HESI A2
HESI A2 Biology 2024
1. Patient A, who weighs 68 kilograms, steps onto a scale 20 times. The scale consistently weighs Patient A as 75 kilograms. What is true of the measurement?
- A. It is valid, but not reliable.
- B. It is reliable, but not valid.
- C. It is both valid and reliable.
- D. It is neither reliable nor valid.
Correct answer: B
Rationale: The correct answer is B: 'It is reliable, but not valid.' The measurement is reliable because it consistently provides the same result (75 kg). However, it is not valid because it does not accurately reflect the true weight of Patient A (68 kg). Choice A is incorrect because if the scale consistently shows the same weight (75 kg), it is reliable. Choice C is incorrect because although the scale is consistent, the measurement does not reflect the true weight, making it not valid. Choice D is incorrect as the measurement is reliable but lacks validity.
2. What happens during anaphase?
- A. Chromosomes move to opposite ends of the spindle.
- B. Nuclear membrane and nucleoli disintegrate.
- C. Chromatids line up at the center of the spindle.
- D. Nuclear membrane and nucleoli form.
Correct answer: A
Rationale: During anaphase, the sister chromatids, joined at the centromere, separate and move towards opposite ends of the spindle apparatus. This movement ensures that each daughter cell receives an identical set of chromosomes. Choice B is incorrect as the disintegration of the nuclear membrane and nucleoli occurs during prophase. Choice C is incorrect as chromatids align at the center of the spindle during metaphase, not anaphase. Choice D is incorrect as the formation of the nuclear membrane and nucleoli occurs during telophase, not anaphase.
3. Whose energy efficiency is greater?
- A. Herbivore
- B. Carnivore
- C. Omnivore
- D. Decomposer
Correct answer: D
Rationale: Decomposers have the greatest efficiency of energy among the given options. Decomposers break down organic matter, such as dead plants and animals, into simpler substances through the process of decomposition. This breakdown process results in the release of nutrients back into the ecosystem, making energy more readily available for other organisms to use. In contrast, herbivores, carnivores, and omnivores all derive their energy from the consumption of other living organisms, making their energy efficiency lower than that of decomposers. Herbivores consume plants for energy, which involves energy loss due to inefficiencies in converting plant matter into usable energy. Carnivores consume herbivores or other carnivores, leading to further energy loss through each trophic level. Omnivores consume both plant and animal matter, but their energy efficiency is still lower than decomposers because of the energy loss associated with consuming living organisms. Decomposers play a crucial role in recycling nutrients and energy in ecosystems, making them highly efficient in the utilization of energy.
4. How should a researcher test the hypothesis that practicing yoga reduces blood pressure?
- A. Record the blood pressure of one male and one female participant before and after participating in a yoga class.
- B. Divide 30 female participants into two groups with similar average blood pressure; test each participant’s blood pressure after participating in a yoga class.
- C. Divide 30 female participants into two groups with similar average blood pressure; have one group watch television for an hour while the other takes a yoga class, record each participant’s blood pressure after the hour. Repeat daily for two weeks.
- D. Start with 15 men and 15 women; have the men watch television for an hour while the women take a yoga class, record each participant’s blood pressure after the hour. Reverse, having the men take a yoga class while the women watch television.
Correct answer: B
Rationale: Option B is the most appropriate way to test the hypothesis that practicing yoga reduces blood pressure. By dividing 30 female participants into two groups with similar average blood pressure levels and testing each participant's blood pressure after participating in a yoga class, the researcher can effectively evaluate the impact of yoga on blood pressure. This design allows for a comparison between the two groups, helping to isolate the effects of yoga practice on blood pressure. Option A only involves one male and one female participant, which may not provide a representative sample. Option C introduces an additional variable of watching television, which could confound the results. Option D lacks consistency in the experimental design by switching the activities between men and women, making it difficult to attribute any observed changes solely to yoga practice.
5. From which component do RNA and DNA derive their names?
- A. From the sugar each contains
- B. From the structure of their nucleotides
- C. From the information they transfer
- D. From their formative processes
Correct answer: A
Rationale: RNA and DNA derive their names from the sugar each contains. RNA stands for Ribonucleic Acid, with 'ribo' indicating the ribose sugar in its structure. DNA stands for Deoxyribonucleic Acid, with 'deoxyribo' referring to the deoxyribose sugar in its structure. The sugars in RNA and DNA molecules distinguish them and are the basis for their names. Choices B, C, and D are incorrect as they do not accurately explain how RNA and DNA derive their names.
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