Autotrophic nutrition is a type of nutrition in which organism synthesize food from inorganic source by the process of photosynthesis.
Raw materials required to prepare food are simple organic materials from the environment such as carbon dioxide and water in presence of sunlight.
Green plants and certain bacteria like blue green algae which have chlorophyll have autographing nutrition.
Autographs are the producers in the food chain.
They store the food in the form of starch.
The process in which plant make their own food in the presence of sunlight is called photosynthesis.
6CO2 + 12H2O ————– C6H12O6 + 6H2O + 6O2
EVENT OCCURING DURING PHOTOSYNTHESIS
Absorption of light energy by chlorophyll.
Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
Reduction of carbon dioxide to carbohydrates.
These steps need not take place one after the other immediately. For example, desert plants take up carbon dioxide at night and prepare an intermediate which is acted upon by the energy absorbed by the chlorophyll during the day.
FUNCTION OF CHLOROPHYLL
Chlorophyll is a pigment present in cell organelles called plastid, which lies just below the upper epidermis in a tissue called palisade. It is a photo protector molecule. Chlorophyll absorb mostly the blue and red regions of spectrum
EXCHANGE OF GASES IN PLANTS
Gaseous exchange takes place in the leaves through stomach which are tiny pores present on the surface of the leaves. The exchange of gases occurs across the surface of stems,roots and leaves as well. The opening and closing of the pore is a function of the guard cell. The guard cells swell when water flows into them,causing the stomatal pore to open.
RAW MATERIALS FOR PHOTOSYNTHESIS
Water used in photosynthesis is taken up from the soil by the roots in terrestrial plants.
CO2 is obtained by plants through stomata in leaves .
Other materials like nitrogen, phosphorus, iron and magnesium are taken up from the soil.