UGC NET Questions (Paper – 1)

Statements A, B, D and E are correct and consistent with basic climate science. Statement A correctly lists major anthropogenic greenhouse gases, statement B explains how they trap outgoing long-wave radiation, statement D points to human-induced enhancement of global warming and statement E recognises the protective role of stratospheric ozone. Statement C is incorrect because the natural greenhouse effect is essential for maintaining Earth’s mean temperature at a habitable level. Therefore, the only combination that includes all true statements while excluding the false one is A, B, D and E.

Option A:
Option A is incorrect because it includes A, B and D but omits E. While A, B and D are indeed correct statements, E is also correct as stratospheric ozone shields living organisms from harmful ultraviolet radiation. By leaving out a true statement, this option does not fully capture the set of correct statements.

Option B:
Option B is correct because it includes statements A, B, D and E, all of which are scientifically accurate. It excludes statement C, which falsely portrays the greenhouse effect as entirely harmful and ignores its natural role in maintaining habitable temperatures. Hence, this option represents the complete and precise set of correct statements asked for in the question.

Option C:
Option C is incorrect because it adds statement C to the set of otherwise correct statements A, B and D. Statement C is wrong since the greenhouse effect in its natural form is beneficial and only its anthropogenic enhancement is problematic. Including a false statement makes this combination unacceptable.

Option D:
Option D is incorrect because it combines B, C, D and E. Although B, D and E are correct, the presence of statement C, which misrepresents the greenhouse effect as wholly harmful, makes the entire combination wrong. A valid answer must exclude all incorrect statements.

A carbon footprint quantifies the total greenhouse gas emissions associated with an activity or entity. It expresses different greenhouse gases in a common unit of carbon dioxide equivalent. This helps compare and manage contributions to climate change. Therefore the description in the question clearly corresponds to a carbon footprint.

Option A:
Carbon footprint is specifically used to track how much climate forcing gases are emitted. It can be calculated for individuals,organisations,products or even countries. Because the definition in the stem mentions greenhouse gases and carbon dioxide equivalent,this term fits exactly.

Option B:
An ecological niche refers to the functional role and position a species occupies in an ecosystem. It has nothing to do with measuring greenhouse gas emissions. Hence it does not match the meaning described in the question.

Option C:
Energy budget generally denotes the balance between energy input and output in a system,such as a city or organism. While related to resource use,it is not a standard measure of greenhouse gas emissions. Therefore it is not the best answer here.

Option D:
Water footprint measures the amount of freshwater used to produce goods and services consumed by an individual or community. It focuses on water use,not greenhouse gas emissions. Thus it does not correspond to the definition given in the stem.

Statements A, B and D are correct and together explain the distinction between mitigation and adaptation. Mitigation is about reducing emissions, adaptation is about adjusting systems to cope with impacts and climate-resilient crops are a clear example of adaptation. Statement C is conceptually incorrect in this context because afforestation and tree planting as carbon sinks are typically classified as mitigation actions, although they may have some adaptive co-benefits. Hence, the combination that includes A, B and D only is the correct answer.

Option A:
Option A is incorrect because it includes A and B but omits D, which is also a correct example of adaptation. While A and B provide definitions, leaving out D means the option does not fully represent the set of correct statements requested. A complete answer must recognise a concrete adaptation example as well.

Option B:
Option B is incorrect because it groups B and D only, leaving out A. Although B and D are correct, A is also correct in defining mitigation, and the question asks for all correct statements. Excluding a valid definition of mitigation makes this combination incomplete.

Option C:
Option C is correct because it brings together the accurate definition of mitigation, the accurate definition of adaptation and a valid example of adaptation in the form of climate-resilient crops. It appropriately excludes C, which mislabels a typical mitigation measure as adaptation. By balancing conceptual clarity with relevant examples, this option best fits the question.

Option D:
Option D is incorrect because it treats all four statements A, B, C and D as correct. Since C misclassifies tree planting solely as adaptation, accepting it alongside the other statements blurs the important conceptual distinction between mitigation and adaptation. The presence of this incorrect statement invalidates the combination.

