B Bharati Public School, Navi Mumbai

Subject: Biology Session:2020-21

Class: X Topic: Life Processes- Part 1(Nutrition)

Subtopics: 1. Nutrition in Plants 2. Nutrition in Amoeba 3. Nutrition in Human

Beings

Life Processes All the processes which together keep the living organisms alive and perform the job of maintaining of the body are called life processes.

For Example: Nutrition, respiration, transportation, Excretion

Modes of Nutrition Autotrophic Nutrition

• organism produces their food from the simple inorganic materials such as water, carbon dioxide and mineral salts in the presence of sunlight by the method of photosynthesis.

• Example: All green plants

Heterotrophic Nutrition

• organisms depend upon other organisms for food to survive. It is of three types – saprophytic, parasitic and holozoic.

• Example: All insects, birds and animals

Autotrophic nutrition

Photosynthesis Three main events during photosynthesis: (i) Absorption of light energy by chlorophyll. (ii) Conversion of light energy to chemical energy and

splitting of water molecules into hydrogen and oxygen. (iii) Reduction of carbon dioxide to Carbohydrates

Chemical Equation of Photosynthesis

Cross-section of a leaf Notice that some

cells contain green

dots.

These green dots

are cell organelles

called chloroplasts

which contain chlorophyll.

Mechanism of opening and closing of stomata

The opening and closing of the pore is a function of the guard cells.

The guard cells swell when water flows into them, causing

the stomatal pore to open.

Similarly the pore closes if the guard cells shrink.

Heterotrophic Nutrition Saprophytic nutrition:

• organisms break-down the food

material outside the body and then absorb it.

• Examples are fungi like bread moulds, yeast and mushrooms.

Parasitic Nutrition

• organisms derive nutrition from plants or animals without killing them.

• Examples are cuscuta (amar-bel), orchids, ticks, lice, leeches and tape-worms.

Holozoic nutrition

• Some organisms take in whole material and break it down inside their bodies. What can be taken in and broken down depends on the body design and functioning.

Example: Amoeba, Human • Holozoic nutrition involves five steps: i. Ingestion ii. Digestion iii. Absorption iv. Assimilation v. Egestion

Nutrition in Amoeba

1.Ingestion: Amoeba engulfs food by temporary finger-like projections of its

body surface called pseudopodia. When a pseudopodium fuses with the food particle, it forms a food vacuole.

2. Digestion: Complex substances are broken down into simple substances inside the food vacuole.

3. Absorption: These simple substances are then diffused into the cytoplasm. 4. Assimilation: The absorbed food will be utilized to carry on various

functioning of the body. 5.Egestion: The remaining unwanted material is taken to the cell surface and

is thrown out.

Nutrition in Human Beings

• Digestion of food in humans takes place in the alimentary canal which is basically a long tube extending from the mouth to the anus

• Alimentary gland is connected with two glands: Liver & Pancreas

Parts of Alimentary canal

1. Mouth: i. crushing the food with our teeth. ii. saliva secreted by the salivary glands makes the food wet and its

passage smooth. iii. The food is mixed thoroughly with saliva and moved around the

mouth while chewing by the muscular tongue. iv. The saliva contains an enzyme called salivary amylase that breaks

down starch which is a complex molecule to give sugar 2. Oesophagus: i. It is the food pipe that takes food from mouth to stomach ii. The lining of canal has muscles that contract rhythmically in order

to push the food forward. These peristaltic movements occur all along the gut.

Parts of Alimentary canal(contd.) 3. Stomach: i. The gastric glands release

hydrochloric acid, a protein digesting enzyme called pepsin, and mucus.

ii. The hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin.

iii. The mucus protects the inner lining of the stomach from the action of the acid under normal conditions.

4. Sphincter muscle: It regulates exit of food from the stomach in small amounts into the small intestine.

Parts of Alimentary canal(contd.)

5. Small Intestine: It secretes intestinal juice containing enzymes which finally convert:

i. Carbohydrates into glucose

ii. Proteins into amino acids

iii. Fats into fatty acids and glycerol

1. Liver

Two glands in the human digestive system

a) It secretes Bile juice which makes the medium alkaline.

b) Bile salts act on large fat globules and breaks them down into smaller globules increasing the efficiency of enzyme action. This is similar to the emulsifying action of soaps on dirt.

2. Pancreas: It secretes pancreatic juice which contains enzymes: i. Trypsin- digests protein ii. Amylase- digests carbohydrates iii. Lipase- digests lipids

Absorption of food

• The inner lining of the small intestine has numerous finger-like projections called villi which increase the surface area for absorption.

• The villi are richly supplied with blood vessels which take the absorbed food to each and every cell of the body, where it is utilised for obtaining energy, building up new tissues and the repair of old tissues.

Parts of Alimentary canal(contd.)

6. Large Intestine: i. The unabsorbed food is

sent into the large intestine where more villi absorb water from this material.

ii. The rest of the material is removed from the body via the anus.

iii. The exit of this waste material is regulated by the anal sphincter.

Let us Recapitulate....

• The maintenance of life requires processes like nutrition,

respiration, transport of materials within the body and excretion of waste products.

• „ Autotrophic nutrition involves the intake of simple inorganic materials from the environment and using an external energy source like the Sun to synthesise complex high-energy organic material.

• „ Heterotrophic nutrition involves the intake of complex material prepared by other organisms. „

• In human beings, the food eaten is broken down by various steps along the alimentary canal and the digested food is absorbed in the small intestine to be sent to all cells in the body.

Links

• https://www.youtube.com/watch?v=A3BXU9_6ceY

• https://www.youtube.com/watch?v=xLcnqMvlj7c

Assignment-1

1. What are the differences between autotrophic nutrition and heterotrophic nutrition?

2. Where do plants get each of the raw materials required for photosynthesis?

3. What is the role of the acid in our stomach?

4. What is the function of digestive enzymes?

5. How is the small intestine designed to absorb digested food?