UGC NET Questions (Paper – 1)

Statements D and F are wrong because ozone depletion does affect terrestrial plants, phytoplankton and food webs, and the ozone layer has not yet fully recovered, requiring ongoing compliance with treaties. A, B, C and E are correct: the ozone layer filters UV-B, excess exposure increases health risks, the Montreal Protocol guides phase-out of harmful substances and protective behaviours reduce risk. Therefore, the correct answer is the combination that identifies D and F as the wrong statements.

Option A:
Option A is correct since it pinpoints both D and F as misrepresenting scientific and policy realities, while accepting A, B, C and E, which align with current understanding of ozone protection and UV impacts. It reflects both ecological and human health dimensions.

Option B:
Option B is incorrect because it singles out only D and ignores F, even though claiming treaties are no longer needed is clearly inconsistent with ongoing monitoring and gradual recovery timelines.

Option C:
Option C is incorrect as it marks only F as wrong and overlooks D, which denies the ecological consequences of ozone depletion. By failing to include D, it neglects an important environmental dimension of the issue.

Option D:
Option D is incorrect because it adds C to the list of wrong statements, even though C correctly notes that the Montreal Protocol has been central in guiding the replacement of ozone-depleting substances. Including C among wrong statements contradicts widely accepted historical facts.

Stratospheric ozone absorbs much of the Sun’s harmful UV-B radiation; when the ozone layer thins, more UV-B reaches the surface, increasing risks of skin cancers, cataracts and immune system suppression.

Option A:
Correct; it directly links ozone depletion to greater UV-B exposure and the associated health effects such as skin cancer and cataracts.

Option B:
Incorrect; indoor air pollution is mainly caused by fuels and ventilation conditions, not by changes in the ozone layer.

Option C:
Incorrect; tectonic activity and earthquakes are unrelated to atmospheric ozone levels.

Option D:
Incorrect; ozone depletion does not cause greenhouse gases to disappear; ozone issues and climate change are distinct though related problems.

The ozone layer filters out most of the Sun’s biologically harmful ultraviolet radiation,particularly UV B. Without this layer,organisms would face much higher risks of skin cancer,eye cataracts and damage to DNA. The stem refers directly to harmful solar radiation that is absorbed,which identifies ultraviolet as the correct type. Therefore Option B is right.

Option A:
Infrared radiation is associated primarily with heat and plays a role in the greenhouse effect rather than in causing severe biological damage at normal levels. The ozone layer does not primarily target infrared,so this option does not fit the question.

Option B:
Ultraviolet radiation at high intensities can damage living tissues and ecosystems. Ozone molecules in the stratosphere absorb much of this radiation,acting as a protective shield. This matches exactly the function described in the stem.

Option C:
Microwave radiation is used in communication and cooking applications and is not the main focus of ozone absorption. It interacts differently with the atmosphere,so it is not a suitable answer here.

Option D:
Radio waves have long wavelengths and low energy and are widely used for broadcasting. They are not significantly harmful at typical environmental levels and are not what the ozone layer shields us from.

The ozone layer is particularly effective at absorbing biologically harmful UV-B radiation from the sun. Without this filtering,much higher levels of UV-B would reach Earth’s surface. This would greatly increase the incidence of skin cancer,eye damage and harm to other organisms. Hence absorption of ultraviolet-B radiation is the key protective function described in the question.

Option A:
Ultraviolet-B radiation has enough energy to damage DNA and biological tissues. The ozone layer absorbs most of this band,thereby shielding living organisms. Because the question refers specifically to the protective role of the ozone layer,UV-B is the correct type of radiation.

Option B:
Infrared radiation is associated mainly with heat and plays a role in the greenhouse effect. The ozone layer is not primarily known for absorbing infrared radiation. Therefore this option does not match the protective function highlighted in the stem.

Option C:
Visible light is the portion of the spectrum that enables human vision. Most visible light passes through the atmosphere with little absorption by ozone. Since the ozone layer’s key biological protection is not related to visible light,this option is inappropriate.

Option D:
Radio waves are long wavelength electromagnetic waves used in communication. They are not strongly absorbed by the ozone layer and are not especially harmful to living tissues at natural levels. Thus they are unrelated to the protective role mentioned in the question.

Statements A, B and D are correct because they describe the protective role of stratospheric ozone, the harmful impact of CFCs and the purpose of the Montreal Protocol. The ozone layer does absorb UV-B radiation, and CFCs are a major anthropogenic cause of its depletion, which led to international regulatory efforts. Statement C is incorrect because the most prominent and persistent ozone hole has historically been observed over Antarctica, not the Arctic. Thus, the correct combination of statements is A, B and D only.

Option A:
Option A is incorrect because although A and B are true, it omits D, which is also a correct statement regarding the Montreal Protocol’s role in controlling ozone-depleting substances. Leaving out a correct statement means this option does not fully represent the set of correct statements.

Option B:
Option B is incorrect because it includes all four statements A, B, C and D, thereby treating C as correct. Since the largest well-known ozone hole is over Antarctica rather than the Arctic, statement C is factually wrong. Including a false statement invalidates the entire combination.

Option C:
Option C is correct because it collects only those statements that are consistent with established atmospheric science and international environmental policy. It recognises the protective function of ozone, the role of CFCs in depletion and the regulatory role of the Montreal Protocol while excluding the incorrect statement about the location of the largest ozone hole.

Option D:
Option D is incorrect because it assumes B, C and D are correct and omits A. Apart from incorrectly accepting C, this option also fails to include A, which accurately describes the UV-absorbing function of the ozone layer. The presence of a wrong statement and the exclusion of a correct one make this combination unacceptable.