Nursing Elites

1. What is the small repeating unit in the contractile apparatus of skeletal muscle?

• A. Myofibril
• B. Actin
• C. Sarcomere
• D. Myosin

Correct answer: C

Rationale: The correct answer is 'Sarcomere.' The sarcomere is the smallest repeating unit within myofibrils and is responsible for muscle contraction in skeletal muscle. It consists of overlapping actin and myosin filaments arranged in a highly organized structure that allows for the sliding of filaments during muscle contraction. 'Myofibril' (choice A) is incorrect because it is a larger structure composed of sarcomeres. 'Actin' (choice B) and 'Myosin' (choice D) are incorrect as they are individual proteins that are components of the sarcomere, not the smallest repeating unit itself.

2. What is the SI unit of measurement for momentum?

• A. Newton (N)
• B. Kilogram-meter per second (kg·m/s)
• C. Joule (J)
• D. Newton-second (N·s)

Correct answer: B

Rationale: The correct SI unit of measurement for momentum is kilogram-meter per second (kg·m/s). Momentum is a vector quantity that is calculated by multiplying an object's mass (in kilograms) by its velocity (in meters per second), resulting in the unit kg·m/s. This unit represents the quantity of motion an object possesses, taking into account both the mass and velocity of the object. Choice A, Newton (N), is the unit of force, not momentum. Choice C, Joule (J), is the unit of energy, not momentum. Choice D, Newton-second (N·s), is the unit of impulse, not momentum.

3. During which phase of meiosis do chiasmata structures form?

• A. Prophase I
• B. Prophase II
• C. Metaphase I
• D. Metaphase II

Correct answer: A

Rationale: Chiasmata structures, where crossing over occurs, form during Prophase I of meiosis. This phase is characterized by homologous chromosomes pairing up and crossing over, leading to the exchange of genetic material between non-sister chromatids. Chiasmata are visible points of contact where genetic material has been exchanged, and they play a critical role in genetic diversity. Prophase II is the phase where chromosomes condense again in the second meiotic division, but chiasmata formation occurs in Prophase I. Metaphase I is the phase where homologous chromosomes align at the metaphase plate, not where chiasmata form. Metaphase II is the phase where replicated chromosomes align at the metaphase plate in the second meiotic division, but chiasmata formation occurs earlier in Prophase I.

4. Which vitamin deficiency can lead to kidney stones?

• A. Vitamin A
• B. Vitamin B12
• C. Vitamin D
• D. Vitamin K

Correct answer: C

Rationale: The correct answer is Vitamin D. Vitamin D deficiency can lead to kidney stones because Vitamin D helps regulate calcium levels in the body. Low levels of Vitamin D can result in increased calcium absorption from the intestines, leading to higher levels of calcium in the urine, which can form kidney stones. Choices A, B, and D are incorrect as deficiencies in these vitamins are not directly associated with kidney stone formation.

5. If a biochemist isolates a large amount of pyruvate, which part of the cell is he working with?

• A. Chloroplasts
• B. Cytoplasm
• C. Mitochondria
• D. Nucleus

Correct answer: B

Rationale: The correct answer is B: Cytoplasm. Pyruvate is a product of glycolysis, a metabolic pathway that takes place in the cytoplasm of the cell. Therefore, a biochemist isolating a large amount of pyruvate would be working with the cytoplasm of the cell. Choice A, Chloroplasts, is incorrect because pyruvate is not produced in chloroplasts, which are responsible for photosynthesis. Choice C, Mitochondria, is incorrect as pyruvate is produced in the cytoplasm before entering the mitochondria for further metabolism. Choice D, Nucleus, is incorrect as the nucleus is not involved in the production or isolation of pyruvate, which is a metabolic intermediate.

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