life process notes class 10 all chapter
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Explanation:
Nutrition
Nutrition
The process of acquiring food that is needed for nourishment and sustenance of the organism is called nutrition.
There are two main modes of nutrition, autotrophic and heterotrophic.
Heterotrophic nutrition has subtypes as holozoic, saprophytic and parasitic nutrition.
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Autotrophic Nutrition
If an organism can nourish itself by making its own food using sunlight or chemicals such mode of nutrition is called as autotrophic nutrition.
Plants photosynthesize (use light energy) and are called photoautotrophs.
Few bacteria use chemicals to derive energy and are called chemoautotrophs.
Photosynthesis
Photosynthesis is an important process by which food is formed.
The plants make food using sunlight and water, which provides nourishment to other organism and themselves.
Chlorophyll present in the green parts absorbs light energy.
This light energy is used to split water into hydrogen and oxygen.
Hydrogen is then used to reduce carbon dioxide into carbohydrates, typically glucose.
Chlorophyll is essential for photosynthesis and stomata to facilitate intake of carbon dioxide.
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Stomata
Stomata are pores on the leaves that help in exchange of gases.
They are mostly found on the underside of the leaf.
Each stoma is guarded by guard cells, which control the opening and closing of the pore.
The water content of the guard cells is responsible for their function.
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Saprophytic Nutrition
Some organism feed on dead and decaying organic matter. This mode of nutrition is called saprophytic nutrition.
The food is partially digested outside the body and then it is absorbed.
E.g. Fungi are saprophytes.
Parasitic Nutrition
Some organisms feed on the expense of another organism and in turn causing it harm. This is called parasitic mode of nutrition.
These organisms live on the body or in the body of a host organism and derive the nutrients directly from the body of the host.
E.g. Leech is an ectoparasite while Ascaris is an endoparasite. Cuscuta is a parasitic plant.
Nutrition in Amoeba
Amoeba feeds by holozoic mode of nutrition.
It engulfs the food particle using pseudopodia, the process is called phagocytosis.
The engulfed food gets enclosed in a food vacuole.
As the food vacuole passes through the cytoplasm, digestion, absorption and assimilation take place.
When the food vacuole opens to outside, egestion of undigested food takes place.
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Nutrition in Paramoecium
Paramoecium also exhibits holozoic nutrition.
However, they have cilia that help them to engulf the food through the oral groove.
A food vacuole is created enclosing the food.
It moves through the cytoplasm, the process is called cyclosis.
Food digested in the food vacuole is absorbed by the cytoplasm.
Undigested food is given out to a tiny pore called anal pore or cytopyge.
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Nutrition in Humans
Humans are omnivores, they can eat plant-based food as well as animal-based food.
Being more complex, humans have a very complicated nutrition system.
The digestive system has an alimentary canal and associated digestive glands, which together function to nourish the body.
There are five stages in human nutrition; Ingestion, Digestion, Absorption, Assimilation and Egestion.
Four stages i.e. ingestion, digestion, absorption and egestion take place in the alimentary canal while assimilation of food takes place in the whole body.
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Alimentary Canal
Alimentary canal in humans is a long tube of varying diameter.
It starts with the mouth and ends with the anus.
Oesophagus, stomach, small intestine and large intestine are the parts of the alimentary canal.
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