Photosynthesis means synthesis of food with the help of sunlight.
The overall equation of photosynthesis is
Photosynthesis process takes place only in green parts of the plant, mostly in leaves and to lesser extent in green stems or floral parts of the plants.
Leaves of the plant are known as light powered food factories.
A green substance called chlorophyll in the leaves catches the energy from sunlight, water from soil, CO2 from air and completes the chemical form. This process is called photosynthesis.
Chlorophyll pigments are mainly present in cell organelles called plastids (chloroplast).
There are different kinds of chlorophyll molecules present in photosynthesis organisms. In plants mostly there are two kinds viz. chlorophyll a and chlorophyll b. Both chlorophyll a and chlorophyll b are very similar in molecular structure, except that the CH3 group in chlorophyll a is replaced by CHO group in chlorophyll b.
The CO2 for this process comes from air. It seeps into leaf through tiny holes into lower surfaces known as stomata.
Stomata are open during day time and closes during night time.
In addition to sugar, This process also produces oxygen which sleeps out in the air.
It occurs only in visible light region of wavelength 4000-7500°A. The temperature range is from -35°C to +75°C.
It is the only carbon fixing process on earth. The rate is optimum between 10°C to 35°C.
Certain bacteria and algae can also capture light energy and use it to make food e.g. photosynthesis bacteria contains chlorophyll in tiny bodies called chromatophores.
Essential elements in plants are Carbon – 45%, Oxygen – 3%, Hydrogen – 6%, Nitrogen – 13%.