Question

Excessive exposure of humans to UV-rays results in
(i)Damage to immune system
(ii)Damage to lungs
(iii)Skin cancer
(iv)Peptic ulcers

(a)(i) and (ii)
(b) (ii) and (iv)
(c) (i) and (iii)
(d) (iii) and (iv)

Answer 1

Hint: The ozone layer is present in the stratosphere and functions as a shield against harmful UV- radiation. In the absence of this layer, the extremely harmful UV radiations will reach earth and cause great harm to organisms.

Complete answer:
The World health organization said human exposure to solar UV radiation may result in acute and chronic health effects on the skin, eye, and immune system by lowering the body's resistance to diseases. Acute effects are due to excessive UV radiation exposure and are not long term effects like a sunburn (erythema). Over the longer term, excessive UV radiation exposure can lead to degenerative changes in cells of the skin, blood vessels, and fibrous tissue leading to premature skin aging, photodermatoses, and actinic keratoses. Another chronic effect is an inflammatory reaction of the eye; too much exposure may even lead to skin cancer and cataracts.
A growing body suggests that the environmental levels of UV radiation may degrade cell-mediated immunity and enhance the risk of infectious diseases and limit the efficacy of medicines like vaccinations. It may also lead to large scale mutations to organisms, harm plants by reducing photosynthesis, and act against the health of poor and vulnerable groups especially children of the developing world. Many advancing countries are located near the equator and are exposed to the very high levels of UV radiation that occur in these regions.
So, the correct answer is ‘(i) and (iii)’.

Note: Ozone protects the immune system of living beings against various diseases by filtering out harmful UV radiation. But there are factors that lead to the depletion of the ozone layer like chlorofluorocarbons (CFCs) and halons. These gases formerly found in aerosol spray cans and refrigerants are released into the atmosphere which causes chemical reactions that break down ozone molecules, reducing ozone's ultraviolet radiation-absorbing capacity.