Question

Explain the importance of carbon dioxide for (a) photosynthesis (b) warming the earth’s environment. State what would happen if excess carbon dioxide as a pollutant is released into the atmosphere.

Answer 1

(a) During photosynthesis which occurs during daytime, carbon dioxide and water in the presence of sunlight and chlorophyll is changed into carbohydrates and oxygen is released out.
Hence oxygen in the air is renewed by photosynthesis and therefore the amount of oxygen in air does not get depleted or removed from air.

(b) Infrared (I.R.), visible rays and ultra violet (U.V.) rays are present in the earth’s surface.
The reflected U.V. rays from the earth’s surface pass through the carbon dioxide in the atmosphere, but the I. R. rays are prevented by the carbon dioxide from being radiated out of the earth’s surface. This results in the earth’s environment staying warm. The thick CO₂ layer prevents the heat radiations from being radiated out which results into rise in global temperature.

Answer 2

(a)

During photosynthesis which occurs during daytime, carbon dioxide and water in the presence of sunlight and chlorophyll is changed into carbohydrates, and oxygen is released out.

\[\ce{\underset{\text{(in air)}}{Carbon dioxide} + Water ->[sunlight][chlorophyll] \underset{\text{(glucose)}}{Carbohydrates} + Oxygen}\]

Hence oxygen in the air is renewed by photosynthesis and therefore the amount of oxygen in the air does not get depleted or removed from the air.

(b)

Infrared (I.R.), visible rays and ultraviolet (U.V.) rays are present in the earth’s surface. The reflected U.V. rays from the earth’s surface pass through the carbon dioxide in the atmosphere, but the I. R. rays are prevented by the carbon dioxide from being radiated out of the earth’s surface. This results in the earth’s environment staying warm. The thick CO₂ layer prevents the heat radiations from being radiated out which results in a rise in global temperature.

Reason: It results in a rise in global temperature.