HESI A2
Biology HESI A2 Practice Test
1. Which is true of gametes?
- A. They are diploid cells
- B. They are haploid cells
- C. They are somatic
- D. A & C are true
Correct answer: B
Rationale: Gametes are sex cells (sperm and eggs) that are involved in sexual reproduction. They are haploid cells, meaning they have half the number of chromosomes (n) compared to diploid cells. This is necessary for the formation of a diploid zygote when two gametes unite during fertilization. Somatic cells are non-reproductive cells in the body, so they are not gametes. Choice A is incorrect because gametes are not diploid but haploid. Choice C is incorrect because gametes are not somatic cells.
2. Convert the percentage to a decimal: 38%
- A. 3.8
- B. 0.38
- C. 0.038
- D. 38.0
Correct answer: B
Rationale: To convert a percentage to a decimal, you divide the percentage by 100. Therefore, 38% as a decimal is 0.38 (38 ÷ 100 = 0.38). Choice A, 3.8, is incorrect as it is equivalent to 380%. Choice C, 0.038, is incorrect as it represents 3.8%. Choice D, 38.0, is incorrect as it is still in percentage form.
3. Which of the following are considered the most important molecules in biology?
- A. Carbohydrates, lipids, protein, and nucleic acids
- B. Carbohydrates, lipids, protein, and calcium
- C. Carbohydrates, lipids, protein, and sulfur
- D. Carbohydrates, lipids, protein, and iron
Correct answer: A
Rationale: The correct answer is A: Carbohydrates, lipids, protein, and nucleic acids are considered the most important molecules in biology. Carbohydrates are essential for providing energy, lipids for storing energy and forming cell membranes, proteins for various structural and functional roles, and nucleic acids (DNA and RNA) for storing genetic information. Choices B, C, and D are incorrect because while carbohydrates, lipids, and proteins are crucial biomolecules, calcium, sulfur, and iron are not considered among the most important molecules in biology.
4. A patient who is querulous might be guilty of ______.
- A. Stealing
- B. Questioning
- C. Overeating
- D. Complaining
Correct answer: D
Rationale: The correct answer is D, 'Complaining.' 'Querulous' means complaining in a petulant or whining manner. This word describes someone who is constantly finding fault and is difficult to please. Choices A, B, and C are incorrect because 'querulous' specifically refers to complaining behavior, not stealing, questioning, or overeating.
5. Cobalt-60 has a half-life of 5 years. If you start with 20 g of cobalt-60, how much is left after 10 years?
- A. 15 g
- B. 10 g
- C. 5 g
- D. 2.5 g
Correct answer: C
Rationale: Cobalt-60's half-life of 5 years means that after 5 years, half of the initial amount remains. Therefore, after 10 years, a quarter (half of a half) of the initial amount will remain. Starting with 20 g, after 10 years, 5 g of cobalt-60 will be left. Choice A (15 g) is incorrect because it assumes a linear decrease, not considering the exponential decay characteristic of radioactive substances. Choice B (10 g) is incorrect as it overlooks that after 10 years, more decay has occurred. Choice D (2.5 g) is incorrect as it represents only an eighth of the initial amount after 10 years, not a quarter.
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