Nursing Elites

1. Cytosine and thymine are known as:

• A. Purines
• B. Pyrimidines
• C. Both
• D. None of the above

Correct answer: B

Rationale: Cytosine and thymine are known as pyrimidines because they have a single carbon ring structure. Purines, on the other hand, have a double-ring structure. Choice A ('Purines') is incorrect because purines have a double-ring structure, unlike cytosine and thymine. Choice C ('Both') is incorrect as it implies they are both purines and pyrimidines, which is not true. Choice D ('None of the above') is incorrect because cytosine and thymine are indeed pyrimidines.

2. How many chromosomes do sperm and egg produce in meiosis?

• A. 23
• B. 46
• C. 25
• D. 50

Correct answer: A

Rationale: During meiosis, sperm and egg cells produce half the number of chromosomes found in somatic cells. Each contributes 23 chromosomes, which combine to form a zygote with a total of 46 chromosomes. Choice B (46) is incorrect because this is the number of chromosomes produced in mitosis, not meiosis. Choices C (25) and D (50) are also incorrect as they do not align with the chromosome count in sex cells during meiosis.

3. Select the cell parts that are present in plant cells but not animal cells (there may be more than one answer):

• A. Cell membrane
• B. Cell wall
• C. Ribosome
• D. Chloroplast

Correct answer: B

Rationale: Plant cells have a cell wall (B) which provides structural support and protection for the cell, a feature that is not present in animal cells. The cell membrane (A) is found in both plant and animal cells. Ribosomes (C) are present in both types of cells and are responsible for protein synthesis. Chloroplasts (D) are unique to plant cells and are responsible for carrying out photosynthesis. Therefore, the correct answers are B and D because the cell wall and chloroplast are specific to plant cells, while the cell membrane and ribosomes are found in both plant and animal cells.

4. Enzymes can _ reactions.

• A. Catalyze
• B. Inhibit
• C. Stop
• D. None of the above

Correct answer: A

Rationale: Enzymes function as catalysts that promote and accelerate chemical reactions in biological systems. They do this by lowering the activation energy required for the reactions to occur, thereby speeding up the process without being consumed in the reaction. Enzymes facilitate reactions rather than inhibiting or stopping them. Therefore, the correct answer is 'Catalyze.' 'Inhibit' and 'Stop' are incorrect because enzymes do not hinder or halt reactions but rather enhance them.

5. What is the function of decomposition in the carbon cycle?

• A. To produce light energy
• B. To convert carbon to fuel
• C. To release carbon dioxide
• D. To store food for consumers

Correct answer: C

Rationale: The correct answer is C: 'To release carbon dioxide.' Decomposition in the carbon cycle involves breaking down dead organic matter into simpler substances. During this process, carbon is released in the form of carbon dioxide back into the atmosphere. This release of carbon dioxide is essential for recycling carbon and making it available for use by living organisms. Choices A, B, and D are incorrect because decomposition does not produce light energy, convert carbon to fuel, or store food for consumers; its primary role is to recycle carbon through the release of carbon dioxide.

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