Meteorological Hazards & Disasters – Geography – UGC NET – Solved PYQs

1. Match List-I with List-II and select the correct answer from the codes given below (NOV 2017)

Codes (A B C D)

(1) A-I, B-II, C-III, D-IV
(2) A-II, B-I, C-III, D-IV
(3) A-IV, B-III, C-II, D-I
(4) A-IV, B-III, C-I, D-II

Correct Answer: (4) A-IV, B-III, C-I, D-II

The correct matching is A-IV, B-III, C-I, D-II, which means Global Climate Change Impacts in the United States – 2009, Stockholm Conference – 1972, Fourth Assessment Report of the IPCC – 2007, and Rio Conference – 1992.

The report Global Climate Change Impacts in the United States was published in 2009. It was a major scientific assessment prepared under the U.S. Global Change Research Program (USGCRP). The report examined the observed and projected impacts of climate change on various sectors of the United States, including agriculture, water resources, ecosystems, public health, energy, and coastal regions. It emphasized that climate change effects were already evident across different parts of the country and were expected to intensify in the future.

The Stockholm Conference, officially known as the United Nations Conference on the Human Environment, was held in 1972 in Stockholm, Sweden. It was the first major international conference devoted exclusively to environmental issues. The conference marked the beginning of modern global environmental governance and led to the establishment of the United Nations Environment Programme (UNEP). It highlighted the need to balance economic development with environmental protection and encouraged international cooperation on environmental challenges.

The Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) was published in 2007. This landmark report provided comprehensive scientific evidence regarding global warming and its causes. It concluded with a very high degree of confidence that most of the observed increase in global average temperatures since the mid-twentieth century was due to human activities, particularly the emission of greenhouse gases. The report played a crucial role in shaping international climate policy and public awareness regarding climate change.

The Rio Conference, formally called the United Nations Conference on Environment and Development (UNCED) or the Earth Summit, was held in 1992 in Rio de Janeiro, Brazil. The conference produced several important outcomes, including Agenda 21, the Rio Declaration on Environment and Development, the Convention on Biological Diversity (CBD), and the United Nations Framework Convention on Climate Change (UNFCCC). It established the principle of sustainable development as a central goal of global environmental policy.

The chronological sequence of these major environmental milestones reflects the evolution of international concern regarding environmental protection and climate change, beginning with the Stockholm Conference in 1972, followed by the Rio Earth Summit in 1992, the IPCC Fourth Assessment Report in 2007, and the Global Climate Change Impacts report in 2009. The correct matching is A-IV, B-III, C-I, D-II, corresponding to Option (4).

2. Match List-I with List-II and select the correct answer from the codes given below (JULY 2018)

Codes (A B C D)

(1) A-I, B-IV, C-II, D-III
(2) A-IV, B-III, C-I, D-II
(3) A-III, B-IV, C-I, D-II
(4) A-III, B-IV, C-II, D-I

Correct Answer: (3) A-III, B-IV, C-I, D-II

The correct matching is A-III, B-IV, C-I, D-II, which means Decomposition – CH₄, Transpiration – Water vapour, Respiration – CO₂, and Photosynthesis – O₂.

Decomposition is the process by which dead organic matter is broken down by microorganisms such as bacteria and fungi. In environments where oxygen is limited, particularly in wetlands, marshes, landfills, and waterlogged soils, decomposition often produces methane (CH₄). Methane is a powerful greenhouse gas and plays an important role in the global carbon cycle. This makes Decomposition → CH₄ (III) the correct match.

Transpiration is the process through which plants release water vapour into the atmosphere from tiny pores called stomata located on the surfaces of leaves. It is a vital component of the hydrological cycle and helps regulate plant temperature, nutrient transport, and atmospheric moisture content. Thus, Transpiration → Water vapour (IV) is the correct match.

Respiration is a biological process carried out by plants, animals, and microorganisms in which organic compounds are broken down to release energy. During respiration, oxygen is consumed and carbon dioxide (CO₂) is released as a by-product. This process is one of the major natural sources of atmospheric carbon dioxide and is essential for maintaining the balance of gases in the atmosphere. Hence, Respiration → CO₂ (I) is the correct match.

Photosynthesis is the process by which green plants, algae, and certain bacteria convert solar energy into chemical energy. Using carbon dioxide, water, and sunlight, plants synthesize carbohydrates and release oxygen (O₂) into the atmosphere. Photosynthesis is the primary source of atmospheric oxygen and forms the foundation of most terrestrial and aquatic food chains. Therefore, Photosynthesis → O₂ (II) is the correct match.

These four processes are fundamental components of the carbon cycle, oxygen cycle, and water cycle. Together they regulate the movement of matter and energy through ecosystems and influence atmospheric composition, climate, and biological productivity. The correct sequence is A-III, B-IV, C-I, D-II, which corresponds to Option (3).

3. Which one of the following is the main source for a vast reservoir of relatively inert nitrogen in the homosphere? (JULY 2018)

(1) Volcanic activities
(2) Fossil fuel burning
(3) Acid rain
(4) Global warming

Correct Answer: (1) Volcanic activities

The homosphere is the lower part of the atmosphere extending from the Earth’s surface to an altitude of about 80–90 kilometres. Within this region, atmospheric gases are well mixed due to continuous turbulence and vertical circulation. The atmosphere in the homosphere is composed predominantly of nitrogen (N₂), which accounts for approximately 78 percent of the total atmospheric volume, making it the most abundant gas in the Earth’s atmosphere.

Atmospheric nitrogen exists mainly in the form of molecular nitrogen (N₂), which is highly stable and relatively inert because of the strong triple bond between the two nitrogen atoms. Although nitrogen is essential for life, most organisms cannot directly utilize atmospheric nitrogen and depend on processes such as nitrogen fixation to convert it into biologically available forms.

The origin of the vast atmospheric reservoir of nitrogen is closely linked to the geological evolution of the Earth. During the early stages of Earth’s history, intense volcanic activities released enormous quantities of gases from the Earth’s interior through a process known as outgassing. These gases included water vapour, carbon dioxide, nitrogen, sulfur compounds, and other volatile substances. Over geological time, water vapour condensed to form oceans, much of the carbon dioxide became incorporated into rocks and marine sediments, while nitrogen accumulated in the atmosphere because of its chemical stability and low reactivity.

Fossil fuel burning releases nitrogen oxides and other gases into the atmosphere, but it is not the source of the Earth’s large nitrogen reservoir. Acid rain is a consequence of atmospheric reactions involving sulfur dioxide and nitrogen oxides and does not contribute to the formation of atmospheric nitrogen. Global warming is a climatic phenomenon resulting primarily from increased greenhouse gas concentrations and has no role in generating the atmospheric nitrogen reservoir.

The dominance of nitrogen in the atmosphere is a result of billions of years of geological and atmospheric evolution. Continuous volcanic degassing supplied nitrogen to the atmosphere, and because nitrogen is relatively inert, it accumulated and remained as the principal atmospheric constituent. This long-term process established the vast reservoir of atmospheric nitrogen found in the homosphere, making volcanic activities the correct answer.