HESI RN
Biology Practice Test
1. Which of the following processes produces nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FADH2) for the electron transport chain during cellular respiration?
- A. Electron transport chain
- B. Glycolysis
- C. Citric acid cycle (the Krebs cycle)
- D. None of these
Correct answer: C
Rationale: The correct answer is C, the citric acid cycle (the Krebs cycle). This cycle generates NADH and FADH2, which play a crucial role in providing electrons to the electron transport chain during cellular respiration. Choice A, the electron transport chain itself, is where NADH and FADH2 donate their electrons, not where they are produced. Choice B, glycolysis, produces NADH but not FADH2. Choice D, 'None of these,' is incorrect as the citric acid cycle specifically produces NADH and FADH2.
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. At the beginning of meiosis, how many chromosomes does the diploid parent cell have?
- A. 23
- B. 24
- C. 46
- D. 54
Correct answer: C
Rationale: The correct answer is C: 46. At the start of meiosis, the diploid parent cell contains 46 chromosomes. During meiosis, the number of chromosomes is halved, resulting in each gamete having 23 chromosomes. Choice A (23) is incorrect because that is the number of chromosomes in a human gamete, not the parent cell. Choice B (24) and Choice D (54) are also incorrect as they do not reflect the correct number of chromosomes in a diploid parent cell at the beginning of meiosis.
4. During which stage of mitosis does the nuclear envelope begin to disappear and the chromosomes start attaching to the spindle forming along the cell's axis?
- A. Prometaphase
- B. Metaphase
- C. Anaphase
- D. Prophase
Correct answer: A
Rationale: The correct answer is A, Prometaphase. During prometaphase, the nuclear envelope disintegrates, and chromosomes start attaching to spindle fibers. In metaphase, chromosomes align in the middle of the cell. Anaphase is characterized by the separation of sister chromatids, and prophase involves the condensation of chromosomes and the beginning of spindle formation.
5. Which of the following terms is used to represent two alleles that are the same type?
- A. Homosynchronous
- B. Hypersynchronous
- C. Heterozygous
- D. Homozygous
Correct answer: D
Rationale: The correct answer is D, 'Homozygous.' Homozygous refers to having two identical alleles for a particular gene. In this context, 'Homosynchronous' (choice A) is not a recognized genetic term. 'Hypersynchronous' (choice B) is not a term used in genetics. 'Heterozygous' (choice C) refers to having two different alleles for a particular gene, which is the opposite of homozygous.
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