Question

provide background information about energy production in plants

Answer 1

In plants, energy is produced by a process called as photosynthesis (Photo mean light; synthesis means production). During photosynthesis, plants absorbs light energy from sun and use it to convert carbon dioxide and water in to chemical energy in the form carbohydrates (Glucose). It occurs in two part process. First, the energy from the sunlight is trapped by the chlorophyll pigments that present in the leaf cells. This energy is used to break the water in to oxygen and hydrogen ions. Hydrogen are used to reduce NADP to form NADPH molecules via light dependent reaction at thylakoid membrane. ATP is also synthesized by ATP synthase of thylakoid membrane. The reaction of light dependent reaction is shown below.

2 H2O + 3 ADP + 2 NADP+ +3 Pi + light → 3 ATP + 2 NADPH + 2 H+ + O2

Secondly, NADPH and ATP produced from light reaction provides energy for carbon (CO2) fixation and synthesis of 3-carbon sugar, glyceraldehyde-3-phosphate via light independent reactions (Calvin cycle). Glyceraldehyde-3-phosphate is later used to produce hexose sugars. The reaction for light independent reaction is shown below.

3 CO2 + 9 ATP + 6 NADPH + 6 H+ → Glyceraldehyde-3-phosphate + 9 ADP + 8 Pi + 6 NADP+ + 3 H2O