Nursing Elites

1. What does half-life refer to?

• A. Radioactive intensity to completely disappear
• B. The number of neutrons in a nucleus to double
• C. The number of protons in a nucleus to change
• D. An isotope to decay by half of its initial quantity

Correct answer: D

Rationale: Half-life refers to the time it takes for half of the radioactive atoms in a sample to decay. This means that after one half-life, half of the initial quantity of the radioactive substance will have decayed. Choice A is incorrect because radioactive intensity doesn't completely disappear during half-life. Choice B is incorrect as half-life doesn't refer to the number of neutrons doubling. Choice C is incorrect as half-life doesn't relate to the number of protons changing.

2. What is the role of RNA interference in silencing genes?

• A. Increases protein production
• B. Promotes gene mutation
• C. Inhibits the expression of specific genes
• D. Repairs damaged DNA

Correct answer: C

Rationale: RNA interference (RNAi) is a biological process that involves the silencing of gene expression by inhibiting the translation of mRNA or by degrading mRNA molecules. This mechanism plays a crucial role in regulating gene expression and can be used to selectively silence specific genes. By interfering with the expression of specific genes, RNAi can downregulate protein production from those genes. Therefore, option C, 'Inhibits the expression of specific genes,' is the correct role of RNA interference in silencing genes. Options A, B, and D are incorrect because RNA interference does not increase protein production, promote gene mutation, or repair damaged DNA; its primary function is to inhibit gene expression by degrading or interfering with mRNA.

3. Which property of a substance measures the amount of matter per unit volume?

• A. Density
• B. Mass
• C. Weight
• D. Volume

Correct answer: A

Rationale: Density is the property of a substance that measures the amount of matter per unit volume. It is calculated by dividing the mass of the substance by its volume. Mass refers to the amount of matter in an object, weight is the force of gravity acting on an object, and volume is the amount of space an object occupies. Density specifically quantifies how tightly packed the matter in a substance is, providing a measure of compactness or concentration of matter. Therefore, the correct answer is A, Density.

4. What is the primary function of hair on the human body?

• A. Insulation
• B. Sensory perception
• C. Protection
• D. Vitamin D synthesis

Correct answer: C

Rationale: The primary function of hair on the human body is protection. Hair acts as a barrier to protect the skin from external factors such as sunlight, dust, and other environmental elements. While hair can also provide some insulation by trapping heat near the body and contribute to sensory perception by detecting touch or movements, its main role is to safeguard the skin from potential harm, making protection the most essential function. Vitamin D synthesis is primarily related to the skin's exposure to sunlight and is not a direct function of hair.

5. Which type of fiber is insoluble and promotes gut motility?

• A. Pectin
• B. Cellulose
• C. Beta-gluca
• D. Guar gum

Correct answer: B

Rationale: A) Pectin is a soluble fiber found in fruits and vegetables. It forms a gel-like substance in the gut and can help lower cholesterol levels. B) Cellulose is an insoluble fiber found in plants, particularly in the cell walls of fruits, vegetables, and whole grains. It adds bulk to the stool and promotes gut motility by aiding in the movement of food through the digestive system. C) Beta-glucan is a soluble fiber found in oats and barley. It can help lower cholesterol levels and improve blood sugar control. D) Guar gum is a soluble fiber derived from guar beans. It can help with digestion and may have a role in managing blood sugar levels. In this case, the question specifically asks for the type of fiber that is insoluble and promotes gut motility, which is characteristic of cellulose.

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