Which of the following substances protects the skin from ultraviolet radiation?
Melanin.
Perspiration.
Sebum.
Keratin.
The Correct Answer is A
Melanin is a pigment produced by cells called melanocytes in the skin.
It protects the skin from ultraviolet (UV) radiation by absorbing and dissipating over 99.9% of absorbed UV radiation.
This helps to prevent DNA damage and other adverse effects of UV radiation on the skin.
Choice B. Perspiration is not correct because it is a fluid produced by sweat glands in the skin that helps to regulate body temperature, but it does not protect the skin from UV radiation.
Choice C. Sebum is not correct because it is an oily substance produced by sebaceous glands in the skin that helps to lubricate and protect the skin, but it does not protect the skin from UV radiation.
Choice D. Keratin is not correct because it is a fibrous protein that provides strength and durability to the skin, hair and nails, but it does not protect the skin from UV radiation.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A myocardial infarction, commonly known as a heart attack, occurs when blood flow decreases or stops in the coronary artery of the heart, causing damage to the heart muscle.
Choice B is incorrect because the aorta is not a blood vessel of the heart.
The aorta is the main artery that carries oxygenated blood from the heart to the rest of the body.
Choice C is incorrect because the pulmonary blood vessels are not affected by a myocardial infarction.
The pulmonary blood vessels carry deoxygenated blood from the heart to the lungs.
Choice D is incorrect because the vena cava is not a blood vessel of the heart.
The vena cava is a large vein that carries deoxygenated blood from the body to the heart.
Correct Answer is C
Explanation
The data in the table shows that as the number of filters (and therefore the mass) increases, the terminal velocity also increases.
This means that the heavier objects (with more filters) are falling faster than the lighter objects (with fewer filters).
Choice A is not supported by the data in the table.
Terminal velocity is indeed when the force of gravity is equal to air resistance, but this definition does not provide any information about the relationship between mass and terminal velocity.
Choice B is also not supported by the data in the table.
The data does not provide any information about the time it takes for an object to reach terminal velocity.
Choice D is not supported by the data in the table.
The data shows that as the number of filters increases, the terminal velocity also increases.
This means that the greater the number of filters, the greater (not smaller) the terminal velocity.
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