Nursing Elites

1. During which phase is the chromosome number reduced from diploid to haploid?

• A. S phase
• B. interphase
• C. mitosis
• D. meiosis I

Correct answer: D

Rationale: The correct answer is 'meiosis I.' During meiosis I, the chromosome number is reduced from diploid to haploid through two rounds of division. Choice A ('S phase') is incorrect as the S phase is part of the cell cycle where DNA is replicated. Choice B ('interphase') is also incorrect as interphase is the phase where the cell prepares for division. Choice C ('mitosis') is incorrect as mitosis is a process where a diploid cell divides to produce two identical diploid daughter cells, maintaining the chromosome number.

2. A cell from heart muscle would more than likely contain an unusually high proportion of which of the following?

• A. lysosomes
• B. mitochondria
• C. mRNA
• D. ribosomes

Correct answer: B

Rationale: A cell from heart muscle would more than likely contain an unusually high proportion of mitochondria because the heart muscle requires a significant amount of energy to function properly. Mitochondria are the powerhouse of the cell and are responsible for producing energy in the form of ATP through cellular respiration. Therefore, to meet the high energy demands of the heart muscle, it would need a higher concentration of mitochondria compared to other cell types. Choices A, C, and D are incorrect because while lysosomes, mRNA, and ribosomes are essential components of a cell, they do not play as direct a role in meeting the high energy demands of heart muscle as mitochondria do.

3. A child is sick. They have a body temperature that exceeds 37ºC. The body senses this and begins to sweat in order to lower the temperature. What is this an example of?

• A. Positive feedback loop
• B. Negative feedback loop
• C. Both
• D. None of the above

Correct answer: B

Rationale: This is an example of a negative feedback loop. In a negative feedback loop, the body's response (sweating) works to counteract the initial stimulus of a high body temperature by cooling the body down. The goal is to return the body to homeostasis, maintaining a stable internal environment. Positive feedback loops amplify the initial stimulus rather than counteracting it, which is not the case here. Therefore, choices A and C are incorrect. Choice D is also incorrect as the situation described fits the characteristics of a negative feedback loop.

4. Which cells in the human body lack nuclei?

• A. Nerve cells
• B. Red blood cells
• C. Liver cells
• D. Connective tissue cells

Correct answer: B

Rationale: Red blood cells, also known as erythrocytes, lack nuclei in humans. This absence of a nucleus allows more space for hemoglobin, the protein responsible for carrying oxygen, making red blood cells efficient at their function of oxygen transport in the body. Nerve cells (Choice A), liver cells (Choice C), and connective tissue cells (Choice D) all possess nuclei as they require genetic material for their functions, such as cell signaling, protein synthesis, and structural support.

5. Why do cells need to use exocytosis?

• A. To obtain energy
• B. To defend against invaders
• C. To remove waste products
• D. To undergo division

Correct answer: C

Rationale: Cells need to use exocytosis to remove waste products from the cell. Exocytosis is a process where cells release molecules or substances outside the cell by fusing vesicles with the cell membrane. This process is crucial for maintaining cellular homeostasis by efficiently eliminating waste materials. Choices A, B, and D are incorrect because exocytosis is specifically involved in the expulsion of molecules, not for obtaining energy, defending against invaders, or cell division.

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