Heat waves and shifting patterns of mosquitoes and other vectors are closely linked to changes in temperature and rainfall patterns. These are direct manifestations of climate change. The stem connects heat stress and vector borne diseases to a type of change,which clearly is climate change. Therefore Option C is the correct choice.

Option A:
Industrial change may alter employment and pollution but does not by itself explain systematic shifts in temperature and disease vectors. It is not the most accurate term here.

Option B:
Demographic change refers to shifts in population size, age and distribution. While these affect vulnerability,they are not the main driver named in scientific assessments for heat stress trends.

Option C:
Climate change alters temperature,precipitation and extreme weather patterns,creating conditions favourable for some vectors and harmful to health. This is exactly the link mentioned in the question.

Option D:
Technological change can influence health through new tools and risks,but it is not the primary cause of the specific trends in heat stress and vector distribution described in the stem.

Among greenhouse gases emitted by human activities, carbon dioxide contributes the most to anthropogenic global warming in terms of total radiative forcing. It is released mainly from burning fossil fuels, deforestation and industrial processes. Although other gases like methane and nitrous oxide have higher warming potential per molecule, their concentrations and total forcing are lower. Hence, carbon dioxide is regarded as the primary driver of the enhanced greenhouse effect, making option D correct.

Option A:
Option A, nitrous oxide, is a potent greenhouse gas but its atmospheric concentration and total contribution to warming are smaller compared to carbon dioxide. It is significant in agriculture and industry, yet not the largest contributor overall.

Option B:
Option B, methane, has a higher global warming potential than carbon dioxide per unit mass but is present in much lower concentrations. Its total radiative forcing is less than that of carbon dioxide, so it is not the largest contributor to anthropogenic warming.

Option C:
Option C, chlorofluorocarbons, are powerful greenhouse gases and ozone-depleting substances, but due to regulation under the Montreal Protocol, their emissions have declined. Their overall contribution is less than that of carbon dioxide.

Option D:
Option D is correct because carbon dioxide is emitted in very large quantities from energy, transport and land-use change. Its long atmospheric lifetime and cumulative build-up make it the major contributor to human-induced climate change.

The Paris Agreement specifies the long term goal of holding the increase in global average temperature to well below 2 degrees Celsius above pre industrial levels and to pursue efforts to limit the temperature increase to 1.5 degrees. The stem explicitly uses the phrase “well below” and then mentions pursuing efforts for 1.5 degrees,which confirms that the blank should be 2. Therefore Option C is the correct choice.

Option A:
A target of 1 degree is not the stated “well below” threshold in the Paris Agreement and does not appear as the main temperature limit in its text.

Option B:
1.5 degrees is included in the Paris Agreement as an aspirational effort goal (“pursuing efforts to limit to 1.5”),but it is not the number that follows “well below” in the main clause.

Option C:
The 2 degree figure is the key reference point in the Paris Agreement: parties agreed to keep warming well below 2°C and pursue efforts toward 1.5°C. This matches the stem exactly.

Option D:
4 degrees is far above agreed limits and is associated with dangerous warming scenarios,not the Paris temperature goal.

Global warming is driven largely by enhanced greenhouse gas concentrations that trap heat, altering climate patterns. Ozone depletion, on the other hand, involves breakdown of ozone molecules in the stratosphere by chlorine and bromine released from substances such as CFCs and halons. While the two issues interact in complex ways, they are scientifically distinct problems with different primary causes, effects and treaties.

Option A:
Option A is incorrect because global warming and ozone depletion are not identical; conflating them leads to conceptual confusion and wrong policy responses.

Option B:
Option B is correct as it clearly separates the temperature-related phenomenon linked to greenhouse gases from the UV-shielding issue linked to ozone chemistry and CFCs.

Option C:
Option C is incorrect; volcanic eruptions and earthquakes are not the sole or main causes of these global environmental changes.

Option D:
Option D is incorrect because ozone depletion actually increases, not reduces, UV-B reaching the surface.

Statements A, B, D and F are correct, showing that environmental factors interact with other drivers of migration, that people sometimes move as an adaptation strategy, that policies must consider livelihoods and rights and that improved data are needed. Statement C is wrong because environmental migration can be temporary, seasonal or permanent, and E is wrong because internal movements are an important part of environment–migration linkages. Thus, the option that includes A, B, D and F and excludes C and E is correct.

