Nursing Elites

1. In a phospholipid molecule, the head:

• A. Is hydrophilic
• B. Is hydrophobic
• C. Is on the inner side of the layer
• D. Both A and C

Correct answer: D

Rationale: The head of a phospholipid is hydrophilic (water-loving) and is located on the outer side of the lipid bilayer, interacting with water molecules. This arrangement positions the hydrophobic tails inward, away from water. Therefore, the correct answer is D. Choice A is incorrect because the head is hydrophilic, not hydrophobic. Choice B is incorrect as the head is on the outer side, not the inner side of the layer.

2. Which, if any, of the following statements are true?

• A. Water boils at approximately 100°C (212°F) at standard atmospheric pressure
• B. The boiling point is the temperature at which the vapor pressure is higher than the atmospheric pressure around the water
• C. Water boils at a lower temperature in areas of lower pressure
• D. A and C are true

Correct answer: D

Rationale: Both statements A and C are true. Water indeed boils at approximately 100°C (212°F) at standard atmospheric pressure. However, water boils at a lower temperature in areas of lower pressure due to the decreased atmospheric pressure, which affects the vapor pressure and boiling point of water. Statement B is incorrect because the boiling point is the temperature at which the vapor pressure equals the external pressure (atmospheric pressure in this case), not when it is higher.

3. Which is not part of a nucleic acid?

• A. Sulfate
• B. Phosphate
• C. Carbon
• D. Nitrogen

Correct answer: A

Rationale: Sulfate is not part of a nucleic acid. Nucleic acids, such as DNA and RNA, are composed of nucleotide units, which consist of a phosphate group, a sugar molecule (ribose in RNA and deoxyribose in DNA), and a nitrogenous base. Carbon and nitrogen are essential elements found in nucleic acids, while sulfate is not a component of nucleic acid structure. Therefore, the correct answer is A: Sulfate.

4. How does an enzyme work on a chemical reaction that occurs in a substrate?

• A. An enzyme slows down the chemical reaction.
• B. An enzyme speeds up the chemical reaction.
• C. An enzyme has no effect on the chemical reaction.
• D. An enzyme stops most chemical reactions.

Correct answer: B

Rationale: Enzymes are biological catalysts that facilitate chemical reactions by lowering the activation energy required for the reaction to occur. This allows the reaction to proceed more quickly and efficiently. Enzymes do not change the overall outcome of the reaction, but they significantly increase the rate at which it takes place. Therefore, choice B, 'An enzyme speeds up the chemical reaction,' is the correct answer. Choices A, C, and D are incorrect because enzymes do not slow down, have no effect, or stop chemical reactions; instead, they accelerate the process by lowering the activation energy.

5. During which phase of mitosis do the chromosomes align in the center of the cell?

• A. Prophase
• B. Metaphase
• C. Telophase
• D. Anaphase

Correct answer: B

Rationale: The correct answer is Metaphase. During Metaphase, the chromosomes line up along the center of the cell's equator, forming the metaphase plate. This alignment ensures that during the subsequent phase, Anaphase, the sister chromatids can separate and move towards opposite poles. Prophase is the initial phase of mitosis where chromosomes condense and the nuclear envelope breaks down. Telophase is the final phase of mitosis where two new nuclei form.

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