HESI A2
HESI A2 Biology Practice Test
1. What is the purpose of the mitochondria?
- A. Control the cell
- B. Create energy
- C. Create proteins
- D. Package waste for removal
Correct answer: B
Rationale: The correct answer is B: Create energy. The primary purpose of the mitochondria is to generate energy for the cell. Mitochondria are known as the 'powerhouses' of the cell because they produce ATP (adenosine triphosphate), which is the energy currency used by cells to carry out various functions and processes. Choice A is incorrect as the mitochondria do not control the cell but rather produce energy. Choice C is incorrect as protein synthesis primarily occurs in the ribosomes. Choice D is incorrect as packaging waste for removal is a function associated with lysosomes, not mitochondria.
2. Where are B-lymphocytes produced?
- A. Thymus
- B. Red bone marrow
- C. Lymph nodes
- D. Spleen
Correct answer: B
Rationale: B-lymphocytes are produced in the red bone marrow. The red bone marrow is the primary site for B-cell development, where they mature before entering the circulation. The thymus is responsible for T-lymphocyte maturation, not B-lymphocytes. Lymph nodes and spleen play roles in immune responses but are not the primary sites for B-lymphocyte production.
3. What punctuation is needed in the following sentence to make it correct? The days seem long, but the nights seem even longer.
- A. Period
- B. Comma
- C. Colon
- D. Apostrophe
Correct answer: B
Rationale: The sentence needs a comma before the conjunction 'but' to correctly join the two independent clauses 'The days seem long' and 'the nights seem even longer.' This comma helps to create a clear separation between the contrasting ideas in the sentence. Choice A (Period) is incorrect because a period would create two separate sentences rather than connecting them. Choice C (Colon) is incorrect as colons are used to introduce lists, explanations, or quotations. Choice D (Apostrophe) is incorrect as it is not needed in this sentence.
4. If fifty-six kilograms of a radioactive substance has a half-life of 12 days, how many days will it take the substance to decay naturally to only 7 kilograms?
- A. 8
- B. 12
- C. 36
- D. 48
Correct answer: C
Rationale: To decay from 56 kg to 7 kg, the substance needs to go through 3 half-lives (56 kg ÷ 2 ÷ 2 ÷ 2 = 7 kg). Since each half-life is 12 days, the total time required is 12 days per half-life x 3 half-lives = 36 days. Choice A is incorrect because it does not consider the concept of half-lives. Choice B is incorrect because it represents the duration of a single half-life, not the total time required for the decay. Choice D is incorrect as it does not account for the multiple half-lives needed for the substance to decay from 56 kg to 7 kg.
5. How many liters are in 2,000 milliliters?
- A. 4 liters
- B. 1 liter
- C. 2 liters
- D. 4 liters
Correct answer: C
Rationale: The correct answer is 2 liters. There are 1,000 milliliters in a liter. Therefore, 2,000 milliliters is equal to 2 liters. Choice A is incorrect because it incorrectly doubles the conversion. Choice B is incorrect as it represents the amount in milliliters, not liters. Choice D is a duplicate of choice A, which is incorrect.
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