Life Process Part-I

Life Process Part-I Class 10th Science

Topics in the Chapter

• Introduction
• Modes of Nutrition
•Autotrophic Nutrition
→ Raw materials for photosynthesis
→ Site of Photosynthesis
→ Main Events of Photosynthesis
• Stomata
→ Functions of stomata
• Heterotrophic Nutrition
→ How organisms obtain their food
• Nutrition
• Nutrition in Human Beings
→ Human Digestive System

Introduction

→ All living things perform certain life processes like growth, excretion, respiration, circulation etc.

→ All the processes like respiration, digestion, which together keep the living organisms live and perform the job of body maintenance are called life processes.

Modes of Nutrition

• Nutrition in Plants

(i) Plants are autotrophs.
(ii) Make their own food.
(iii) Eat animals for their food.

• Nutrition in Animals

(i) Animals are heterotrophs.
(ii) Depends on plants or other

Autotrophic Nutrition

→ It is a kind of nutrition in which inorganic materials like CO2, water etc. are utilized to prepare organic food by the process of  photosynthesis.
E.g: Green plants.

→ The organisms which carry out autotrophic nutrition are called autotrophs (green plants).

→ Autotrophs use simple inorganic material and convert it into complex high energy molecules (Carbohydrates)

→ Autotrophic nutrition is fulfilled by the process by which autotrophs take in CO2 and H2O and convert these into carbohydrates in the presence of chlorophyll, sunlight is called Photosynthesis.

• Equation for Photosynthesis:

• Raw materials for photosynthesis

→ Sunlight: It is inorganic material.
→ Chlorophyll: Sunlight absorbed by chlorophyll.
→ CO2: Enters through stomata and oxygen (O2) is released as by-product through stomata on leaf.
→ Water: Water + dissolved minerals like nitrogen, phosphorus etc. are taken up by the roots of the soil.

• Site of Photosynthesis

Some cells contain green pigments which are cell organelles called chloroplasts which contain chlorophyll.

• Main Events of Photosynthesis

→ Absorption of light energy by chlorophyll.
→ Conversion of light energy into chemical energy + splitting (breaking) of water into hydrogen and oxygen.
→ Reduction of CO2 to carbohydrates.

Stomata

Stomata are the tiny pores present on the surface of the leaves.

• Functions of stomata

→ Exchange of gases O2/CO2.

→ Loses large amount of water (water vapour) during transpiration.

Heterotrophic Nutrition

→ Kind of nutrition in which organisms do not possess the ability to synthesize their own food. They depend on autotrophs for their food supply directly or indirectly.
Example: Animals, fungi.

→ Holozoic Nutrition: Animals take in solid food and breakdown inside the body.
Example: Amoeba, animals.

→ Saprophytic Nutrition: Organisms feed on dead, decaying matter.
Example: Fungi.

→ Parasitic Nutrition: Parasites live inside or outside other organism (host) and derive nutrition from it.

Example: Cuscuta (plant parasites), Ticks etc.

 • How organisms obtain their food

→ Unicellular/Single celled organisms: Food is taken up through entire surface.
Example: Amoeba, Paramaecium

→ Paramaecium: Cilia (Present all over the body) → Take in food → At a specific spot 

Nutrition

Different organisms utilize different nutritional processes as it depends upon the source of carbon from where the food is taken.

Nutrition in Human Beings

→ The alimentary canal is basically a long tube extending from the mouth to the anus. Various regions are specialised to perform different functions.

• Human Digestive System

(i) Mouth: Intake of whole food.

(ii) Teeth: Chewing/grinding of food.

(iii) Tongue: Rolling of food + Tasting of food + Swallowing/Pushing down of the food.

(iv) Salivary Glands: Secrete saliva + Mucus (It is a sticky, gelatinous material that lines your lungs, throat, mouth, nose, and sinuses.) + Starch is converted into glucose by saliva (Salivary amylase)

(v) Oesophagus: Taking food from mouth to stomach by Peristaltic movements (Contraction and expansion of muscles of the oesophagus).

(vi) Stomach: Gastric glands present in stomach secrete gastric juice.

(vii) Small Intestine: The small intestine is the site of the complete digestion of carbohydrates, proteins and fats.

(a) Walls of small intestine secrete intestinal enzyme which convert Carbohydrates into glucose, fats in fatty acid + glycerol and Proteins into amino acids.

(b) It has Villi (finger like projection) which help in the absorption of food into blood.

(c) It receives the secretions of the liver and pancreas.
→ The food is acidic which is made alkaline for the pancreatic enzymes to act. The pancreas secretes pancreatic juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.
→ Fats are present in the intestine in the form of large globules which makes it difficult for enzymes to act on them. Bile salts break them down into smaller globules which increases the efficiency of enzyme action.

(viii) Large Intestine:
(a) Absorb excess of water.
(b) The rest of the material is removed from the body via the anus.