Life Processes

Notes

1. Life Processes

Definition

The basic functions performed by living organisms to maintain life are called life processes.

Main Life Processes

Nutrition

Respiration

Transportation

Excretion

These processes help in growth, repair, reproduction, and survival.

2. Nutrition

Definition

Nutrition is the process by which organisms obtain food and use it for energy, growth, and repair.

Types of Nutrition

(A) Autotrophic Nutrition

Organisms prepare their own food by photosynthesis.

Requires:

Sunlight

Chlorophyll

Carbon dioxide

Water

Examples: Green plants, algae

Photosynthesis Equation

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

(In the presence of sunlight and chlorophyll)

(B) Heterotrophic Nutrition

Organisms obtain food from other organisms.

Types

Type Example

Holozoic Human beings, Amoeba

Saprophytic Mushroom, Bread mould

Parasitic Cuscuta, Tapeworm

3. Nutrition in Amoeba

Amoeba follows holozoic nutrition.

Steps

Ingestion – Food is engulfed using pseudopodia.

Digestion – Food is digested inside the food vacuole.

Absorption – Digested food enters the cytoplasm.

Assimilation – Food is used for energy and growth.

Egestion – Undigested food is removed.

4. Human Digestive System

Main Parts

Mouth

Oesophagus

Stomach

Small Intestine

Large Intestine

Rectum

Anus

(A) Mouth

Food is chewed by teeth.

Salivary glands secrete saliva.

Salivary amylase converts starch into sugar.

(B) Oesophagus

Food reaches the stomach by peristaltic movement.

(C) Stomach

The stomach secretes:

Hydrochloric Acid (HCl)

Pepsin

Mucus

Functions

HCl kills germs.

Pepsin digests proteins.

Mucus protects the stomach wall.

(D) Small Intestine

The small intestine is the main site of digestion and absorption.

Digestive Juices

Bile Juice (Liver)

Neutralizes acidic food.

Breaks large fat globules into small droplets (emulsification).

Pancreatic Juice

Digests carbohydrates, proteins, and fats.

Intestinal Juice

Completes digestion.

Villi

Finger-like projections present in the small intestine.

Increase surface area for absorption of digested food.

(E) Large Intestine

Absorbs water and minerals.

Forms faeces.

(F) Rectum and Anus

Rectum stores faeces.

Anus removes faeces from the body.

5. Digestive Glands

Gland Secretion Function

Salivary Glands Saliva (Amylase) Digests starch

Liver Bile…