannot diffuse through the cell membrane as it is hydrophilic, making it unable to reach receptors inside the cell.
5. Which two bases are purines?
- A. Adenine (A)
- B. Cytosine (C)
- C. Thymine (T)
- D. Guanine (G)
Correct answer: A
Rationale: Adenine (A) and guanine (G) are the two bases that are purines. Purines are characterized by a double-ring structure containing two carbon rings, distinguishing them from pyrimidines. Adenine and guanine are purines because they possess this unique double-ring structure. Therefore, choices A and D, adenine and guanine, respectively, are the correct answers. Choices B and C, cytosine and thymine, are pyrimidines and do not exhibit the double-ring structure characteristic of purines.
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