CBSE Class 8 Science Chapter 5 Conservation of Plants And Animals Important Questions With Answers Long Answer Questions
Question 1. Is deforestation associated with global warming? Explain.
Answer: Trees (and other plants) use carbon dioxide gas from the atmosphere for the process of food making called photosynthesis. When a lot of trees are cut down during deforestation, then lesser number of trees will be left. The lesser number of trees will use up less carbon dioxide, due to which the amount of carbon dioxide in the atmosphere will still increase. In this way. Deforestation increases the level of carbon dioxide in the atmosphere. Carbon dioxide gas traps the sun’s heat rays reflected by the Earth (causing the greenhouse effect). Trapping of heat rays by carbon dioxide increases the temperature of Earth’s atmosphere. This will lead to global warming. The gradual increase in the overall temperature of Earth’s atmosphere due tothe greenhouse effect caused by the increased level of carbon dioxide in the atmosphere is called global warming.
Question 2. How does deforestation lead to frequent floods and droughts?
Answer: When the forest trees are cut down, the number of trees decreases, which results in less transpiration. Reduced transpiration causes a decrease in the amount of water vapour in the atmosphere, resulting in less rainfall.
When there is less rainfall in an area, then less water percolates into the ground. Due to this, the groundwater level also gets lowered. The shortage of surface water (in ponds, lakes, etc.) and groundwater due to persistent low rainfall in an area can lead to droughts.
Deforestation also leads to a decrease in the water-holding capacity of the soil. The movement of water from the soil surface into the ground is reduced. So, there are floods.
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Question 3. Which of these are the effects of deforestation? Circle ‘Yes’ or ‘No’ for the correct response.
Answer: Yes, No, Yes