Nursing Elites

1. Why do cells need to use exocytosis?

• A. To obtain energy
• B. To defend against invaders
• C. To remove waste products
• D. To undergo division

Correct answer: C

Rationale: Cells need to use exocytosis to remove waste products from the cell. Exocytosis is a process where cells release molecules or substances outside the cell by fusing vesicles with the cell membrane. This process is crucial for maintaining cellular homeostasis by efficiently eliminating waste materials. Choices A, B, and D are incorrect because exocytosis is specifically involved in the expulsion of molecules, not for obtaining energy, defending against invaders, or cell division.

2. Which is not part of a nucleic acid?

• A. Sulfate
• B. Phosphate
• C. Carbon
• D. Nitrogen

Correct answer: A

Rationale: Sulfate is not part of a nucleic acid. Nucleic acids, such as DNA and RNA, are composed of nucleotide units, which consist of a phosphate group, a sugar molecule (ribose in RNA and deoxyribose in DNA), and a nitrogenous base. Carbon and nitrogen are essential elements found in nucleic acids, while sulfate is not a component of nucleic acid structure. Therefore, the correct answer is A: Sulfate.

3. In a strand of DNA, you would expect to see adenine paired with ___________.

• A. cytosine
• B. uracil
• C. thymine
• D. guanine

Correct answer: C

Rationale: In a strand of DNA, adenine always pairs with thymine through two hydrogen bonds. This pairing is a fundamental aspect of DNA structure, where adenine and thymine complement each other in the double helix. Choice A (cytosine) is incorrect because adenine does not pair with cytosine in DNA. Choice B (uracil) is incorrect as uracil is found in RNA, not DNA. Choice D (guanine) is incorrect as guanine pairs with cytosine, not adenine, in DNA.

4. Tonicity refers to the movement of:

• A. Water
• B. Solute
• C. Cells
• D. None of the above

Correct answer: A

Rationale: Tonicity refers to the movement of water across a membrane in response to differences in solute concentration. In a hypertonic solution, where there is a higher concentration of solutes outside the cell, water will move out of the cell to try to reach equilibrium. In a hypotonic solution, where there is a lower concentration of solutes outside the cell, water will move into the cell to balance the concentrations. Cells and solutes themselves do not actively move in response to tonicity; it is the movement of water that helps achieve equilibrium. Therefore, the correct answer is water (Choice A). Choices B, C, and D are incorrect as tonicity specifically refers to water movement and not the movement of solutes, cells, or none of the above.

5. What is the composition of the plasma membrane?

• A. Proteins
• B. Lipids
• C. Carbohydrates
• D. Nucleotides

Correct answer: B

Rationale: The plasma membrane is composed of lipids, proteins, and carbohydrates. While proteins are an essential component of the plasma membrane, it is not the only constituent. Carbohydrates and lipids also play crucial roles in the structure and function of the plasma membrane. Nucleotides are not part of the primary structural components of the plasma membrane, making this choice incorrect.

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