HESI A2
HESI A2 Biology Practice Test
1. Within the biological hierarchical system of organization, which of the following is least inclusive?
- A. phylum
- B. order
- C. kingdom
- D. species
Correct answer: D
Rationale: The correct answer is 'D: species.' In the biological hierarchical system of organization, a species is the least inclusive level. A species consists of organisms that share similar characteristics and can interbreed to produce fertile offspring. On the other hand, a phylum, order, and kingdom are more inclusive classifications that encompass multiple species. Phylum groups together related classes, order groups together related families, and kingdom groups together related phyla. Therefore, species is the least inclusive category within the biological hierarchical system.
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. What is necessary for active transport through a membrane to take place?
- A. Glucose
- B. Oxygen
- C. Sodium
- D. ATP
Correct answer: D
Rationale: Active transport through a membrane requires energy in the form of ATP (adenosine triphosphate). ATP provides the necessary energy for the transport proteins to move molecules against the concentration gradient, from an area of lower concentration to higher concentration. This process is essential for maintaining cellular functions and regulating the internal environment of a cell. Glucose, oxygen, and sodium are important molecules involved in various cellular processes, but they are not the primary energy source required for active transport across membranes. Therefore, the correct answer is ATP.
4. In an example of a male with hemophilia and a female carrier, what percentage of the offspring is predicted to be carriers only?
- A. 0%
- B. 25%
- C. 50%
- D. 100%
Correct answer: C
Rationale: In this scenario, the male offspring will inherit the X chromosome with the hemophilia gene from the mother, as males have one X chromosome inherited from their mother. The female offspring will inherit one normal X chromosome from the father and one X chromosome with the hemophilia gene from the mother, making them carriers of the hemophilia trait. Therefore, 50% of the offspring will be carriers only. Option A (0%) is incorrect as female offspring will inherit the X chromosome with the hemophilia gene from the mother. Option B (25%) is incorrect as the female offspring will not be unaffected. Option D (100%) is incorrect as not all offspring will be carriers, only the female offspring.
5. What is the second part of an organism’s scientific name?
- A. species
- B. phylum
- C. population
- D. kingdom
Correct answer: A
Rationale: The correct answer is 'species.' In binomial nomenclature, the second part of an organism's scientific name represents its species. The species name is a unique identifier within the genus and helps differentiate between different organisms within the same genus. Choices B, C, and D are incorrect. Phylum is a taxonomic rank higher than species, population refers to a group of organisms of the same species living in the same area, and kingdom is a taxonomic rank higher than genus.
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