Nursing Elites

1. Why do high-salt content foods not require refrigeration to prevent spoilage?

• A. Osmosis
• B. Diffusion
• C. Active transport
• D. Passive transport

Correct answer: A

Rationale: Osmosis is the natural process that prevents high-salt content foods from spoiling without the need for refrigeration. Osmosis involves the movement of water across a semi-permeable membrane from an area of lower solute concentration (water) to an area of higher solute concentration (salt). In high-salt content foods, the salt acts as a preservative by drawing moisture out of bacteria or other microorganisms, making it difficult for them to survive and spoil the food. This process helps in preserving the food and preventing spoilage even without refrigeration. Choices B, C, and D are incorrect because they do not involve the specific mechanism of water movement in response to the salt concentration in high-salt content foods.

2. Which organelle is the site of energy production?

• A. Mitochondrion
• B. Vacuole
• C. Cell membrane
• D. Ribosome

Correct answer: A

Rationale: The correct answer is A: Mitochondrion. The mitochondrion is the site of energy production in a cell. It is often referred to as the powerhouse of the cell because it is where cellular respiration occurs, generating energy in the form of adenosine triphosphate (ATP) through processes like the citric acid cycle and oxidative phosphorylation. The other organelles listed play different roles in the cell - vacuoles store materials, the cell membrane regulates the movement of substances in and out of the cell, and ribosomes are involved in protein synthesis.

3. A cell containing 12 chromosomes divides into daughter cells in mitosis. How many chromosomes are in each daughter cell?

• A. 3
• B. 6
• C. 12
• D. 24

Correct answer: C

Rationale: During mitosis, the cell undergoes nuclear division without changing the number of chromosomes. Therefore, the daughter cells produced will have the same number of chromosomes as the parent cell. In this case, since the parent cell contains 12 chromosomes, each daughter cell will also have 12 chromosomes. Choices A, B, and D are incorrect because during mitosis, the chromosome number remains the same, and daughter cells inherit the same number of chromosomes as the parent cell.

4. Which of the following is true of the Krebs cycle?

• A. It is a redox reaction involving proteins produced during glycolysis
• B. It is a redox reaction involving sugars produced during glycolysis
• C. Protons are passed along a gradient to produce ATP
• D. It is also known as the glycolic acid cycle

Correct answer: B

Rationale: The Krebs cycle, also known as the citric acid cycle, involves a series of redox reactions that occur in the mitochondria. The cycle begins with the oxidation of acetyl CoA, which is derived from the breakdown of sugars produced during glycolysis. These sugars are broken down further in the Krebs cycle to produce ATP and reduce electron carriers such as NADH and FADH2. The cycle does not involve proteins produced during glycolysis. Protons are not passed along a gradient to produce ATP directly in the Krebs cycle; rather, they are used in the electron transport chain to generate ATP. The Krebs cycle is not known as the glycolic acid cycle; glycolysis is the metabolic pathway that produces pyruvate from glucose.

5. Why can animal cells use a contractile ring but plant cells cannot?

• A. Plant cells can use both methods to divide
• B. Animal cells divide faster, requiring them to pinch apart
• C. Plant cells are too rigid to use a contractile ring
• D. N/A

Correct answer: C

Rationale: Plant cells have a rigid cell wall surrounding them, which prevents them from using a contractile ring for cell division. The rigid cell wall requires plant cells to form a cell plate during cell division instead of pinching apart like animal cells with a contractile ring. Choice A is incorrect because plant cells cannot use a contractile ring due to their rigid cell wall. Choice B is incorrect as the speed of cell division is not the primary reason for the difference in cell division mechanisms between plant and animal cells. Choice D is not applicable as plant cells indeed have a specific limitation in using a contractile ring for cell division.

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