All living organisms depend on plants for food. Carbon dioxide is necessary for plants to prepare food through the process of phothosynthesis.
If there is no carbon dioxide in the atmosphere, plants will not be able to prepare their food and hence there will be no life on the earth. [1 mark]
Apart from this, carbon dioxide plays an important role in keeping the earth warm and maintaining the average temperature of the earth by trapping the solar radiation.[1 mark]