HESI RN
Biology Practice Test
1. What is located on the rough endoplasmic reticulum?
- A. Microvilli
- B. Mitochondria
- C. Lysosomes
- D. Ribosomes
Correct answer: D
Rationale: The rough endoplasmic reticulum is studded with ribosomes, which are responsible for protein synthesis. Ribosomes are the correct answer because they are the organelles directly associated with the rough endoplasmic reticulum. Microvilli (choice A), mitochondria (choice B), and lysosomes (choice C) are not typically located on the rough endoplasmic reticulum. Microvilli are found on the surface of cells to increase surface area, mitochondria are the powerhouses of the cell responsible for energy production, and lysosomes are membrane-bound organelles containing digestive enzymes.
2. Which of the following is not true of mitosis?
- A. Mitosis produces daughter cells
- B. Mitosis has five main stages
- C. Mitosis can only be done by haploids
- D. Following mitosis, daughter cells are identical to parent cells
Correct answer: C
Rationale: The correct answer is C. Mitosis occurs in diploid cells and involves stages that result in the production of two identical daughter cells. Haploids do not undergo mitosis, as mitosis is a process specific to diploid cells. Choice A is true as mitosis does produce daughter cells. Choice B is incorrect as mitosis typically consists of four main stages: prophase, metaphase, anaphase, and telophase. Choice D is true, as one of the main outcomes of mitosis is the production of daughter cells that are genetically identical to the parent cell.
3. Protein synthesis begins with a process known as transcription. What is produced during this process?
- A. A codon
- B. A DNA helix
- C. A DNA strand
- D. An RNA strand
Correct answer: D
Rationale: The correct answer is D: An RNA strand. During transcription, the DNA template is used to produce an RNA strand, not a codon, DNA helix, or another DNA strand. A codon is a sequence of nucleotides that specifies a particular amino acid during translation, not produced during transcription. A DNA helix refers to the double-stranded structure of DNA, which is not produced during transcription. Another DNA strand is not produced during transcription since the process involves creating an RNA copy of a specific gene.
4. What is the most significant contributor to cellular function?
- A. Proteins
- B. Phospholipids
- C. Carbohydrates
- D. Fatty acids
Correct answer: A
Rationale: The correct answer is A: Proteins. Proteins are the most significant contributor to cellular function as they play crucial roles in almost all biological processes. They act as enzymes that catalyze reactions, are involved in cell signaling pathways, and provide structural support to cells. Phospholipids (Choice B), while important for cell membrane structure, do not have the same diverse functions as proteins in cellular processes. Carbohydrates (Choice C) primarily serve as an energy source and structural components but are not as versatile in cellular functions as proteins. Fatty acids (Choice D) are essential components of cell membranes and energy storage molecules but do not have the same broad range of functions as proteins in cellular processes.
5. What function does cholesterol, a phospholipid, serve within the cell membrane?
- A. It builds up fats to make the structure more flexible
- B. It allows protein channels to form
- C. It makes the structure very rigid and impermeable
- D. It stabilizes the membrane structure
Correct answer: D
Rationale: Cholesterol helps to maintain the fluidity and stability of the cell membrane by fitting between the phospholipid molecules. Choice A is incorrect because cholesterol does not build up fats in the cell membrane. Choice B is incorrect as protein channels are formed by proteins, not cholesterol. Choice C is incorrect as cholesterol actually helps regulate the fluidity of the membrane, making it less rigid and more permeable.
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