What is the fundamental process by which plants manufacture carbohydrates from raw materials using energy from light?

• A. Photosynthesis
• B. Respiration
• C. Transpiration
• D. Germination

Answer: (A)

Photosynthesis is the process by which plants use light energy to convert carbon dioxide and water into glucose, a carbohydrate, with oxygen released as a byproduct. In the chloroplasts of leaf cells, light energy drives reactions that fix CO2 and split water, building sugars that the plant can use for immediate energy or store as starch. The energy from light ends up stored in the chemical bonds of the glucose molecule, enabling growth and metabolism. This is why plants can manufacture their own carbohydrates from simple raw materials.

Other processes involve different roles for plants: respiration releases energy from sugars, transpiration is the loss of water from the plant, and germination is the sprouting of a seed using stored energy.