Option A:
Option A is incorrect because it omits D and F, ignoring the need for protective and livelihood-sensitive policies and for better evidence to guide them. While it captures environmental drivers and adaptation, it does not reflect the policy and research dimensions fully.

Option B:
Option B is correct as it brings together the most widely accepted points about environmental migration while rejecting overly rigid or dismissive views. It recognises complexity, adaptation, policy responsibilities and knowledge gaps, which matches the conceptual treatment in this unit.

Option C:
Option C is incorrect since it includes C, which wrongly states that all movement is permanent, even though migration responses to environmental change often include circular and seasonal patterns. Including C means the option mixes true and false statements.

Option D:
Option D is incorrect because it accepts E, which claims internal migration is irrelevant, and excludes A. Internal movements are central to environment–migration debates, so this combination seriously misrepresents the field.

Statement C is clearly wrong because climate change can affect food production, availability and access, which in turn influences nutrition and health. Statements A, B and D are correct as they reflect established links between heatwaves and mortality, climate-sensitive disease vectors and disruption of health systems by extreme events. Since only C is incorrect, the combination that identifies C alone as wrong is the correct answer.

Option A:
Option A is incorrect because it treats both A and C as wrong, whereas statement A is accurate. Rising temperatures and more frequent heatwaves are associated with heat stress, dehydration and increased mortality, especially among vulnerable groups. Including a correct statement in the wrong set makes the option unacceptable.

Option B:
Option B is incorrect because it marks both C and D as wrong. While C is wrong, D is correct since floods, storms and other extremes can damage hospitals, supply chains and health infrastructure. Misclassifying D as wrong contradicts disaster and health studies.

Option C:
Option C is incorrect because it claims A, C and D are all wrong. A and D are correct descriptions of climate-related health impacts. By placing them in the wrong set, this option conflicts with widely accepted scientific assessments.

Option D:
Option D is correct because it isolates statement C as the only incorrect statement. It acknowledges that climate change can and does influence food security and nutrition, which C wrongly denies, while recognising that A, B and D accurately describe other health impacts.

Over a 100-year period, nitrous oxide has a much higher global warming potential per unit mass than carbon dioxide or methane, so each kilogram emitted traps far more heat.

Option A:
Incorrect; carbon dioxide is used as the reference gas with a GWP of 1 and has lower GWP per unit mass than nitrous oxide, even though its total impact is large due to volume emitted.

Option B:
Incorrect; methane has higher GWP than CO₂ but still lower than nitrous oxide on a 100-year horizon.

Option C:
Incorrect; although water vapour is an important greenhouse gas, it is not usually assigned a standard GWP in this way and is strongly controlled by temperature.

Option D:
Correct; nitrous oxide has the highest GWP among the listed gases over a 100-year time frame.

Desertification refers to land degradation in drylands resulting from both climatic variations and human activities. It leads to reduced biological productivity,loss of vegetation and expansion of barren lands. The stem mentions fertile land becoming degraded and barren in arid and semi arid regions,which corresponds exactly to desertification. Therefore desertification is the correct answer.

Option A:
Desertification is recognised as a major global environmental issue and is addressed under the UN Convention to Combat Desertification. By undermining livelihoods,it also contributes to poverty and migration. These features reinforce why it matches the description given.

Option B:
Salinisation occurs when soluble salts accumulate in the soil,usually due to improper irrigation practices. While salinity can contribute to desert like conditions,it is only one specific form of land degradation and does not cover the broader process described.

Option C:
Waterlogging results from excessive accumulation of water in the root zone,which can suffocate plants. It is more commonly associated with high rainfall or poorly drained irrigated areas rather than general dryland degradation.

Option D:
Urbanisation is the growth of towns and cities and changes in population distribution. Although it can increase pressure on land,it is a demographic and settlement process,not the gradual transformation of drylands into barren areas described in the stem.

Global warming is conventionally defined as the rise in the average temperature of the Earth’s surface air and oceans over decades. This increase is driven primarily by human induced greenhouse gas emissions. The stem clearly points to a long term increase in average temperature,so “surface” is the correct qualifier. It aligns with how global warming is measured and discussed in climate science.

