HESI A2
Biology HESI A2 Practice Exam
1. Bacillus subtilis may be described as ___________.
- A. spiral
- B. globular
- C. rod-shaped
- D. grape-like clusters
Correct answer: C
Rationale: Bacillus subtilis is a rod-shaped bacterium. Its name "Bacillus" refers to its rod-like shape, which is a characteristic feature of this bacteria.
2. How does an enzyme work on a chemical reaction that occurs in a substrate?
- A. An enzyme slows down the chemical reaction.
- B. An enzyme speeds up the chemical reaction.
- C. An enzyme has no effect on the chemical reaction.
- D. An enzyme stops most chemical reactions.
Correct answer: B
Rationale: Enzymes are biological catalysts that facilitate chemical reactions by lowering the activation energy required for the reaction to occur. This allows the reaction to proceed more quickly and efficiently. Enzymes do not change the overall outcome of the reaction, but they significantly increase the rate at which it takes place. Therefore, choice B, 'An enzyme speeds up the chemical reaction,' is the correct answer. Choices A, C, and D are incorrect because enzymes do not slow down, have no effect, or stop chemical reactions; instead, they accelerate the process by lowering the activation energy.
3. In which phase of mitosis do new nuclear membranes form around sets of chromosomes?
- A. Prophase
- B. Anaphase
- C. Telophase
- D. Interphase
Correct answer: C
Rationale: The correct answer is C, Telophase. During telophase, the final phase of mitosis, new nuclear membranes form around sets of chromosomes at the opposite poles of the cell. This process marks the completion of nuclear division in mitosis. Choices A, B, and D are incorrect because in prophase, chromosomes condense but nuclear membranes are not formed; in anaphase, chromosomes separate and move to opposite poles but no new nuclear membranes are formed; and in interphase, the cell prepares for division but nuclear membranes are not forming around sets of chromosomes.
4. Which of the following animals would have the least energy efficiency in nutrient consumption?
- A. Cow
- B. Caterpillar
- C. Coyote
- D. Cricket
Correct answer: A
Rationale: Cows are ruminant animals that have multiple stomachs and require large amounts of food to digest and convert into energy. They have lower energy efficiency compared to insects like caterpillars, coyotes, and crickets, which have more efficient nutrient consumption processes. The digestive system and metabolic functions of cows result in them having the least energy efficiency in nutrient consumption among the given choices. Caterpillars, coyotes, and crickets have more efficient nutrient consumption processes, making them more energy-efficient than cows.
5. How should a researcher test the hypothesis that radiation from cell phones is significant enough to raise the temperature of water in a test tube?
- A. Dial a cell phone that rests beside a test tube of water, let it ring for two minutes, and record the temperature of the water before and after the two-minute interval.
- B. Dial a cell phone that rests beside a test tube of water; let it ring for two, three, and four minutes; and record the temperature of the water before and after each interval.
- C. Use three different brands of cell phone; dial each as it rests beside its own test tube of water, let it ring for two minutes, and record the temperature of the water before and after the two-minute interval.
- D. Use three different brands of cell phone, dial each and let one ring for two minutes, one for three minutes, and one for four minutes; record the temperature of the water before and after each interval.
Correct answer: A
Rationale: To test the hypothesis that radiation from cell phones raises the temperature of water in a test tube, the most appropriate method is to dial a cell phone next to a test tube of water, let it ring for a consistent two-minute interval, and record the temperature before and after. Choice A is correct because it provides a controlled approach to isolate the impact of the phone's radiation on the water temperature. Choices B, C, and D introduce additional variables that could confound the results. Choice B varies the duration of exposure, making it difficult to attribute temperature changes specifically to the radiation. Choice C introduces the factor of different cell phone brands, which could introduce variability not related to radiation. Choice D also varies exposure times and introduces the factor of multiple phone brands, making it harder to determine the direct impact of cell phone radiation on water temperature. Therefore, choice A is the most suitable option for this experiment.
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