Nutrition in Plants, Biology tutorial


Nutrition is the basic means of intake of food by the organism and its utilization by the body. All organisms necessitate food to perform their life processes. Food includes of various nutrients which comprise proteins, carbohydrates, fats, vitamins and minerals. Food gives us energy to nurture, repair the harmed parts in our body.

Plants get their nutrition by different modes. The mode of nutrition in plants can be heterotrophic as well as autotrophic mode. Plants can be categorized into heterotrophs and autotrophs.

i) Autotrophic plants can synthesize or prepare their own food by the method of photosynthesis.

ii) Heterotrophic plants can't synthesize or prepare food on their own however depend on other organisms for their nutrition. These plants can be further categorized into parasites, saprophytes and symbiotic plants.

Autotrophic form of nutrition - Photosynthesis

This is an autotrophic form of nutrition. Photosynthesis is a procedure through which green plants can synthesize glucose by using raw materials such as carbon-dioxide and water in the presence of chlorophyll and sunlight. Photosynthesis includes the conversion of solar energy into chemical energy to synthesize or prepare starch.

Heterotrophic form of nutrition:

Heterotrophic plants don't have chlorophyll. Thus, they can't produce their own food by using the procedure of photosynthesis. Heterotrophic plants get food from other plants by following either a parasitic, saprophytic or symbiotic form.

i) Parasitic mode

ii) Insectivorous mode

iii) Saprophytic mode

iv) Symbiotic mode

Resources and conditions essential for Photosynthesis:

For the process of photosynthesis to occur, certain resources or conditions should be available. These are carbon-dioxide, chlorophyll, sunlight, water, mineral salt, appropriate temperature and enzymes.

1) Carbon-dioxide:

Carbon-dioxide is derived from the environment and it diffuses into the intercellular spaces via the stomata of the leaves. By employing the intercellular spaces, carbon-dioxide diffuses further into the mesophyll cells having chloroplast.

2) Water and Mineral salts:

Water and mineral salts are obtained from the soil. They pass into the roots of plants via the root hairs by a procedure termed Osmosis. Water and dissolved mineral salts are conducted through xylem from the roots via the stem and at last to the mesophyll cells having chlorophyll of the leaves.

3) Sunlight:

Sunlight is acquired from the solar energy. The light from the sun is entrapped by the chlorophyll of the leaves. The sunlight is employed to divide water into hydrogen ion and hydroxyl ion in a process termed as Photolysis.

4) Optimum Temperature:

Temperature is obtained partially from the solar energy and partially from chemical reactions in the leaves throughout which heat is produced. Appropriate temperature is significant for enzymes to facilitate them function appropriately throughout photosynthesis.

5) Chlorophyll:

Chlorophyll is the green coloring pigment obtained in the palisade and spongy mesophyll of the leaves. The chlorophyll exhibits sites where food can be prepared and it aids to entrap solar energy and transform it to the chemical energy.

Importance of Photosynthesis:

Photosynthesis is extremely significant both to plants and animals for the given reasons.

a) Production of Food: It gives food for both plants and animals. All green plants are capable to prepare their food via the procedure of photosynthesis whereas animals based directly or obliquely on the green plant for their food.

b) Purification of the Atmosphere: Waste products such as carbon-dioxide released throughout respiration by both plants and animals are eliminated from the atmosphere by plants for use throughout photosynthesis.

c) Discharge of Oxygen to the Environment: Oxygen required for respiration by plants and animals is discharged into the environment throughout photosynthesis.

d) It serves up as building blocks for other substance: Photosynthesis gives the building block or carbon skeleton on which other food substances like proteins, fats, oil and so on are built.

Mineral necessities of Plants:

Plants necessitate mineral nutrients or element acquired from the soil in the form of solution for excellent growth and healthy progress. The soil is the major source of the mineral salts whereas gaseous elements like oxygen, hydrogen and carbon are mostly getting from the atmosphere. Such elements or plants nutrients are classified into two groups, based on the quantity that is requisite by plants. They are:

(i) Macro-nutrients or Major elements: Macro-nutrients are the mineral elements or nutrients needed in big quantities for healthy growth of plants. Illustrations comprise nitrogen, phosphorus, magnesium, potassium, calcium, hydrogen, oxygen, carbon, sulphur and iron.

(ii) Micro-elements or Trace elements: Micro-nutrients are the mineral elements or nutrients needed in small amounts for healthy growth of plants. Illustrations comprise zinc, boron, copper, cobalt, molybdenum, chlorine and manganese.

Nitrogen Cycle:

Lightning counters with nitrogen gas in the atmosphere to form nitrogen dioxide. This nitrogen dioxide (NO2) is then partially dissolved in water throughout rainfall to make nitric acid. If the rainfall strikes the ground, nitrates are made which are then absorbed through the roots of plants.

Nitrogen fixing bacteria (which are present on the root nodules of the leguminous plants) transforms nitrogen in the atmosphere to ammonium salts via a procedure termed ammonification. The Ammonification is as well completed by decomposers (that is, saprophytes) which transform dead plants and animals and also faecal material into ammonium salts. The ammonium salts are then transformed into nitrates through nitrifying bacteria. This procedure is termed as nitrification.

A few amounts of nitrates which are present in the soil are absorbed by plants. Such nitrates in the plants are eaten by animals. The animals in turn discharge faecal matter and finally die and decompose, returning nitrates to the soil. The adding up of fertilizers to the soil as well generates soil nitrates.

The nitrates in the soil can as well be transformed into nitrogen gas by denitrifying bacteria present in the soil. This procedure is termed as Denitrification. The nitrogen is then returned to the environment and the cycle carries on.

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