Question

How does photosynthesis convert sunlight into chemical energy?

Answer 1

Photosynthesis converts sunlight into chemical energy through two main stages: the light-dependent reactions and the Calvin cycle. In the light-dependent reactions, which occur in the thylakoid membranes of chloroplasts, chlorophyll absorbs sunlight, exciting electrons to higher energy levels. These electrons pass through an electron transport chain, generating ATP and NADPH, two energy-rich molecules. During this process, water molecules are split, releasing oxygen as a byproduct. The Calvin cycle, occurring in the chloroplast stroma, uses ATP and NADPH to fix carbon dioxide into an organic molecule called ribulose-1,5-bisphosphate (RuBP) in a reaction catalyzed by the enzyme RuBisCO. This fixed carbon undergoes a series of reactions to form glucose, a stable molecule storing chemical energy. Through this process, photosynthesis sustains life on Earth by producing energy for plants and oxygen for the atmosphere.

Answer 2

Photosynthesis is the process through which plants convert sunlight into chemical energy. It begins when chlorophyll in the plant cells absorbs sunlight, exciting electrons. These electrons travel through the electron transport chain, causing water molecules to split and release oxygen as a byproduct. The energy from the excited electrons is used to produce ATP and NADPH, two molecules that store energy. In the second stage, known as the Calvin cycle, the ATP and NADPH are used to fix carbon dioxide from the air into glucose. This glucose stores chemical energy that the plant can use for growth and other processes.