HESI RN
Biology Practice Test
1. Which of the following organelles is the site of cellular respiration?
- A. Nucleus
- B. Mitochondria
- C. Lysosomes
- D. Ribosomes
Correct answer: B
Rationale: The correct answer is B: Mitochondria. Mitochondria are known as the powerhouse of the cell because they generate most of the cell's supply of ATP through cellular respiration. The other organelles listed, such as the nucleus (choice A), lysosomes (choice C), and ribosomes (choice D), do not play a direct role in cellular respiration. The nucleus contains genetic material, lysosomes are involved in digestion and waste removal, and ribosomes are responsible for protein synthesis.
2. Which of the following is a group of three RNA nucleotides?
- A. A stop codon
- B. A codon
- C. An anticodon
- D. tRNA
Correct answer: B
Rationale: The correct answer is B - A codon. A codon is a sequence of three RNA nucleotides that specifies a particular amino acid or a stop signal during protein synthesis. Choice A, a stop codon, is a sequence of three nucleotides that signals the termination of protein synthesis. Choice C, an anticodon, is a group of three nucleotides found in tRNA that pairs with the complementary codon in mRNA. Choice D, tRNA, stands for transfer RNA, which is a type of RNA that carries amino acids to the ribosome during protein synthesis.
3. Which of the following best describes phenotype?
- A. The hereditary potentials and limitations of an individual
- B. The genetic makeup of an individual organism
- C. The entire complex of genes inherited from both parents
- D. All the observable characteristics of an organism
Correct answer: D
Rationale: The correct answer is D: 'All the observable characteristics of an organism.' Phenotype refers to all the observable characteristics of an organism, such as physical appearance, behavior, and other traits, which result from the interaction of its genotype with the environment. Choice A is incorrect because it describes genotype. Choice B is incorrect as it defines genotype, not phenotype. Choice C is incorrect as it refers to the genotype, the genetic information inherited from both parents, rather than the observable traits.
4. In which of the following does cellular respiration take place?
- A. Golgi apparatus
- B. Mitochondrion
- C. Chloroplast
- D. Ribosome
Correct answer: B
Rationale: The correct answer is B, Mitochondrion. Cellular respiration occurs in the mitochondria, where glucose is converted into energy through a series of metabolic processes. Choice A, Golgi apparatus, is incorrect as it is involved in modifying, sorting, and packaging proteins. Choice C, Chloroplast, is incorrect as it is the site of photosynthesis in plant cells, not cellular respiration. Choice D, Ribosome, is incorrect as it is responsible for protein synthesis, not energy production through cellular respiration.
5. Protein synthesis begins with a process known as transcription. Where does this process occur?
- A. In the cytoplasm
- B. In the nuclear envelope
- C. In the ribosome unit
- D. In the nucleus
Correct answer: D
Rationale: The correct answer is D: In the nucleus. Transcription, the initial step of protein synthesis, takes place in the nucleus where DNA is transcribed into mRNA. This mRNA then leaves the nucleus and enters the cytoplasm where translation occurs on the ribosomes. Choices A, B, and C are incorrect because transcription specifically occurs in the nucleus, not in the cytoplasm, nuclear envelope, or ribosome unit.
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