HESI A2
Biology HESI A2 Practice Exam
1. 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.
2. Which of the following are considered the most important molecules in biology?
- A. Carbohydrates, lipids, protein, and nucleic acids
- B. Carbohydrates, lipids, protein, and calcium
- C. Carbohydrates, lipids, protein, and sulfur
- D. Carbohydrates, lipids, protein, and iron
Correct answer: A
Rationale: The correct answer is A: Carbohydrates, lipids, protein, and nucleic acids are considered the most important molecules in biology. Carbohydrates are essential for providing energy, lipids for storing energy and forming cell membranes, proteins for various structural and functional roles, and nucleic acids (DNA and RNA) for storing genetic information. Choices B, C, and D are incorrect because while carbohydrates, lipids, and proteins are crucial biomolecules, calcium, sulfur, and iron are not considered among the most important molecules in biology.
3. 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.
4. Which bacteria are spherical in shape?
- A. Clostridia
- B. Bacilli
- C. Spirilla
- D. Cocci
Correct answer: D
Rationale: The correct answer is D, Cocci. Bacteria that are spherical in shape are known as cocci. They can be found in various arrangements such as clusters, chains, or pairs. Examples of cocci bacteria include Staphylococcus aureus and Streptococcus pneumoniae. Choice A, Clostridia, consists of rod-shaped bacteria. Choice B, Bacilli, refers to rod-shaped bacteria as well. Choice C, Spirilla, are spiral-shaped bacteria, not spherical.
5. Humans, or Homo sapiens, are part of the family ___________.
- A. Animalia
- B. Hominidae
- C. Mammalia
- D. Chordata
Correct answer: B
Rationale: Humans, or Homo sapiens, are part of the family Hominidae, which includes great apes such as gorillas, chimpanzees, and orangutans. This family belongs to the order Primates within the class Mammalia. Choice A (Animalia) refers to the animal kingdom, not the family of humans. Choice C (Mammalia) is the class to which the family Hominidae belongs, not the family itself. Choice D (Chordata) is the phylum to which humans and other animals with a notochord belong, not the specific family.
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