Nursing Elites

1. Antigenic variation, a common strategy used by some viruses, allows them to:

• A. Produce toxins
• B. Evade the immune system
• C. Survive outside a host
• D. Replicate rapidly

Correct answer: B

Rationale: Antigenic variation is a strategy used by some viruses to evade the host's immune response. By constantly changing their surface antigens, viruses can avoid recognition and destruction by the immune system. This allows the virus to persist in the host and continue replicating, leading to prolonged infection and potential transmission to other hosts. Antigenic variation does not directly involve the production of toxins, survival outside a host, or rapid replication, making options A, C, and D incorrect in this context.

2. What are the constituents of an atomic nucleus?

• A. Electrons and protons only
• B. Protons and neutrons only
• C. Electrons, protons, and neutrons
• D. None of the above

Correct answer: B

Rationale: The correct answer is B: Protons and neutrons only. Electrons are located outside the nucleus in electron shells. Protons and neutrons are the subatomic particles found within the nucleus of an atom. Protons carry a positive charge, while neutrons are neutral. These particles contribute to the mass and stability of the nucleus. Choice A is incorrect because electrons are not part of the nucleus. Choice C is incorrect as electrons are not found within the nucleus, only protons and neutrons. Choice D is incorrect as protons and neutrons are indeed constituents of an atomic nucleus.

3. Which of the following statements about fungi is FALSE?

• A. They can be unicellular or multicellular
• B. They are all parasitic and cause disease in humans
• C. They play a vital role in decomposition and nutrient cycling
• D. Some are used in food production, like mushrooms

Correct answer: B

Rationale: A) This statement is true. Fungi can exist in both unicellular (yeast) and multicellular (molds and mushrooms) forms. B) This statement is false. While some fungi can be parasitic and cause diseases in humans, not all fungi exhibit this behavior. Many fungi are beneficial and play essential roles in ecosystems. C) This statement is true. Fungi are crucial for decomposition and nutrient cycling in ecosystems. They break down organic matter and recycle nutrients back into the environment. D) This statement is true. Some fungi, like mushrooms, are used in food production and are consumed by humans.

4. Which of the following statements best defines an organelle?

• A. Layer of polysaccharides outside the plasma membrane of cells.
• B. Abnormal infectious proteins.
• C. Specialized structures within a cell.
• D. Collection of tissues used to serve a specific function.

Correct answer: C

Rationale: The correct answer is C: 'Specialized structures within a cell.' An organelle is a specialized subunit within a cell that has a specific function. Organelles are membrane-bound structures found within the cytoplasm of eukaryotic cells, each performing distinct roles that contribute to the overall functioning of the cell. Choices A, B, and D are incorrect. Option A describes the glycocalyx, which is a layer of polysaccharides outside the plasma membrane of cells. Option B refers to prions, abnormal infectious proteins. Option D defines an organ, a collection of tissues used to serve a specific function, rather than an organelle within a cell.

5. What is the process by which the body reabsorbs water from the large intestine?

• A. Dehydration
• B. Osmosis
• C. Filtration
• D. Secretion

Correct answer: B

Rationale: Osmosis (Option B) is the correct process by which the body reabsorbs water from the large intestine. Osmosis is the movement of water across a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration. In the large intestine, water is reabsorbed through osmosis to maintain the body's fluid balance. Dehydration (Option A) refers to the condition of having insufficient water in the body, not the process of water reabsorption in the large intestine. Filtration (Option C) is a process where a liquid or gas passes through a filter to separate the components, not the primary mechanism for water reabsorption in the large intestine. Secretion (Option D) is the release of substances from cells, but it is not the process by which the body reabsorbs water from the large intestine.

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