Which statement best defines photosynthesis?

• A. Plants using energy in sunlight to carry out chemical reactions like producing sugar to feed the plant
• B. The breakdown of sugar into energy in the absence of sunlight
• C. The uptake of minerals from soil for growth
• D. The release of energy from sugar during respiration

Answer: (A)

Photosynthesis is the process where plants capture light energy and use it to drive chemical reactions that build sugars, which the plant uses for growth and energy. The statement describes plants using energy from sunlight to power chemical changes that produce sugar to feed the plant, which is exactly what photosynthesis does. This energy stored in the sugars is what fuels plant life and, ultimately, life on Earth since it provides the oxygen we breathe. The other ideas describe different processes: breaking down sugar to release energy without light refers to respiration; taking up minerals from soil is nutrient uptake, not energy capture; and releasing energy from sugar during respiration is again respiration. So the best definition is the one that links light energy to building sugars that feed the plant.