NUTRITION IN PLANTS- CLASS 07 - BEST NOTES

              NUTRITION IN PLANTS 

Nutrition is the process of taking food by an organism and digestion absorption and utilisation by the body.

Modes of nutrition 

1. Autotrophic mode of nutrition 

• The word 'auto' self and 'tropic' means nutrition. Thus, autotrophic means 'self  nutrition'.
• The mode of nutrition in which an organism makes its own food from simple substances like carbon dioxide water and minerals present in the surrounding School autotrophic nutrition and that organism is called autotrophs.
• All green plants and some bacteria prepare their own food by autotrophic mode of nutrition  thus, they are autotroph.

2. Hetrotrophic mode of nutrition 

• The word 'hetros' means other and 'trophos' means nutrition . Thus,  hetrotrophic   means nutrition' obtained from other'.
• The mode of nutrition in which an organism can not make its own food from the simple substances that obtains ready made food made by Green plants directly or indirectly is called heterotrophic nutrition and that organism is called heterotroph.
• Animals and non green plants at topic mode of nutrition and are called heterotrophs.

PHOTOSYNTHESIS

• Green plants are autotrophs and make their own food the process of photosynthesis.
• The term photosynthesis was given by Charles Reid Barnes in 1893.
• 'Photo' means ' light' and ' synthesis' means 'to build'. Thus,  photosynthesis means 'building up by light'.
• The leaves of a plant are green because they contain time in green colour body is called chloroplast which contain a green pigment call chlorophyll.
• The chlorophyll is the solar energy to prepare food from carbon dioxide and water.
• The process by which green plants make their own food from carbon dioxide and water by using solar energy in presence of chlorophyll is called photosynthesis.
• Oxygen gas is released during photosynthesis.
• The food prepared by the Green Leaves of a plant is in the form of simple sugar called glucose.
• This glucose synthesized in the leaves is then transported to the different parts of the plant as a cross by the phloem . The extra glucose is changed into a complex carbohydrate called starch. This starch is stored in leaves and other parts of the plant.

REQUIREMENTS FOR PHOTOSYNTHESIS 

1.  Water and minerals - water and Minerals are absorbed by the roots of the plant from the soil through the process of osmosis. Water and Minerals are transported to the leaves and other parts of the plant by xylem vessels which runs like pipe throughout the root ,stem branches and leaves.
2. Carbon dioxide - The green plant take  carbon dioxide gas from the air for carrying out photosynthesis . Tiny pores called stomata are present on the underside of the leaves surrounded by guard cells which control the opening and closing of stomata. The carbon dioxide gas enters the leaves of the plant through the stomata.
3. Chlorophyll - chlorophyll is a green pigment present in the cell organelle cal chloroplast. The green colour of the plants is due to the presence of chlorophyll in them. Chlorophyll is present mostly in the Green Leaves of the plants. Chlorophyll trap the Solar Energy. The energy is used to synthesise food from carbon dioxide and water during the process of photosynthesis. Beside leaves photosynthesis also takes place in other green parts of the plants like green stems and green branches. For example in desert plants like cactus, the leaves are modified into spines to reduce water loss by transpiration. These plants have thick and flashy green stem which carry out the process of photosynthesis to make their food.
4. Sunlight - Green plants synthesise food in the presence of Sunlight. Chlorophyll present in green leaf trap the Solar Energy. The solar energy is converted into chemical energy by the process of photosynthesis. The chemical energy stored in the form of carbohydrate in plant. Leaves of plants grow in different patterns so as to catch the maximum amount of Sunlight.

Aquatic plants like hydrilla, water lily and vallisneria take in carbon dioxide dissolve in water to prepare their food and they give out oxygen during this process.

Importance of photosynthesis

• Photosynthesis in higher plants are green plants to make their own food. In the absence of photosynthesis there would not be any plant.
• The survival of all animals in the world directly or indirectly depends upon the food made by the plants.
• Oxygen which is essential for the survival of all living organism is produced during photosynthesis. Carbon dioxide is used by the plants during photosynthesis . So we can say that photosynthesis maintain the balance between Oxygen and Carbon dioxide in the atmosphere.
• So in essence of photosynthesis life on the earth would be impossible.

Heterotrophic mode of nutrition

1. Saprotrophic nutrition- Some non green plants obtain their nutrients from the dead and decaying organic matter of plants and animals . Such plants are usually white in colour and have no leaves at all.                                                            The mode of nutrition in which non green plants obtain their nutrients from dead and decaying organic matter of plants and animals is called saprotrophic nutrition . Plants which use saprotrophic mode of nutrition are called saprophytes.                                 Example ,Indian Pipe and Coral root.
2. Parasitic nutrition- cuscuta is a non green plant. It does not have chlorophyll. It cannot make its own food. Its long yellow thread like stems and around the stem and branches of the tree on which it climbs. It has a special structure called haustoria which fits into the plant body on which it climbs for absorption of readymade food.                   The mode of nutrition in which some plants leaves or in the body of other living organisms and their right there ready made food from them is called parasitic nutrition the plant which obtain the ready made food is called parasite and the organism from whose body the food is obtained is called host.                                                      Parasite may be total or partial. Kutta the total parasite. A few  fungi and bacteria also total parasite.
3. Symbiosis - The Association in which two different types of organisms live and work together for their mutual benefits call Symbiosis. Lichens show symbiotic relationship or Symbiosis.                            Similarly rhizobium bacteria lives in the nodules of the route of ledger Mini implants and provide the nitrogen in a soluble form and return the plant provide food and shelter to the rhizobium bacteria. So both organisms benefit each other.

Special mode of nutrition

A few plants feed on insects for fulfilling their Network and requirement. Sach insect eating plants are called insectivorous plants. Pitcher plant Venus flytrap there are some examples of it.

      In a Pitcher plant the leaf lamina is modified To Hamen picture like structure. The effects of the leaf is modified into a lead which can open and close the mouth of the pictures. Inside the pitcher there are here which are directed downward force stop when an insect lands on the picture the lead closes and attract insects get entangled in the hair fall stop the insect is digested by the digestive juice secreted in the Pitcher plant.

Replenishment of nutrients in the soil

Plant absorb the mineral nutrients is specially nitrogen from the soil. Therefore there is a depletion of Nitrogen in the soil over a period of time. 

Manure and fertilizers used to replenish the nutrients in the soil. These manure and fertilizers contain nutrients such as nitrogen potassium and phosphorus needed by the plants for their healthy growth. These nutrients need to be added from time to time to enrich the soil.

 Rhizobium bacteria living in an audience of the roots of leguminous plants and reached the soil with nitrogen. This is a natural way of replenished in the soil with nitrogen.