Consider the following statements regarding the impact of deforestation on the carbon cycle: 1. The amount of carbon dioxide in the air will increase. 2. The earth's temperature will likely decrease significantly. 3. Photosynthesis will increase, balancing the CO2 levels. Which of the statements given above is/are correct?

The correct option is (a). Explanation Forests act as significant carbon sinks within the biogeochemical carbon cycle. They regulate atmospheric composition by sequestering carbon through photosynthesis. Deforestation disrupts this equilibrium, impacting both the concentration of greenhouse gases and the Earth's thermal balance. Statement-wise Analysis: - Statement 1 is Correct: Trees absorb carbon dioxide (CO2) from the atmosphere during photosynthesis. When forests are cut down, this absorption ceases. Additionally, the carbon stored in the trees is released back into the atmosphere as CO2 if the wood is burned or decomposes. Consequently, the concentration of CO2 in the air increases. - Statement 2 is Incorrect: Carbon dioxide is a potent greenhouse gas responsible for trapping heat in the atmosphere. An increase in atmospheric CO2 intensifies the greenhouse effect, leading to a rise in the Earth's average temperature (Global Warming), not a decrease. - Statement 3 is Incorrect: Photosynthesis is the process performed by plants to convert light energy into chemical energy, utilizing CO2. Deforestation reduces the total vegetation cover, thereby decreasing the overall rate of photosynthesis. This reduction diminishes the ecosystem's capacity to absorb CO2, exacerbating the imbalance rather than correcting it. Key Takeaway: Deforestation disrupts the carbon cycle by simultaneously releasing stored carbon and removing the natural mechanism (photosynthesis) required to sequester atmospheric carbon dioxide, directly contributing to global warming.

NCERT Class 7 Environment & Ecology — Chapter 1: Forests: our lifeline

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Consider the following statements regarding the impact of deforestation on the carbon cycle:

The amount of carbon dioxide in the air will increase.
The earth's temperature will likely decrease significantly.
Photosynthesis will increase, balancing the CO2 levels.

Which of the statements given above is/are correct?

Official previous-year question

Verified 1 Aug 2026.

Options

A1 only
B2 only
C1 and 3 only
D1, 2 and 3

Did you get this right?

Solution

The correct option is (a).

Explanation

Forests act as significant carbon sinks within the biogeochemical carbon cycle. They regulate atmospheric composition by sequestering carbon through photosynthesis. Deforestation disrupts this equilibrium, impacting both the concentration of greenhouse gases and the Earth's thermal balance.

Statement-wise Analysis:

Statement 1 is Correct: Trees absorb carbon dioxide (CO₂) from the atmosphere during photosynthesis. When forests are cut down, this absorption ceases. Additionally, the carbon stored in the trees is released back into the atmosphere as CO₂ if the wood is burned or decomposes. Consequently, the concentration of CO₂ in the air increases.
Statement 2 is Incorrect: Carbon dioxide is a potent greenhouse gas responsible for trapping heat in the atmosphere. An increase in atmospheric CO₂ intensifies the greenhouse effect, leading to a rise in the Earth's average temperature (Global Warming), not a decrease.
Statement 3 is Incorrect: Photosynthesis is the process performed by plants to convert light energy into chemical energy, utilizing CO₂. Deforestation reduces the total vegetation cover, thereby decreasing the overall rate of photosynthesis. This reduction diminishes the ecosystem's capacity to absorb CO₂, exacerbating the imbalance rather than correcting it.

Key Takeaway: Deforestation disrupts the carbon cycle by simultaneously releasing stored carbon and removing the natural mechanism (photosynthesis) required to sequester atmospheric carbon dioxide, directly contributing to global warming.

Your note

More from Chapter 1: Forests: our lifeline

With reference to the structure of a forest, consider the following statements: 1. The branchy part of a tree above the stem is known as the crown. 2. The roof-like structure formed by the branches is called the root system. 3. The forest floor is the only layer found in a forest. Which of the statements given above is/are correct?

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Consider the following statements regarding the vegetation layers in a forest: 1. Giant and tall trees constitute the top layer. 2. Shrubs and tall grasses form the lowest layer of the forest. 3. Herbs form the lowest layer of vegetation in the forest. Which of the statements given above is/are correct?

easy

In a dense forest ecosystem, the forest floor receives minimal sunlight primarily due to:

easy

With reference to the role of forests in the water cycle, consider the following statements: 1. Trees release water vapour into the air through the process of condensation. 2. The forest canopy intercepts raindrops, preventing them from hitting the ground directly. 3. Forests facilitate the infiltration of water into the ground. Which of the statements given above is/are correct?

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Consider the following statements about the "forest floor": 1. The forest floor is generally dark due to the dense canopy above. 2. The forest floor is completely devoid of any dead or decaying matter. 3. The forest floor is sterile and supports no living organisms. Which of the statements given above is/are correct?

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The correct option is (a).

Explanation

Statement-wise Analysis:

Statement 1 is Correct: Trees absorb carbon dioxide (CO₂) from the atmosphere during photosynthesis. When forests are cut down, this absorption ceases. Additionally, the carbon stored in the trees is released back into the atmosphere as CO₂ if the wood is burned or decomposes. Consequently, the concentration of CO₂ in the air increases.
Statement 2 is Incorrect: Carbon dioxide is a potent greenhouse gas responsible for trapping heat in the atmosphere. An increase in atmospheric CO₂ intensifies the greenhouse effect, leading to a rise in the Earth's average temperature (Global Warming), not a decrease.
Statement 3 is Incorrect: Photosynthesis is the process performed by plants to convert light energy into chemical energy, utilizing CO₂. Deforestation reduces the total vegetation cover, thereby decreasing the overall rate of photosynthesis. This reduction diminishes the ecosystem's capacity to absorb CO₂, exacerbating the imbalance rather than correcting it.