HESI A2
HESI A2 Biology 2024
1. 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.
2. What is the main component of blood plasma?
- A. Proteins
- B. Water
- C. Red Blood Cells
- D. Platelets
Correct answer: B
Rationale: The correct answer is B: Water. Blood plasma is composed mostly of water, which acts as a solvent for various nutrients and substances. Choices A, C, and D are incorrect. Proteins are indeed present in blood plasma but are not the main component. Red blood cells and platelets are cellular components of blood, not the main component of blood plasma.
3. The sum of all chemical reactions that occur in an organism is:
- A. product
- B. respiration
- C. metabolism
- D. synthesis
Correct answer: C
Rationale: Metabolism is the sum of all chemical reactions that occur within an organism to maintain life. It involves all the processes that break down molecules to release energy (catabolism) and build new molecules to support growth and maintenance (anabolism). Respiration refers specifically to the process of generating energy from the breakdown of glucose molecules. Synthesis is the creation of complex molecules from simpler ones. Therefore, metabolism is the most comprehensive term that encompasses all these processes within an organism.
4. Why do gardeners sometimes use salt to get rid of slugs?
- A. The salt moves from the exterior into the slug’s body.
- B. The salt causes water in the slug to move outward.
- C. The salt and slug slime merge to form a new compound.
- D. The salt’s corrosiveness breaks down the slug’s cell walls.
Correct answer: D
Rationale: Gardeners use salt to get rid of slugs because salt is corrosive and breaks down the slug's cell walls. When the slug comes into contact with salt, the salt draws moisture out of the slug's body, causing dehydration and ultimately leading to the slug's death. Choices A, B, and C are incorrect because the primary mechanism of salt in eliminating slugs is its corrosive action on the slug's body, not the movement of salt into the slug's body, outward movement of water in the slug, or merging with slug slime to form a new compound.
5. Which of the following is not a product of the Krebs cycle?
- A. carbon dioxide
- B. oxygen
- C. adenosine triphosphate (ATP)
- D. energy carriers
Correct answer: B
Rationale: The correct answer is B: oxygen. Oxygen is not a product of the Krebs cycle. During the Krebs cycle, carbon dioxide, adenosine triphosphate (ATP), and energy carriers like NADH and FADH2 are produced. Carbon dioxide is a byproduct of the cycle, ATP is a form of energy produced, and energy carriers play a crucial role in transferring energy within the cell. Therefore, oxygen is the only option that is not a product of the Krebs cycle, making it the correct answer.
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