what function does cholesterol a phospholipid serve within the cell membrane

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 correctly identifies the two types of cells?

A. Mitosis and meiosis
B. Mitochondrion and chloroplast
C. Genotype and phenotype
D. Prokaryotic and eukaryotic

Correct answer: D

Rationale: The correct answer is D: Prokaryotic and eukaryotic. Cells are classified into two major types: prokaryotic, which lack a nucleus, and eukaryotic, which have a defined nucleus and other membrane-bound organelles. Choice A, mitosis and meiosis, refers to cell division processes. Choice B, mitochondrion and chloroplast, are cell organelles involved in energy production and photosynthesis, respectively. Choice C, genotype and phenotype, relate to genetic characteristics and physical traits, not cell types.

3. During photosynthesis in green plants, light energy is captured and used to convert all except which of the following into oxygen and energy-rich organic compounds?

A. Minerals
B. Water
C. Carbon dioxide
D. Metals

Correct answer: D

Rationale: During photosynthesis in green plants, light energy is utilized to convert water and carbon dioxide into oxygen and energy-rich organic compounds like glucose. Minerals play a role in plant growth but are not directly converted during photosynthesis. Metals are not part of the photosynthesis process, making them the correct answer. Therefore, the correct choice is D. Choices A, B, and C are incorrect as minerals, water, and carbon dioxide are involved in the photosynthesis process.

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. Which of the following organelles is known as the cell's digestion center?

A. Chloroplasts
B. Mitochondria
C. Lysosomes
D. Ribosomes

Correct answer: C

Rationale: The correct answer is C: Lysosomes. Lysosomes contain enzymes that break down waste materials and cellular debris within the cell, making them the cell's digestion center. Choice A, Chloroplasts, are responsible for photosynthesis. Choice B, Mitochondria, are the powerhouse of the cell, generating energy. Choice D, Ribosomes, are involved in protein synthesis. Therefore, Lysosomes are specifically known for their role in digestion within the cell.