First 211 words of the document:
Photosynthesis occurs in two stages. These stages are called the light
reactions and the dark reactions. The light reactions take place in the
presence of light. The dark reactions do not require direct light, however dark
reactions in most plants occur during the day.
Light reactions occur mostly in the thylakoid stacks of the grana. Here,
sunlight is converted to chemical energy in the form of ATP (free energy
containing molecule) and NADPH (high energy electron carrying molecule).
Chlorophyll absorbs light energy and starts a chain of steps that result in the
production of ATP, NADPH, and oxygen (through the splitting of water).
Oxygen is released through the stomata. Both ATP and NADPH are used in
the dark reactions to produce sugar.
Dark reactions occur in the stroma. Carbon dioxide is converted to sugar
using ATP and NADPH. This process is known as carbon fixation or the Calvin
cycle. Carbon dioxide is combined with a 5-carbon sugar creating a 6-carbon
sugar. The 6-carbon sugar is eventually broken-down into two molecules,
glucose and fructose. These two molecules make sucrose or sugar.