Nutrition
Nutrition in Plants of Class 7
“Nutrition” is a process of intake as well as utilization of nutrients by an organism. It is the process of breakdown of nutrients into smaller molecules and their absorption. Food provides us nutrition and energy. It contains different types of nutrients in varying amounts according to the need of our body.
Nutrients in animal
These are the substances required by our body for its growth, repair, work and maintenance of the body. Different types of nutrients are carbohydrates, fats, proteins, vitamins, minerals etc. Our daily energy need may vary according to our occupation, age, sex and under some specific conditions.
MODES OF NUTRITION:
There are several modes of nutrition on the basis of which organisms are classified as follows:
Autotrophic (They are able to synthesise their own food.)
1. Heterotrophic(They are not able to synthesise their own food)
Autotrophic
It is a mode of nutrition in which organisms prepare their own food. Inorganic molecules like CO2 and H2O are converted into organic molecules like carbohydrates in the presence of sunlight and chlorophyll.
E.g. Green plants. Autotrophs are further categorized as:
- Photoautotrophs:Those which utilize sunlight for preparing their food e.g. green plants.
- Chemoautotrophs: Those which utilize chemical energy for preparing their food, e.g. Purple sulphur bacteria.
Heterotrophic
It is a mode of nutrition in which organisms derive their food from some other animals or plants. They cannot prepare their own food e.g. Human being. Heterotrophs are further categorized depending on the nature of food they consume:
- Herbivores: Animals which eat only plants,e.g. Cow, Goat etc.
- Carnivores: They feed on flesh of other animals, e.g. Lion, Vulture etc.
- Omnivores: They feed on plants and animals both, e.g. Dog, Human etc.
- Detritivores: Feed on detritus or dead organic remains, e.g. Earthworm etc.
- Sanguivores: Feed on blood, e.g. Leech, Female mosquito etc.
- Frugivores: Feed on fruits, e.g. Parrot etc.
- Insectivores: Feed on insects, e.g. Bats etc.
Differences between autotrophic and heterotrophic organisms
| Autotrophic organisms | Heterotrophic organisms |
| (a) They consist of a green pigment called chlorophyll. | (a) They do not have chlorophyll. |
| (b) They can prepare their own food materials from water and carbondioxide in the presence of light | (b)They cannot prepare their own food materials |
| (c) They release oxygen in the process of photosynthesis. | (c) Oxygen is taken in for respiration. |
| (d) Generally these organisms cannot move from place to place | (d)Generally these organisms exhibit locomotion. |
On the Basis of Mode of Feeding Organisms are Categorised as:
(i) Holozoic: They ingest mostly solid but sometimes liquid food. e.g., Amoeba, Human etc.
(ii) Saprotrophic: They absorb organic matter from dead and decaying organisms with the help of their enzymes. e.g., Bacteria, Fungi etc.
Parasitic:
They derive their nutrition from other living plants or animals,
E.g. Plasmodium, Round worm etc.
