Nutrition in human

Neutron in human being 

Nutrition in human ,nutrition

When we walk or ride a bicycle, we are using up energy. Even when we are not doing any apparent activity, energy is needed to maintain a state of order in our body.

We also need material from outside in order to grow, develop, synthesise protein and other substances needed in rue body. This source of energy and materials is the food we eat.

How does living thing get their food?

The general requirement for energy and materials is common in all organisms, but it is fulfilled in different ways. Some organisms use simple food material obtained from an inorganic source in the form of carbon dioxide and water. these organisms or autotrophs include green plants and some bacteria.

Other organisms utilise complex substances. These complex substances have to be broken down into simpler ones before they can be used for the upkeep and growth of the body. 

To achieve this, organisms use bio-catalysts called enzymes. Thus the heterotrophs survival depends directly or indirectly on autotrophs. Such heterotrophic organisms include animals and fungi.

Carbon and energy requirements of the autotrophic organisms are fulfilled by photosynthesis. Quite simply it is the process by which autotrophs take in substances from the outside and convert them into the stored form of energy.

This material is taken in the form of carbon dioxide and water which is converted into carbohydrates in the presence of sunlight and chlorophyll. Carbohydrates are utilised for providing energy to the plant. A somewhat similar situation is seen in us where some of the energy derived from the food we eat is stored in our body in the form of glycogen.

Let us now see what actually happens during the process of photosynthesis.

The following event occurs during this process:-

i) Absorption of light energy by chlorophyll.

ii) conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.

iii) 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.

If you carefully observe a cross-section of a leaf under the microscope you will notice that some cell content green dots. The green dots are cell organelles called chloroplasts which contain chlorophyll. Let us do an activity which demonstrates that chlorophyll is essential for photosynthesis.

We had talked about stomata which are tiny pores present on the surface of the leaves. Massive amount of gaseous exchange takes place in the leaves through these pores for the purpose of photosynthesis. But it is important to note here that exchange of gases also occurs across the surface of stems. R roots and leaves as well.

A large amount of water is also lost through these stomata, so the plant close these pores when it does not need carbon dioxide for photosynthesis. The opening and closing of the pore is a function of the guard cells.

So far, we have talked about how autotrophs meet their energy requirements. But they also need other raw materials for building their body. Water used in photosynthesis is taken up from the soil by the roots in terrestrial planets.
Other materials like nitrogen are in essential elements used in the taken up from the soil.

Nitrogen is an essential element used synthesise of protein and other compounds. This is taken up in the form of inorganic nitrates or nitrites. Or it is taken up as organic compounds which have been prepared by bacteria from atmospheric nitrogen.

Heterotrophic Nutrition:-

 Each organism is adapted to its environment. The form of nutrition differs depending on the type and availability of food material as well as how it is obtained by the organism. For example, whether the food source is stationary such as grass or Mobile such as a deer, would allow for differences in how the food is accessed and what is the nutritive apparatus used by a cow and a lion.

There is a range of strategics by which the food is taken in and used by the organism. Some organisms break down the food material outside the body and then absorb it. Example are fungi like bread mould, yeast and mushrooms. Others take in whole material and break it down inside their bodies. What can be taken in and broken down depends on body design and functioning.

What do you think would be differences in animals that eat grass, fruits, insects, fish, or dead rabbits? Some other organisms derive nutrition from plants or animals without killing them. This nutritive strategy is used by a wide variety of organisms like Cuscuta tricks, lice, leeches and tape-worms.

How do organisms obtain their nutrition?

Science the food and the way it is obtained differ. The digestive system is different in various organisms. In a single-celled organism, the food may be taken in by the entire surface. But as the complexity of the organism increase, different part become specialised in performing a different function.

For example, amoeba takes in food using temporary finger-like extensions of the cell surface which fuse over the food particles forming a food vacuole. Inside the food vacuole.

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