prokaryotic cells lack which of the following

HESI RN

Biology Practice Test

1. Which of the following do prokaryotic cells lack?

A. A cell membrane
B. Genetic material
C. Cytoplasm
D. Membrane-bound organelles

Correct answer: D

Rationale: The correct answer is D: Prokaryotic cells lack membrane-bound organelles, such as mitochondria or a nucleus, distinguishing them from eukaryotic cells. Prokaryotic cells do have genetic material, a cell membrane, and cytoplasm. Choice A is incorrect because prokaryotic cells do have a cell membrane, which is essential for maintaining cell structure and regulating what enters and exits the cell. Choice B is incorrect because prokaryotic cells contain genetic material, typically in the form of a single circular chromosome. Choice C is incorrect because prokaryotic cells have cytoplasm, where various cellular activities take place.

2. The bilayer of the cellular membrane consists of phospholipids with all except which of the following scattered throughout?

A. Nucleic acids
B. Cholesterol
C. Proteins
D. Glycoproteins

Correct answer: A

Rationale: The cellular membrane is composed of a phospholipid bilayer with cholesterol, proteins, and glycoproteins distributed throughout. Nucleic acids are not found within the cellular membrane. Cholesterol helps maintain membrane fluidity, while proteins and glycoproteins play important roles in cell signaling, transport, and structural support.

3. 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.

4. Which of the following molecules acts as the genetic code's messenger?

A. RNA
B. Proteins
C. DNA
D. Carbohydrates

Correct answer: A

Rationale: The correct answer is RNA. RNA, particularly mRNA, serves as the messenger that carries genetic information from DNA to the ribosome, where proteins are synthesized. Proteins (choice B) are not the genetic code's messenger; they are synthesized based on the information carried by RNA. DNA (choice C) stores the genetic information but does not directly act as the messenger. Carbohydrates (choice D) are not involved in transmitting genetic information.

5. What are the two primary products of photosynthesis?

A. Sugar and oxygen
B. Sugar and carbon dioxide
C. Oxygen and nitrogen
D. Nitrogen and carbon dioxide

Correct answer: A

Rationale: The correct answer is A: Sugar and oxygen. During photosynthesis, plants convert carbon dioxide and water into glucose (sugar) and oxygen using sunlight. Choice B, 'Sugar and carbon dioxide,' is incorrect because carbon dioxide is one of the reactants, not a product. Choice C, 'Oxygen and nitrogen,' is incorrect as nitrogen is not a direct product of photosynthesis. Choice D, 'Nitrogen and carbon dioxide,' is incorrect because nitrogen is not a product of photosynthesis, and carbon dioxide is a reactant.