Nursing Elites

1. What is the primary function of the cell membrane?

• A. To provide structural support for the cell
• B. To transport substances in and out of the cell
• C. To synthesize proteins and lipids
• D. To store genetic material

Correct answer: B

Rationale: The primary function of the cell membrane, also known as the plasma membrane, is to regulate the movement of substances in and out of the cell. It acts as a selectively permeable barrier, allowing specific molecules to pass through while blocking others. This role is crucial for maintaining the internal environment of the cell by enabling essential nutrients to enter and waste products to exit. While the cell membrane provides some structural support for the cell, its main function is substance transport. Protein and lipid synthesis predominantly occur in organelles like the endoplasmic reticulum and Golgi apparatus, and storing genetic material is the nucleus's responsibility. Therefore, choices C (To synthesize proteins and lipids) and D (To store genetic material) are incorrect as these functions are carried out by other cell organelles, not the cell membrane.

2. What causes varicose veins to occur?

• A. Atherosclerosis.
• B. Incompetent valves.
• C. Loss of skin turgor.
• D. Loss of blood vessel elasticity.

Correct answer: B

Rationale: Varicose veins occur when the valves within the veins become incompetent, leading to blood pooling in the veins instead of being efficiently pumped back to the heart. This causes the veins to become enlarged, twisted, and visible under the skin. Factors such as genetics, aging, pregnancy, and prolonged standing or sitting can contribute to the development of incompetent valves and the resulting varicose veins. Atherosclerosis is the buildup of plaque in arteries, not veins, and does not directly cause varicose veins. Loss of skin turgor is related to skin elasticity and not a direct cause of varicose veins. Loss of blood vessel elasticity is a general term and does not specifically address the mechanism behind varicose veins, which is primarily due to incompetent valves.

3. Melatonin is a hormone produced by the pineal gland. What is its primary function?

• A. Regulate blood pressure
• B. Stimulate the digestive system
• C. Control sleep-wake cycles
• D. Maintain bone density

Correct answer: C

Rationale: Melatonin is primarily known for its role in controlling sleep-wake cycles. It is produced by the pineal gland in response to darkness, helping signal the body that it is time to sleep. Melatonin levels typically rise in the evening and stay elevated throughout the night, promoting sleep. Choices A, B, and D are incorrect as melatonin's primary function is not to regulate blood pressure, stimulate the digestive system, or maintain bone density. While melatonin may have some indirect effects on these functions, its main role lies in regulating the circadian rhythm and promoting a restful sleep cycle.

4. Which type of carbohydrate is the main component of the cell wall in plant cells?

• A. Starch
• B. Glucose
• C. Cellulose
• D. Chitin

Correct answer: C

Rationale: The correct answer is 'Cellulose.' Cellulose is the main component of the cell wall in plant cells, providing structural support and rigidity. Starch, while a carbohydrate, is a storage form of glucose in plants and not a component of the cell wall. Glucose is a simple sugar that can be used as an energy source but is not the main component of the cell wall. Chitin is a structural carbohydrate found in the exoskeleton of arthropods and fungi, not in plant cell walls.

5. What is the primary function of ribosomes in the cell?

• A. To synthesize lipids and other cellular components
• B. To package and transport proteins
• C. To break down macromolecules
• D. To translate mRNA into proteins

Correct answer: D

Rationale: Ribosomes are cellular organelles responsible for protein synthesis. They read the genetic information encoded in messenger RNA (mRNA) and use this information to assemble amino acids into a specific sequence, forming a protein. This process is known as translation and is essential for the production of proteins that carry out various functions in the cell. Options A, B, and C are incorrect as they do not accurately describe the primary function of ribosomes. Choice A is incorrect because the synthesis of lipids and other cellular components is not the primary function of ribosomes. Choice B is incorrect as packaging and transporting proteins are functions typically associated with the endoplasmic reticulum and Golgi apparatus. Choice C is incorrect because ribosomes do not break down macromolecules; instead, they are involved in building proteins from amino acids.

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