HESI A2
Biology HESI A2 Practice Test
1. Which organelle is responsible for making proteins?
- A. Ribosome
- B. Chloroplast
- C. Lysosome
- D. Mitochondrion
Correct answer: A
Rationale: Ribosomes are the organelles responsible for protein synthesis within the cell. They are the sites where amino acids are linked together to form proteins based on the instructions carried by mRNA (messenger RNA). Ribosomes can be found free-floating in the cytoplasm or attached to the endoplasmic reticulum, and they play a crucial role in translating genetic information into proteins. Chloroplasts are responsible for photosynthesis, lysosomes are involved in digestion and waste removal, and mitochondria are known as the powerhouse of the cell responsible for energy production through cellular respiration. Therefore, the ribosome is the correct organelle responsible for making proteins.
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. The cell membrane consists of a bilayer of phospholipids with proteins, cholesterol, and glycoproteins. What does this bilayer create?
- A. Impermeable
- B. Permeable
- C. Selectively permeable
- D. Selectively impermeable
Correct answer: C
Rationale: The correct answer is 'Selectively permeable.' The cell membrane's bilayer structure allows it to be selectively permeable, meaning it can control the passage of substances. This property enables the membrane to regulate the entry and exit of specific molecules, ions, and other substances. Choice A, 'Impermeable,' is incorrect as the cell membrane is not completely impermeable and does allow certain substances to pass through. Choice B, 'Permeable,' is also incorrect as it does not address the selective nature of the membrane. Choice D, 'Selectively impermeable,' is a contradictory term and does not accurately describe the cell membrane's function.
4. A cell containing 12 chromosomes divides into daughter cells in mitosis. How many chromosomes are in each daughter cell?
- A. 3
- B. 6
- C. 12
- D. 24
Correct answer: C
Rationale: During mitosis, the cell undergoes nuclear division without changing the number of chromosomes. Therefore, the daughter cells produced will have the same number of chromosomes as the parent cell. In this case, since the parent cell contains 12 chromosomes, each daughter cell will also have 12 chromosomes. Choices A, B, and D are incorrect because during mitosis, the chromosome number remains the same, and daughter cells inherit the same number of chromosomes as the parent cell.
5. Which statement is untrue?
- A. RNA is single-stranded.
- B. RNA contains uracil.
- C. DNA codes for proteins.
- D. DNA cannot be altered.
Correct answer: D
Rationale: DNA can be altered through various processes such as mutations, genetic engineering, and epigenetic modifications. Changes in DNA can occur naturally or through external influences, leading to variations in the genetic code. Therefore, the statement that DNA cannot be altered is untrue. Choices A, B, and C are true statements. RNA is indeed single-stranded, RNA contains uracil instead of thymine, and DNA serves as a template for protein synthesis.
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