HESI RN
Biology Practice Test
1. 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.
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. What is considered the main objective of the translation stage of protein synthesis?
- A. To produce amino acids
- B. To produce nucleotides
- C. To produce fatty acids
- D. To produce nucleic acids
Correct answer: A
Rationale: The correct answer is A: To produce amino acids. During the translation stage of protein synthesis, the mRNA is decoded to assemble a specific sequence of amino acids. These amino acids then fold into a functional protein. Choices B, C, and D are incorrect because the translation stage specifically deals with the production of amino acids, not nucleotides, fatty acids, or nucleic acids.
4. Proteins are polymers of 20 molecules called:
- A. Amino acids
- B. Phospholipids
- C. Carbohydrates
- D. Fatty acids
Correct answer: A
Rationale: Proteins are indeed polymers made up of amino acids. Amino acids are the building blocks of proteins, where each protein has a unique sequence of amino acids that determines its structure and function. Phospholipids, carbohydrates, and fatty acids are not molecules that make up proteins. Phospholipids are the main components of cell membranes, carbohydrates are sugars used for energy and structural purposes, and fatty acids are building blocks of lipids.
5. 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.
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