Nursing Elites

1. Not all cells in the pancreas secrete insulin because of the hormone somatostatin, which inhibits the release of insulin by all cells. What type of intercellular chemical signal does this illustrate?

• A. Autocrine
• B. Neuromodulator
• C. Paracrine
• D. Pheromone

Correct answer: C

Rationale: The correct answer is C: Paracrine. Somatostatin acts in a paracrine manner by inhibiting the release of insulin from nearby cells within the pancreas. Paracrine signaling involves the secretion of signals that act on neighboring cells, as seen in this scenario where somatostatin affects nearby pancreatic cells without entering the bloodstream or affecting distant cells. Autocrine signaling involves cells responding to substances they themselves release, which is not the case here. Neuromodulators are chemicals that modulate the activity of neurons, not directly related to this scenario. Pheromones are chemicals released into the environment to communicate with individuals of the same species, not relevant to the signaling within the pancreas.

2. What is the mass number of an element?

• A. The number of protons in an atom's nucleus.
• B. The number of neutrons in an atom's nucleus.
• C. The number of electrons in an atom's valence shell.
• D. The number of isotopes of an element.

Correct answer: B

Rationale: The mass number of an element represents the total number of protons and neutrons in an atom's nucleus. It specifically focuses on the number of neutrons in an atom's nucleus, which contributes to the overall mass of the atom. Therefore, the mass number is not solely determined by the number of protons, electrons, or isotopes. Choice A is incorrect because it refers to the atomic number, which is the number of protons in an atom's nucleus. Choice C is incorrect as the number of electrons in the valence shell is related to the atom's reactivity and bonding behavior, not the mass number. Choice D is incorrect because the mass number does not represent the number of isotopes of an element, but rather the sum of protons and neutrons in an atom's nucleus. Thus, option B, the number of neutrons in an atom's nucleus, is the correct choice.

3. Which of the following statements accurately characterizes the relationship between genes and chromosomes?

• A. Each gene contains multiple chromosomes.
• B. Each chromosome contains multiple genes.
• C. Genes and chromosomes are two different things referring to the same entity.
• D. Genes and chromosomes are not interchangeable terms and do not always occur in equal numbers.

Correct answer: B

Rationale: The correct answer is B: Each chromosome contains multiple genes. Genes, which are segments of DNA, are located on chromosomes and carry hereditary information. Chromosomes contain many genes, indicating that genes are part of the structure of chromosomes. Choice A is incorrect because genes do not contain chromosomes; rather, they are located on chromosomes. Choice C is incorrect as genes and chromosomes are distinct entities with different functions. Choice D is incorrect because genes and chromosomes are related but not in equal numbers; chromosomes contain multiple genes, but the number of genes can vary between chromosomes.

4. What property of matter explains why ice floats on water?

• A. Viscosity
• B. Density
• C. Buoyancy
• D. Surface tension

Correct answer: C

Rationale: The correct answer is C, buoyancy. Ice floats on water due to buoyancy, a property of matter. When water freezes into ice, it becomes less dense than liquid water, causing it to float. This phenomenon occurs because the molecules in ice are more spread out compared to liquid water, resulting in ice being less dense and able to float on the surface. Choice A, viscosity, is incorrect because viscosity refers to a fluid's resistance to flow, not its ability to float. Choice B, density, is incorrect because while ice being less dense than water is the reason it floats, this choice does not explain the specific property that causes this phenomenon. Choice D, surface tension, is incorrect as it pertains to the cohesive forces between molecules at the surface of a liquid, not the reason why ice floats on water.

5. Mesosomes are the internal extensions of which of the following?

• A. Capsule
• B. Cell membranes
• C. Cell wall
• D. Chromatin body

Correct answer: B

Rationale: Mesosomes are the internal extensions of the cell membrane, not the capsule, cell wall, or chromatin body. They play a crucial role in cell division and are essential for various cellular processes such as respiration and cell wall formation. Mesosomes are not associated with the capsule (choice A), cell wall (choice C), or chromatin body (choice D), making these options incorrect.

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