Notes-Class 7-General Science-Chapter-4-Nutrition in Living Organisms-Mah-Board

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Nutrition in plants :

(1) Autotrophic plants : Those organisms that produce their own food are autotrophic. e.g., Plants.

(2) Photosynthesis :

(i) Photosynthesis is the process performed by the plants with the help of sunlight and chlorophyll by using water and nutrients from the soil and carbon dioxide from the air, in which own food is synthesized.

(ii) Chemical equations for photosynthesis :[/responsivevoice]

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(iii) Energy is transformed in process of photosynthesis. Light energy of sun is converted into chemical energy which is stored in the form of food.

(iv) Roots absorb water, minerals and salts from the soil. Stem transports these materials up to the leaves. Carbon dioxide from the air is taken inside from the stomata on the leaves.

(v) In the leaves there are chloroplasts which contain chlorophyll, which absorbs sunlight, and helps in the conversion of carbon dioxide and water into food.

(vi) In the process of photosynthesis oxygen is given out.

(vii) The green parts of the plants that have chlorophyll perform photosynthesis. [/responsivevoice]

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(3) Transport system in plants :

(1) The types of transport system : (a) Xylem (b) Phloem

(a) Function of xylem : Transport of minerals and water from the roots to all aerial parts of the plant.

(b) Function of phloem : Transport of the prepared food i.e. glucose, etc, from the leaves to other parts of the plant. This food is either consumed or stored in different parts of the plant.

(2) Plants do not have separate digestive or excretory system. [/responsivevoice]

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(4) Nitrogen fixation :

(1) Gaseous nitrogen is present in air, But plants cannot take up gaseous nitrogen It is therefore converted into nitrogen compounds, This is known as nitrogen fixation.

(2) Nitrogen fixation is of two types; (a) Biological nitrogen fixation (b) Atmospheric nitrogen fixation.

(a) Biological fixation of nitrogen :

(i) When nitrogen fixation is done by the microbes present in the soil the it is known as biological nitrogen fixation.

(ii) There are two species of microbes Performing nitrogen fixation viz. Rhizobium and Azotobacter.

(iii) Rhizobium microbes are seen in the root-nodules of leguminous plants. They absorb atmospheric nitrogen and convert it into its compound called nitrates.

(iv) Azotobacter microbes are present in sail. They also convert atmospheric nitrogen into nitrates.

(b) Atmospheric fixation of nitrogen :

(i) Lightning at the time of rainy season causes chemical reaction between atmospheric nitrogen and oxygen. This forms nitric oxide (NO)

(ii) Nitric oxide again oxidizes to form nitrogen dioxide (NO₂ )

(iii) This nitrogen dioxide dissolves in rainwater to from nitric acid (HNO₃)

(iv) Nitric acid is added to the soil along with the rain-water. [/responsivevoice]

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(5) Symbiotic nutrition : When two or more than two different types of plants live together to fulfill their needs such as nutrition, protection, support. Etc. with each others’ help, then it is known as symbiotic nutrition. e.g. Lichen

(6) Heterotrophic plants:

Heterotrophic plants - Plants that do not contain chlorophyll are heterotrophy

They grow on or in the other plant body for obtaining food. They are insectiverous,

saprophytic or parasitic. e.g. Loranthus, cuscuta, etc. are parasific plants. thriving on

the host plants.

(7) Insectivorous plants -

(1) Insectivorous plants feed Upon insects to obtain nutrients.

(2) Such plants are generally in soil or water that ts deficient nm nitrogen compounds

e.g. Drosera and Pitcher plant

(8) Saprophytic plants :

(1) Saprophytic plants obtain the food from dead and decaying bodies of other organisms.

(2) Some fungi spoil the food. Some are disease causing while some have medicinal properties,

(3) Useful fungi : Yeast and few mushrooms. In fermentation processes and bread making yeast is used. Some mushrooms are used as food because they are rich  source of iron and vitamins. [/responsivevoice]

1 (NB. Always remember : Fungi are not plants. They are saprotrophic and hence they are placed in separate kingdom.)

