HESI A2
HESI A2 Biology 2024
1. 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.
2. Why is polarity the most important characteristic of water?
- A. the results of the polarity are hydrogen bonding, a high specific heat value, and its versatile solvent properties
- B. the results of the polarity are covalent bonding, a low specific heat value, and its versatile solvent properties
- C. the results of the polarity are ionic bonding, a high specific heat value, and its versatile solvent properties
- D. the results of the polarity are hydrogen bonding, a low specific heat value, and its versatile solvent properties
Correct answer: A
Rationale: Polarity is the most important characteristic of water because it results in hydrogen bonding, a high specific heat value, and its versatile solvent properties. These unique properties enable water to form hydrogen bonds with other substances, resist temperature changes, and dissolve a wide variety of solutes, making it essential for life processes. Choice B is incorrect because water exhibits hydrogen bonding, not covalent bonding. Choice C is incorrect as water does not form ionic bonds. Choice D is incorrect because water has a high, not low, specific heat value, which is vital for its role in temperature regulation.
3. 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.
4. Which of these molecules contains glucose?
- A. Proteins
- B. Lipids
- C. Nucleic acids
- D. Carbohydrates
Correct answer: D
Rationale: Glucose is a type of simple sugar and is classified as a carbohydrate. It is commonly found in various carbohydrate-containing foods such as fruits, vegetables, grains, and sugary snacks. Therefore, the molecule containing glucose would be a carbohydrate, making choice D the correct answer. Proteins (choice A) are made up of amino acids, lipids (choice B) are fats, and nucleic acids (choice C) are DNA and RNA, none of which contain glucose.
5. The two catabolic pathways that lead to cellular energy production are:
- A. fermentation and protein synthesis
- B. cellular respiration and glycolysis
- C. fermentation and glycolysis
- D. cellular respiration and fermentation
Correct answer: D
Rationale: The correct answer is D: cellular respiration and fermentation. Cellular respiration involves the breakdown of glucose in the presence of oxygen to produce ATP, which is the primary source of energy for cells. Fermentation, on the other hand, occurs in the absence of oxygen and produces ATP through glycolysis followed by specific fermentation pathways. Choices A, B, and C are incorrect. Protein synthesis is a biosynthetic process, not a catabolic pathway for energy production. Glycolysis is a common step in both cellular respiration and fermentation, so it is not a pair of distinct catabolic pathways. Therefore, the most accurate pairing of catabolic pathways for cellular energy production is cellular respiration and fermentation.
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