Option A:
The core refers to the innermost part of the Earth and its temperature changes do not capture climate trends experienced by living organisms. Global warming discussions rarely focus on core temperature,so Option A is inaccurate.

Option B:
Surface temperature records from land and sea provide the key empirical basis for assessing global warming. These datasets show a clear upward trend over the last century. This is precisely the aspect highlighted in the stem.

Option C:
The crust describes the solid outer shell of the Earth and its temperature is uneven and not used as the primary climate indicator. Thus Option C does not match the standard definition of global warming.

Option D:
The mantle is a deep interior layer and its thermal behaviour is largely independent of atmospheric greenhouse gas levels. It is not the focus of climate change discussions,so Option D is not appropriate.

Carbon dioxide is the primary greenhouse gas emitted by human activities,especially from burning fossil fuels for electricity,transport and industry. Its long atmospheric lifetime and high volume make it the dominant driver of anthropogenic climate change. The stem explicitly links the gas to combustion of coal,oil and natural gas,which clearly points to carbon dioxide. Hence Option A is correct.

Option A:
Carbon dioxide concentrations have been rising steadily since the industrial revolution,enhancing the greenhouse effect. Because of this central role,international climate agreements focus heavily on reducing CO₂ emissions. This explanation fits the description in the question.

Option B:
Methane is also a potent greenhouse gas and arises from agriculture,fossil fuel extraction and waste,but its global emissions from burning fossil fuels are smaller in volume than CO₂. It is therefore not the most significant gas in the specific context described.

Option C:
Ozone acts as a greenhouse gas in the troposphere but is not emitted directly in large amounts from fossil fuel combustion. It is mainly formed as a secondary pollutant,so it does not match the stem as closely as carbon dioxide.

Option D:
Carbon monoxide is a toxic gas produced by incomplete combustion and has health impacts,but its direct greenhouse effect is relatively weak compared to CO₂. Thus it is not the best answer here.

A carbon sink is any system that absorbs more carbon dioxide from the atmosphere than it emits,thereby reducing net greenhouse gas levels. Forests,oceans and certain soils act as major sinks. The stem’s description of a reservoir that stores more carbon than it releases fits this definition exactly,so sink is the correct word.

Option A:
A source is the opposite of a sink; it emits more carbon than it absorbs. Industrial activities and deforestation are typical carbon sources. Therefore source does not match the absorption focused description in the question.

Option B:
A sink helps slow the rate of climate change by temporarily removing carbon dioxide from the atmosphere. Recognising and protecting natural sinks is an important mitigation strategy. This concept aligns closely with the idea described in the stem.

Option C:
A budget refers to the balance of emissions and removals in the global carbon cycle. While related,it is not the term for the specific reservoirs that absorb carbon. Hence budget cannot properly fill the blank.

Option D:
Offset usually denotes an action that compensates for emissions elsewhere, such as funding tree planting projects. It is a policy mechanism rather than the reservoir itself,so it is not the best answer.

Carbon dioxide is the most significant anthropogenic greenhouse gas in terms of total emissions. It is released in large quantities through burning coal,oil and natural gas and through deforestation. Its long atmospheric lifetime and high volume make it the main driver of human induced climate change. Therefore carbon dioxide best fits the description in the question.

Option A:
Oxygen is a major component of the atmosphere but it is not a greenhouse gas. It does not trap outgoing infrared radiation in the way greenhouse gases do. Hence it cannot be the primary greenhouse gas mentioned in the stem.

Option B:
Nitrogen makes up the largest fraction of Earth’s atmosphere. However it is largely inert and does not act as a greenhouse gas in its diatomic form. Therefore it is not responsible for the described warming effect.

Option C:
Ozone in the troposphere acts as a greenhouse gas and pollutant,but its concentration is much lower than that of carbon dioxide. It is important locally but is not the primary anthropogenic greenhouse gas globally. Thus it is not the best answer here.

Option D:
Carbon dioxide is produced by combustion processes in power plants,industry and transport as well as by land use changes. It accumulates in the atmosphere and enhances the greenhouse effect. This makes it the central gas referred to in the question.