(9) Role of nutrients and effects of their deficiency of plants

 

Nutrient	Function	Effects of deficiency
Nitrogen	Important component of proteins chlorophyll and cytoplasm.	Retarded/stunted growth, yellowing of leaves.
Phosphorus	Conversion of light energy into chemical energy.	Early leaf-fall, late flowering, slow growth of roots
Potassium	Necessary for metabolic activities	Weak stem, wilting of leaves, failure to produce carbohydrates.
Magnesium	Production of chlorophyll	Slow/retarded growth, yellowing of leaves
Iron	Production of chlorophyll	yellowing of leaves
Manganese	Production of main plant hormones	Retarded growth, spotted leaves.
Zinc	Production of hormones and their intermediates	Retarded growth, yellowing of leaves

(1) How do plants produce their own food?

Ans : Plants prepare their own food by the process of photosynthesis.

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Nutrition in animals :

1) Three factors involved in nutrition in animals are need for nutrients, mode of ingestion and its use in the body.

2) Nutrients are obtained from food. All the life processes run efficiently due to nutrients

The circulating blood supplies the nutrients to all the parts of the body.

3) For this purpose. the food is converted into soluble forms by an elaborate process

These five steps that occur in nutrition are as follows:

Steps in nutrition :

(1) Ingestion ; Intake of food into the body.

(2) Digestion : Conversion of complex food into simple soluble form.

(3) Absorption : Taking in of soluble nutrients into the blood.

(4) Assimilation : Production of energy through the absorbed nutrients. Also carrying out growth and repair processes through nutrients.

(5) Egestion : Removal of undigested food and unwanted waste products from body. [/responsivevoice]

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Holozoic nutrition :

(1) In unicellular organisms like Amoeba, Euglena, Paramoecium all the processes of nutrition occur in the same cell.

(2) Multicellular animals ingest the food through mouth.

• Insects like cockroach and grasshopper and Nibbling insects — jaw-like mouth-parts
• Butterflies —» tube-like proboscis for sucking the food
• Mosquitoes and bedbugs —> needle-like mouth part for piercing and a tube-like mouth part for sucking the blood and fluids.

6. Types of animals according to the type of food :

(1) Herbivores : Animals that feed on plant matter such as grass fruits, seeds etc.

e.g. grazing animals, granivores . gramnivores (seed-eaters), frugivores (fruit-eaters)

(2) Carnivores : Animals that feed on other animals for their food. Carnivores depend

on herbivores for their food and thus are indirectly dependent on plant matter for the

food. e.g. Animals feeding on herbivores (predators), animals that feed on insects

(insectivores).

(3) Ounivores : Animals feeding on both plants and animals

e.g.human, monkey, chimpanzee etc.

(4) Scavengers : Scavengers obtain their food from dead bodies of animals, e.g. vulture, crow, hyena, etc. [/responsivevoice]

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Decomposers :

Some microbes decompose the dead and decaying organic matter and convert it back to inorganic compounds by decomposition process Decomposers clean and conserve the environment while feeding.

7. saprozoic nutrition : In saprozoic nutrition, animals decompose the dead and decaying organic matter and utilize it as the food.

e.g. the insects, unicellular animals, house flies, ants, spiders. [/responsivevoice]

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Parasitic Nutrition :

(1) Parasitic nutrition is seen in some animals. The dependent animal is said to be a parasite while the animal from which parasite obtains the food is called a host.

(2) Parasite dose not survive without a host. Therefore it will not kill the host as in case of prey and predator relationship.

(3) Parasites are mainly of two types : Ectoparasites and endoparasites.

(a) Ectoparasitic nutrition : In this type the parasites are seen living on the body surface of the host and obtaining food by sucking the blood or body juices. e.g. louse, bed-bug, tick

b) Endoparasitic nutrition : In this type the parasites live inside the body of a host. They consume the ready-made digveted food from host. e.g. tapeworm and roundworm. [/responsivevoice]

(1) Have you seen small animals on the bodies of animals like dogs and buffaloes? Which are those small animals? 

 Ans. Yes. On the bodies of pet animals there are parasitic organisms like flea, ticks and mites. Sometimes leeches are also seen.

(2) From where do these little animals obtain their food?

Ans. These parasites obtain blood from their host animals.

(3) From where do the warms in the intestine obtain their food?

Ans. The digested food having useful nutrients in the host intestine is taken by the

worms living inside the intestine of the host.