HESI A2
HESI A2 Practice Test Biology
1. Which of the following cell types has no nucleus?
- A. platelet
- B. red blood cell
- C. white blood cell
- D. phagocyte
Correct answer: B
Rationale: The correct answer is B, red blood cell. In humans, red blood cells do not have a nucleus. This unique feature allows them to have more space to carry oxygen efficiently. Platelets (choice A), white blood cells (choice C), and phagocytes (choice D) all have nuclei. Platelets are cell fragments, while white blood cells and phagocytes are types of immune cells that contain a nucleus for DNA and cellular functions.
2. If a test has poor internal consistency, which statement is true?
- A. The test produces different results at different times.
- B. The items do not correlate or measure similar things.
- C. The test produces different results depending on the researcher.
- D. The items never vary even when the test environment changes.
Correct answer: B
Rationale: Correct answer: If a test has poor internal consistency, it means that the items do not correlate or measure similar things. This lack of correlation indicates that the items in the test are not measuring the same underlying construct or concept, leading to unreliable results. Choice A is incorrect because poor internal consistency is not about producing different results at different times but rather about the lack of correlation among items. Choice C is incorrect because the issue lies within the test itself, not with different researchers. Choice D is incorrect because poor internal consistency implies that the items do vary in their measurement, contributing to the unreliability of the test.
3. Why is the nucleus important in a cell?
- A. It stores the DNA
- B. It supports the cell
- C. It makes protein
- D. It makes energy out of food
Correct answer: A
Rationale: The nucleus is important in a cell because it stores the DNA, which contains the genetic information necessary for the cell's function and replication. This genetic material controls the cell's activities and characteristics. Choices B, C, and D are incorrect because supporting the cell, making proteins, and producing energy are functions typically associated with other cell organelles like the cytoskeleton, ribosomes, and mitochondria, respectively.
4. What type of cells possess a cell membrane?
- A. Prokaryotic cells only
- B. Eukaryotic cells only
- C. Both prokaryotic and eukaryotic cells
- D. None of the above
Correct answer: C
Rationale: Cell membranes are present in both prokaryotic and eukaryotic cells. The cell membrane serves as a barrier that encloses the cell contents and regulates the entry and exit of substances in and out of the cell. It is a fundamental structure found in all types of cells, regardless of whether they are prokaryotic (lacking a nucleus) or eukaryotic (containing a nucleus). Choice A is incorrect because eukaryotic cells also possess cell membranes. Choice B is incorrect as prokaryotic cells, such as bacteria, also have cell membranes. Choice D is incorrect as both prokaryotic and eukaryotic cells have cell membranes.
5. Which of the following is an example of human error in an experiment?
- A. an imperfectly calibrated scale
- B. contaminating a sterile sample by breathing on it
- C. a draft in the laboratory slightly changing the temperature of a liquid
- D. failure to account for wind speed when measuring distance traveled
Correct answer: B
Rationale: Contaminating a sterile sample by breathing on it is an example of human error in an experiment because it involves an action directly caused by the researcher that compromises the integrity of the sample. Breathing on a sterile sample introduces external contaminants that can affect the results. Choices A, C, and D involve factors not directly under the researcher's control or are technical errors that do not involve direct human actions.
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