Which process uses light energy to convert carbon dioxide and water into sugars in plants?

Which process uses light energy to convert carbon dioxide and water into sugars in plants?

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

Answer: (B)

Plants use light energy to build sugars from carbon dioxide and water in a process called photosynthesis. In chloroplasts, light energy captured by chlorophyll drives two linked sets of reactions. First, the light-dependent reactions split water, releasing oxygen and producing the energy carriers ATP and NADPH. Then the Calvin cycle uses that energy to fix carbon dioxide into sugar molecules such as glucose. The overall effect is light energy stored in chemical bonds of sugars: 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2. The other processes don’t fit because respiration releases energy by breaking down sugars and consumes oxygen, not producing sugars from CO2 and water. Transpiration is the loss of water from the plant, not a sugar-building process. Fermentation can occur without oxygen but it converts sugars into other products rather than creating sugars from CO2 and water.

Plants use light energy to build sugars from carbon dioxide and water in a process called photosynthesis. In chloroplasts, light energy captured by chlorophyll drives two linked sets of reactions. First, the light-dependent reactions split water, releasing oxygen and producing the energy carriers ATP and NADPH. Then the Calvin cycle uses that energy to fix carbon dioxide into sugar molecules such as glucose. The overall effect is light energy stored in chemical bonds of sugars: 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2.

The other processes don’t fit because respiration releases energy by breaking down sugars and consumes oxygen, not producing sugars from CO2 and water. Transpiration is the loss of water from the plant, not a sugar-building process. Fermentation can occur without oxygen but it converts sugars into other products rather than creating sugars from CO2 and water.