Nursing Elites

1. When is work done on an object?

• A. Only when the object's velocity changes
• B. Only when a force is applied to the object
• C. Whenever there is a force exerted on the object causing displacement
• D. Only when the object is lifted vertically

Correct answer: C

Rationale: Work is done on an object whenever a force causes displacement in the object's position. According to the work-energy principle, work is calculated as the force applied multiplied by the distance the object moves in the direction of the force. Therefore, work can occur whenever there is a force exerted on the object resulting in displacement, regardless of whether the object's velocity changes or it is lifted vertically. Choice A is incorrect because work can be done even without a change in velocity. Choice B is incorrect as work requires both force and displacement, not just the application of force. Choice D is incorrect because work is not limited to vertical lifting; it can happen in any direction as long as there is a force causing displacement.

2. What does potency refer to in regards to cells?

• A. The cell's ability to survive
• B. The cell's ability to move
• C. The cell's ability to divide rapidly
• D. The cell's ability to differentiate

Correct answer: D

Rationale: Potency refers to a cell's potential to differentiate into different cell types. It is not related to the cell's ability to survive (Choice A), move (Choice B), or divide rapidly (Choice C). Stem cells, for example, exhibit varying degrees of potency based on their capacity to give rise to various cell types. Therefore, the correct answer is D as it accurately defines the concept of potency in cells.

3. Which of the following blood vessels carries oxygenated blood away from the heart?

• A. Pulmonary artery
• B. Aorta
• C. Superior vena cava
• D. Inferior vena cava

Correct answer: B

Rationale: The aorta is the correct answer because it is the main artery in the body that carries oxygenated blood away from the heart to the rest of the body. The pulmonary artery carries deoxygenated blood from the heart to the lungs for oxygenation. The superior and inferior vena cava are veins that carry deoxygenated blood from the body back to the heart. Therefore, choices A, C, and D are incorrect as they do not carry oxygenated blood away from the heart.

4. What term describes the functional unit of a skeletal muscle responsible for muscle contraction?

• A. Myofibril
• B. Sarcomere
• C. Tendon
• D. Myoglobin

Correct answer: B

Rationale: The correct answer is B, 'Sarcomere.' The sarcomere is indeed the functional unit of a skeletal muscle responsible for muscle contraction. It is composed of actin and myosin filaments that interact to generate muscle contraction. Choice A, 'Myofibril,' is incorrect as myofibrils are composed of sarcomeres, not the functional units themselves. Choice C, 'Tendon,' is incorrect as tendons connect muscles to bones and do not directly participate in muscle contraction. Choice D, 'Myoglobin,' is incorrect as myoglobin is a protein that stores oxygen in muscle cells and is not directly involved in muscle contraction.

5. Melanin, the pigment responsible for skin color, is produced by

• A. Keratinocytes (These cells produce keratin)
• B. Melanocytes
• C. Sebocytes (These cells produce sebum)
• D. Langerhans cells (These cells are part of the immune system)

Correct answer: B

Rationale: Melanocytes are the cells responsible for producing melanin, the pigment that determines skin color. Melanin gives skin its color and protects it from the harmful effects of UV radiation. Keratinocytes produce keratin, a tough protein that forms the outer layer of the skin, hair, and nails. Sebocytes produce sebum, an oily substance that helps moisturize and protect the skin. Langerhans cells are a type of immune cell found in the skin that play a role in protecting against infections and foreign substances but do not produce melanin.

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