WAEC Agriculture 2017 Paper

Concept:Crops use carbon dioxide from the air as a raw material to make food in the carbon cycle.Explanation:Green plants cannot use carbon dioxide for respiration, transpiration, or decomposition.Photosynthesis is the process in which crops absorb carbon dioxide through their leaves.Sunlight provides the energy needed to combine carbon dioxide and water.The products of this reaction are glucose and oxygen.The equation for photosynthesis is:$$6\mathrm{CO_2} + 6\mathrm{H_2O} \xrightarrow{\text{sunlight}} \mathrm{C_6H_{12}O_6} + 6\mathrm{O_2}$$The glucose made by the crop is used for energy and growth.This glucose also carries carbon into the food chain when crops are eaten.So, in the carbon cycle, the major role of carbon dioxide in crops is to support photosynthesis.Answer:A. photosynthesis