Synthesis of Food in Green Plants:

Green plants have the unique ability to synthesize their own food through a process called photosynthesis. This process involves the conversion of light energy from the sun into chemical energy, which is stored in the form of glucose. The synthesis of food in green plants is crucial for their survival and serves as the primary source of energy for all living organisms on Earth.

Process of Photosynthesis:

Photosynthesis can be divided into two stages: light-dependent reactions and light-independent reactions.

1. Light-Dependent Reactions:
- These reactions occur in the thylakoid membranes of the chloroplasts.
- Chlorophyll, the green pigment found in chloroplasts, captures light energy from the sun.
- This light energy is then used to split water molecules into hydrogen ions (H+), oxygen (O2), and electrons (e-).
- The electrons are transferred along an electron transport chain, releasing energy in the process.
- This energy is used to produce ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which are energy carriers.

2. Light-Independent Reactions (Calvin Cycle):
- These reactions occur in the stroma of the chloroplasts.
- The ATP and NADPH generated in the light-dependent reactions are used to convert carbon dioxide (CO2) into glucose through a series of enzyme-controlled reactions.
- This process is known as the Calvin cycle.
- The carbon dioxide combines with a five-carbon molecule called RuBP (ribulose bisphosphate) to form a six-carbon compound.
- This compound is then converted into two molecules of a three-carbon compound called PGA (phosphoglyceric acid).
- PGA is then converted into PGAL (phosphoglyceraldehyde) using ATP and NADPH as energy sources.
- Some PGAL molecules are used to regenerate RuBP, while others are combined to form glucose.

Importance of Photosynthesis:
- Photosynthesis is essential for the survival of green plants as it provides them with the energy they need to carry out their metabolic processes.
- It also plays a vital role in maintaining the oxygen and carbon dioxide balance in the atmosphere.
- The glucose produced during photosynthesis serves as a source of energy for all living organisms, either directly or indirectly.
- Additionally, photosynthesis is responsible for the production of other organic compounds such as amino acids, lipids, and nucleic acids, which are necessary for plant growth and development.

In conclusion, the process of photosynthesis in green plants involves the conversion of light energy into chemical energy, which is used to synthesize glucose and other organic compounds. This process is essential for the survival of green plants and provides the basis for the entire food chain.

Leaves have a green pigment called chlorophyll. in presence of sunlight, they use carbon dioxide and water to synthesis carbohydrates. during this process oxygen is released. the carbohydrates ultimately get converted into starch.
Carbon dioxide from air os taken through stomata. water and mineral are absorbed by roots and transported to leaves.