HESI RN
Biology Practice Test
1. 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.
2. 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.
3. What is the primary method of asexual reproduction used by most bacteria?
- A. Meiosis
- B. Mitosis
- C. Binary fission
- D. Interphase
Correct answer: C
Rationale: The correct answer is C: Binary fission. This is the main process through which most bacteria reproduce asexually. During binary fission, a single cell divides into two identical cells, each containing a copy of the genetic material. Choices A and B, meiosis and mitosis, are processes involved in sexual reproduction and are not used by bacteria for asexual reproduction. Choice D, interphase, is a stage of the cell cycle where the cell prepares for division and is not a method of reproduction.
4. Which of the following is responsible for the synthesis of carbohydrates, lipids, and steroid hormones?
- A. Smooth endoplasmic reticulum (ER)
- B. Rough endoplasmic reticulum (ER)
- C. Golgi apparatus
- D. Ribosomes
Correct answer: A
Rationale: The smooth endoplasmic reticulum (ER) is the correct answer. It is responsible for the synthesis of lipids, including steroids, and also plays a role in carbohydrate metabolism. The rough endoplasmic reticulum (ER) is involved in protein synthesis and processing, not lipid or carbohydrate synthesis. The Golgi apparatus is responsible for modifying, sorting, and packaging of proteins and lipids, but not for their synthesis. Ribosomes are the cellular organelles responsible for protein synthesis, not lipid or carbohydrate synthesis.
5. What cell structure is responsible for efficiently packaging DNA into a small volume to fit into the nucleus of a cell and protect the DNA structure and sequence?
- A. Golgi apparatus
- B. Chromatin
- C. Smooth endoplasmic reticulum
- D. Mitochondria
Correct answer: B
Rationale: Chromatin is the correct answer. Chromatin is responsible for packaging DNA into a more compact, dense structure to fit into the nucleus and protect the DNA. The Golgi apparatus is involved in processing and packaging proteins, not DNA. Smooth endoplasmic reticulum is involved in lipid metabolism and detoxification. Mitochondria are known as the powerhouse of the cell responsible for energy production, not DNA packaging.
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