The process of intake of source of energy or material inside the body and absorption of nutrients from it is called as NUTRITION.
Every living organism need a source of energy for performing daily activities and the source of energy is Food.
All living organisms depends on same source of energy, but difference is in how they fulfill this.
Some organisms use simple food as source of energy and obtaining it from inorganic compounds like CO2 and H2O, they are called as Autotrophs.
While other organisms use complex food and breakdown them to simple form, they are called as Heterotrophs.
Nutrition is of two main types:
Autotrophic Nutrition:
The process of intake of inorganic molecules as source of energy and obtain simple food from it is called as Autotrophic Nutrition.
Examples: In Green Plants and Bacteria.
The carbon and energy requirement of plants are fulfilled by the process of Photosynthesis.
The process by which living organisms take in substances from the outside and convert them into stored forms of energy is called as Photosynthesis.
Photosynthesis converts CO2 and H2O in presence of sunlight and chlorophyll into carbohydrates.
The carbohydrates which are not used immediately are stored in the form of starch.
Events in Photosynthesis:
1. Absorption of Light Energy by chlorophyll.
2. Conversion of Light Energy to Chemical Energy.
3. Reduction CO2 into carbohydrates.
It is not necessary that the pattern of above events remains same.
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.
Plant takes water from root and carbon dioxide from atmosphere.
Plants obtain carbon dioxide via some pores present in the leaves called as Stomata
What are Stomata?
Tiny pores present in the plants are called as Stomata.
FUNCTION: Gaseous Exchange and Transpiration. The opening and closing of the pore is a function of the guard cells.
LOCATION: In Leaves, Stem and roots of the plant.
STRUCTURE:
They comprise of a pair of Guard cells surrounded by epidermal cells.
Guard cells comprise of many chloroplasts and a nucleus.
Stomata opens when it swells by absorbing water and takes up carbon dioxide for photosynthesis.
When large amounts of water lost by the stomata, the plant closes these pores when it does not need carbon dioxide for photosynthesis.
Heterotrophic Nutrition:
The process of intake of complex food as source of energy and obtain nutrition from it is called as Heterotrophic Nutrition.
Examples: In animals and fungi.
This form of nutrition differs depending on the type and availability of food material.
Source of Food can be Mobile or Stationary
Breakdown of food can be Outside or Inside living organism.
In some organism the food breaks down inside the body as in Humans.
In others the food breaks down outside the body as in Fungi-Bread Mould, Yeast and Mushrooms.
Some other organisms derive nutrition from plants or animals without killing them.
This is parasitic nutrition. In Cuscuta (Amar-bel), ticks, lice, leeches and tapeworms.
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