Nursing Elites

1. How many different types of nucleotides are there in DNA?

• A. one
• B. two
• C. four
• D. eight

Correct answer: C

Rationale: The correct answer is 'C: four.' DNA is composed of four different types of nucleotides: adenine, thymine, guanine, and cytosine. These nucleotides pair up in specific combinations to form the genetic code. Choices 'A: one,' 'B: two,' and 'D: eight' are incorrect because DNA consists of a set of four distinct nucleotides, not one, two, or eight.

2. 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.

3. Which animal has an open transport system?

• A. Grasshopper
• B. Earthworm
• C. Dolphin
• D. Chicken

Correct answer: B

Rationale: The correct answer is B: Earthworm. Earthworms have an open circulatory system, meaning their blood and interstitial fluid are not enclosed in blood vessels. Instead, the blood flows freely within the body cavity, allowing for direct exchange of nutrients and waste products with surrounding tissues. This lack of a closed transport system is a characteristic feature of earthworms. Choices A, C, and D are incorrect because grasshoppers, dolphins, and chickens have closed circulatory systems where the blood is enclosed within blood vessels, unlike earthworms.

4. Which organelle is the site of photosynthesis in plant cells?

• A. Mitochondria
• B. Chloroplasts
• C. Ribosomes
• D. Endoplasmic Reticulum

Correct answer: B

Rationale: The correct answer is B: Chloroplasts. Chloroplasts are responsible for conducting photosynthesis in plant cells. They contain chlorophyll, a pigment that captures light energy and converts it into chemical energy through the process of photosynthesis. Mitochondria (choice A) are known as the powerhouse of the cell and are involved in cellular respiration, not photosynthesis. Ribosomes (choice C) are responsible for protein synthesis. The endoplasmic reticulum (choice D) is involved in protein and lipid synthesis and transport within the cell, not photosynthesis.

5. Why do gardeners sometimes use salt to get rid of slugs?

• A. The salt moves from the exterior into the slug’s body.
• B. The salt causes water in the slug to move outward.
• C. The salt and slug slime merge to form a new compound.
• D. The salt’s corrosiveness breaks down the slug’s cell walls.

Correct answer: D

Rationale: Gardeners use salt to get rid of slugs because salt is corrosive and breaks down the slug's cell walls. When the slug comes into contact with salt, the salt draws moisture out of the slug's body, causing dehydration and ultimately leading to the slug's death. Choices A, B, and C are incorrect because the primary mechanism of salt in eliminating slugs is its corrosive action on the slug's body, not the movement of salt into the slug's body, outward movement of water in the slug, or merging with slug slime to form a new compound.

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