Environmental Issues MCQ: Definition and Explanation

Ans. 1. Troposphere 

Explanation: Global Warming is the process of heating up the Earth's atmosphere. It has existed since the beginning of industrialisation, but with the increase in emission of Greenhouse gases, the rate of global warming has also increased. Human activities like burning of fossil fuels and discharge of industrial gases has led to the accumulation of greenhouse gases in the Earth's atmosphere. 

These greenhouse gases trap the heat of the sun, and do not let the earth cool down to the lowest possible temperature at night. While it is very important for the survival of life, more greenhouse gases has resulted in an increase in the Earth's average temperature, which, in other words, is another name of Global Warming. In this process, most of the heat is trapped in the Troposphere of Atmosphere. So, the heat in the Troposphere increases during global warming. 

Ans. 4. Nitrogen 

Explanation: Greenhouse gases help to keep the earth warm at night by trapping the sun's heat. While it is very important for our survival, it has some ill effects as well. Too much presence of greenhouse gases increases the average temperature of the Earth, resulting in Global warming. 

The major greenhouse gases found in the Earth's atmosphere include Carbon Dioxide, Methane, Ozone, Water Vapour, and Nitrous Oxide. However, Nitrogen is not a greenhouse gas and does not have any role in Global warming. 

Ans. 1. Stratosphere 

Explanation: The atmosphere of the Earth is divided into six layers, which are Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere, Ionosphere. The Troposphere is the first one which is closest to the ground, while the Ionosphere is the last one in space. 

Ozone Layer is a belt of Ozone gas found in the Stratosphere of the Atmosphere. In this belt, the Ozone molecules utilise the UV radiation to break down into molecular oxygen and nascent oxygen, and then again recombine to form Ozone. This process finishes most of the UV radiation entering our atmosphere, and hence protects the living organisms from its ill effects. That is why, Stratosphere is also known as the Ozonosphere.

Ans. 4. Ozone Layer Depletion 

Explanation: Chlorofluorocarbons act as a catalyst in breaking down the Ozone molecule into molecular oxygen and nascent oxygen. This same reaction takes place in the Stratosphere of our atmosphere, where the Ozone layer is present. Under normal conditions, this reaction takes place at a specific pace, and is equally backed by the corresponding Ozone reformation reaction. In simple words, the number of Ozone molecules broken down and the number of Ozone molecules formed are equal under normal conditions. 

But, due to the presence of CFCs, the breakdown reaction is catalysed and its rate increases. As a result, more Ozone molecules are broken down, and less are formed. This results in the Depletion of the Ozone Layer. 

Ans. 3. South Pole 

Explanation: In the year 1980, a group of scientists working on the Atmosphere of Antarctica reported the Ozone Hole. This Ozone hole is believed to be the area where Ozone Layer has suffered maximum depletion. The Ozone hole is located over the South Pole. 

Ans. 2. Smoke and fog

Explanation: Smog is basically a mixture of smoke that contains different types of minute particles like carbon and ash, with water droplets of fog. 

There are two different types of smog:

1. Classical Smog: It is popularly known as the London smog because it is quite common in a place with cool and humid climate. Classical Smog is reducing in nature. 
2. Photochemical Smog: It is commonly known as the Los Angeles smog, as it is often seen in places with sunny and dry climate. It's particles are oxidising in nature. 

Ans. 2. Physical Environment 

Explanation: The nonliving components like landforms, climate, water-bodies, temperature, humidity, and air make up the physical space in which an organism lives. So, they are a part of the physical environment. 

On the other hand, all the living organisms are a part of the Biological Environment. 

Ans. 4. Biogeochemical Cycles 

Explanation: The minerals and compounds found on the Earth are cycled at various scales to ensure that their supply never stops. It helps the living organisms, especially the plants, in getting an uninterrupted supply of these minerals. All these cycles come under Biogeochemical Cycles. These cycles are of different types, for different minerals. Some examples are Phosphorus Cycle, Sulphur Cycle, Nitrogen Cycle, etc. 

Ans. 1. A community of organisms where there are several interrelated food chains.

Explanation: A food web describes the relation between all the food chains that exist in a particular ecosystem. It tells us how the different food chains are interlinked to each other, and what type of impact will be produced on a food chain, when another one gets disturbed. 

Ans. 4. All of the above 

Explanation: Environment is based on the relationship between its biotic and abiotic components. Both the components are extremely crucial for sustaining the environment. They interact with each other on the basis of the four interactive and functional relationships. These relationships ensure that a healthy ecological balance is always maintained.