HESI RN
Biology Test
1. What percentage of the parents' offspring is predicted to have a cleft chin if one parent carries the recessive gene for a cleft chin (c) while the other parent does not?
- A. 25%
- B. 50%
- C. 0%
- D. 75%
Correct answer: C
Rationale: The correct answer is C (0%). If one parent carries the recessive gene for a cleft chin while the other parent does not carry it, none of their offspring is predicted to have a cleft chin. This is because the cleft chin trait is recessive, so for an offspring to express this trait, they would need to inherit the gene from both parents. In this scenario, none of the offspring will inherit the recessive gene from both parents, so the percentage of offspring predicted to have a cleft chin is 0%. Choices A, B, and D are incorrect because in this situation, the offspring will not express the cleft chin phenotype, although they could be carriers of the recessive gene.
2. What is the difference between DNA and RNA?
- A. RNA has an extra Phosphate group
- B. DNA has one less oxygen than RNA
- C. RNA has one less oxygen than DNA
- D. DNA has an extra sugar molecule
Correct answer: B
Rationale: The correct answer is B. DNA has one less oxygen atom in its sugar molecule (deoxyribose) compared to RNA, which has a ribose sugar. Choice A is incorrect because RNA does not have an extra phosphate group. Choice C is incorrect as RNA actually has one more oxygen atom than DNA. Choice D is incorrect as DNA and RNA have different sugar molecules, with DNA having deoxyribose and RNA having ribose.
3. Which of the following statements is most accurate regarding the transcription of DNA?
- A. RNA uses reverse transcriptase to make mRNA
- B. DNA uses mRNA to produce tRNA
- C. RNA creates a duplicate copy of DNA
- D. RNA copies DNA to produce mRNA
Correct answer: D
Rationale: The correct answer is D. During transcription, RNA copies DNA to produce mRNA, which carries the genetic information from DNA to the ribosomes for protein synthesis. Choice A is incorrect because reverse transcriptase is not involved in the transcription of DNA. Choice B is incorrect as DNA does not use mRNA to produce tRNA; tRNA is produced through a different process. Choice C is incorrect as RNA does not create a duplicate copy of DNA during transcription; it synthesizes mRNA by copying the DNA template.
4. Phagocytes in the immune system are responsible for the biological action of which of the following?
- A. Secreting
- B. Consuming
- C. Altering
- D. Building
Correct answer: B
Rationale: The correct answer is B: Consuming. Phagocytes are cells that engulf and digest pathogens, dead cells, and other harmful particles, playing a crucial role in the immune system's defense. Phagocytes do not secrete substances, alter particles, or build structures; their primary function is to consume and eliminate harmful entities.
5. The bilayer of the cellular membrane consists of phospholipids with all except which of the following scattered throughout?
- A. Nucleic acids
- B. Cholesterol
- C. Proteins
- D. Glycoproteins
Correct answer: A
Rationale: The cellular membrane is composed of a phospholipid bilayer with cholesterol, proteins, and glycoproteins distributed throughout. Nucleic acids are not found within the cellular membrane. Cholesterol helps maintain membrane fluidity, while proteins and glycoproteins play important roles in cell signaling, transport, and structural support.
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