Question

Give all important definitions of the chaper life processes class 10 Biology​

Answer 1

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.

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.

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.

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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