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. How do green plants use nitrates in the nitrogen cycle?

• A. To synthesize proteins
• B. To store food
• C. To decompose ammonia
• D. To break down nitrites

Correct answer: A

Rationale: Green plants use nitrates in the nitrogen cycle to synthesize proteins. Nitrogen is an essential component of amino acids, which are the building blocks of proteins. Plants take up nitrates from the soil through their roots and incorporate nitrogen into their proteins through the process of protein biosynthesis. This helps in their growth, development, and overall health. Choice B, 'To store food,' is incorrect because nitrates are primarily used for protein synthesis, not food storage. Choice C, 'To decompose ammonia,' is incorrect as plants do not decompose ammonia but rather utilize it through nitrification. Choice D, 'To break down nitrites,' is incorrect as plants typically convert nitrites into nitrates through a process called nitrate assimilation for protein synthesis.

3. Which one of the following best describes the function of a cell membrane?

• A. It controls the substances entering and leaving the cell.
• B. It maintains the cell's shape.
• C. It controls the substances entering the cell.
• D. It supports the cell's structures.

Correct answer: A

Rationale: The correct answer is A. The function of a cell membrane is to control the substances entering and leaving the cell. The cell membrane is selectively permeable, allowing it to regulate the movement of ions and molecules in and out of the cell to maintain internal balance and proper function. Choice B is incorrect because while the cell membrane does provide some structural support, its primary function is not to maintain the cell's shape. Choice C is incorrect because the cell membrane controls both the substances entering and leaving the cell, not just those entering. Choice D is incorrect as the primary function of the cell membrane is not to support the cell's structures but to regulate the movement of substances.

4. How should a researcher test the hypothesis that radiation from cell phones is significant enough to raise the temperature of water in a test tube?

• A. Dial a cell phone that rests beside a test tube of water, let it ring for two minutes, and record the temperature of the water before and after the two-minute interval.
• B. Dial a cell phone that rests beside a test tube of water; let it ring for two, three, and four minutes; and record the temperature of the water before and after each interval.
• C. Use three different brands of cell phone; dial each as it rests beside its own test tube of water, let it ring for two minutes, and record the temperature of the water before and after the two-minute interval.
• D. Use three different brands of cell phone, dial each and let one ring for two minutes, one for three minutes, and one for four minutes; record the temperature of the water before and after each interval.

Correct answer: A

Rationale: To test the hypothesis that radiation from cell phones raises the temperature of water in a test tube, the most appropriate method is to dial a cell phone next to a test tube of water, let it ring for a consistent two-minute interval, and record the temperature before and after. Choice A is correct because it provides a controlled approach to isolate the impact of the phone's radiation on the water temperature. Choices B, C, and D introduce additional variables that could confound the results. Choice B varies the duration of exposure, making it difficult to attribute temperature changes specifically to the radiation. Choice C introduces the factor of different cell phone brands, which could introduce variability not related to radiation. Choice D also varies exposure times and introduces the factor of multiple phone brands, making it harder to determine the direct impact of cell phone radiation on water temperature. Therefore, choice A is the most suitable option for this experiment.

5. Why does cytokinesis happen?

• A. DNA can duplicate
• B. Organelles can convert energy
• C. Bacteria can be killed
• D. Daughter cells can divide

Correct answer: D

Rationale: Cytokinesis happens at the end of mitosis to physically separate the newly formed daughter cells. This allows the cell to divide into two separate daughter cells, each containing a complete set of genetic material (DNA) and organelles. The purpose of cytokinesis is to ensure that each daughter cell receives the necessary components to function independently. Choices A, B, and C are incorrect because cytokinesis does not directly involve DNA duplication, organelles converting energy, or killing bacteria.

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