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 Juice Emulsifies fats Pancreas Pancreatic Juice Digests carbohydrates, proteins and fats 6. Respiration Definition