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
The glomerulus is the main filtering unit of the kidney.
It is formed by a network of small blood vessels (capillaries) enclosed within a sac called the Bowman’s capsule.
The blood supply to the glomerulus is provided via the afferent arteriole.
The blood then flows through the capillary network, where it gets filtered, and then leaves the glomerulus via the efferent arteriole.
Choice B. Proximal tubule is not correct because it is where the ultrafiltrate collected in the Bowman’s space drains directly into.
Choice C. Distal tubule is not correct because it is not mentioned in relation to blood exiting the glomerulus.
Choice D. Afferent arteriole is not correct because it provides blood supply to the glomerulus.
Correct Answer is D
Explanation
When viruses cause an infection, they spread their DNA, affecting healthy cells’ genetic makeup and potentially causing them to turn into cancer.
For instance, HPV infections cause the virus’ DNA to combine with the host’s DNA, disrupting the normal function of cells.
Choice A is not correct because cancerous and normal cells sharing genetic sequences do not support the hypothesis that viruses can cause cancer.
Choice B is not correct because cellular DNA having sequences related to viral sequences does not support the hypothesis that viruses can cause cancer.
Choice C is not correct because viruses and cancer cells both replicating rapidly do not support the hypothesis that viruses can cause cancer.
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