HESI A2
Biology HESI A2 Practice Exam
1. As cattle graze, cattle egrets consume the insects they stir up. This is an example of ___________.
- A. Mutualism
- B. Parasitism
- C. Commensalism
- D. Competition
Correct answer: C
Rationale: Commensalism is a relationship between two species in which one benefits without affecting the other species. In this scenario, the cattle egrets benefit from the insects stirred up by cattle while the cattle are not significantly impacted by the presence of the egrets. The egrets obtain food easily, and the cattle are neither harmed nor helped by the egrets' presence, making it an example of commensalism. Mutualism involves both species benefiting, parasitism involves one species benefiting at the expense of the other, and competition involves both species being negatively affected by their interactions, none of which apply to the relationship between cattle and cattle egrets in this context.
2. Which is not part of a nucleic acid?
- A. Sulfate
- B. Phosphate
- C. Carbon
- D. Nitrogen
Correct answer: A
Rationale: Sulfate is not part of a nucleic acid. Nucleic acids, such as DNA and RNA, are composed of nucleotide units, which consist of a phosphate group, a sugar molecule (ribose in RNA and deoxyribose in DNA), and a nitrogenous base. Carbon and nitrogen are essential elements found in nucleic acids, while sulfate is not a component of nucleic acid structure. Therefore, the correct answer is A: Sulfate.
3. 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.
4. What is the result of adding 7/8 + 9/10 + 6/5?
- A. 3 & 39/40
- B. 3 & 22/23
- C. 22/23
- D. 30
Correct answer: A
Rationale: To add fractions, you need to find a common denominator. The common denominator for 8, 10, and 5 is 40. Then, convert each fraction: 7/8 = 35/40, 9/10 = 36/40, and 6/5 = 24/40. Now, add the fractions: 35/40 + 36/40 + 24/40 = 95/40, which simplifies to 2 15/40 or 2 3/8. Therefore, 7/8 + 9/10 + 6/5 = 3 & 39/40. Choice B is incorrect because it does not represent the correct addition of the fractions. Choice C is incorrect as it does not account for the whole number part. Choice D is incorrect as it is not the sum of the fractions and whole numbers.
5. What word is best to substitute for the underlined words in the following sentence? You can hear the nurses’ laughter all the way down the hallway.
- A. his
- B. hers
- C. them
- D. their
Correct answer: D
Rationale: The phrase 'the nurses’ laughter' indicates possession by the nurses, a plural subject. Therefore, the appropriate possessive pronoun to use in this context is 'their,' which correctly reflects possession by multiple nurses. Choice A ('his') is singular and refers to a male subject, not suitable for a group of nurses. Choice B ('hers') is singular and refers to a female subject, not suitable for a group of nurses. Choice C ('them') is a pronoun used for a group of people, but it doesn't indicate possession as required in the sentence.
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