Introduction

All living organisms perform certain essential activities to sustain life. These activities, such as nutrition (food intake, energy production), respiration (energy release, oxygen, ATP), transportation (blood circulation, nutrient flow), and excretion (waste management, removal of toxic substances), are collectively called life processes. They ensure that organisms grow, develop, and respond to their environment.

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1. What Are Life Processes?

Life processes are fundamental biological functions that organisms perform to maintain life. They include:
Nutrition (Obtaining and utilizing food for energy production)
Respiration (Releasing energy from food to produce ATP)
Transportation (Circulation of nutrients, oxygen, and waste)
Excretion (Eliminating urine, excess salts, and other waste products)

2. Nutrition – How Organisms Obtain Food

Types of Nutrition
Organisms obtain food in two ways:

(i) Autotrophic Nutrition (Plants and Some Bacteria)
Organisms self-feed by synthesizing their food using photosynthesis.
Example: Green plants, algae, and some bacteria.

Photosynthesis – The Process of Making Food
Photosynthesis occurs in green plants inside the chloroplasts, facilitated by chlorophyll.

Steps of Photosynthesis:

Absorption of sunlight by chlorophyll.
Splitting of water molecules, releasing oxygen.
Formation of glucose (food) for energy storage.

(ii) Heterotrophic Nutrition (Animals and Fungi)
Organisms depend on others for food (dependent on others).
Examples: Humans, animals, fungi.

Types of Heterotrophic Nutrition:

Holozoic Nutrition – Organisms consume solid food (e.g., humans, dogs).
Saprophytic Nutrition – Organisms feed on dead matter (e.g., fungi).
Parasitic Nutrition – Organisms rely on a host (e.g., tapeworms).

Nutrition in Humans – The Digestive System
The digestive system breaks down food using enzymes and includes:

Mouth – Begins digestion with saliva.
Esophagus – Moves food to the stomach.
Stomach – Releases enzymes and acids.
Small Intestine – Absorbs nutrients.
Large Intestine – Absorbs water.
Anus – Removes waste.

3. Respiration – Energy Production in Cells
Respiration is the process of breaking down glucose to release ATP (Adenosine Triphosphate).

Types of Respiration

(i) Aerobic Respiration (With Oxygen)

Glucose + Oxygen → Energy + Carbon Dioxide + Water
Occurs in most plants and animals.
Produces more energy.

(ii) Anaerobic Respiration (Without Oxygen)

Occurs in some microorganisms and muscle cells.
Produces less energy and leads to lactic acid buildup in animals.
In yeast fermentation, it produces ethanol and carbon dioxide.

Respiration in Humans – The Respiratory System

Nose – Filters air.
Trachea (Windpipe) – Passes air to the lungs.
Lungs – Absorb oxygen and expel carbon dioxide.
Diaphragm – Helps in breathing.

Gas Exchange in Lungs:
Oxygen absorption into blood.
Carbon dioxide expulsion from blood.

4. Transportation – Movement of Substances

Transportation in Humans – The Circulatory System
The circulatory system transports oxygen, nutrients, and waste throughout the body.

Main Components:

Heart – Pumps blood.
Blood – Carries oxygen, nutrients, and waste.
Blood Vessels – Transport blood.
Arteries – Carry oxygenated blood under high pressure.
Capillaries – Facilitate exchange of gases and nutrients.
Veins – Carry carbon dioxide-rich blood back to the heart.

Transportation in Plants – The Vascular System
Plants use xylem and phloem for transport:

Xylem – Carries water from roots to leaves (one-way movement).
Phloem – Carries food (glucose) to other parts.
Transpiration – Loss of water through stomata, aiding cooling.

5. Excretion – Removal of Waste
Excretion removes harmful waste substances.

Excretion in Humans – The Excretory System
Kidneys – Filter blood, remove waste via nephrons.
Ureters – Transport urine to the bladder.
Urinary Bladder – Stores urine.
Urethra – Expels urine from the body.

Excretion in Plants

Oxygen release – Byproduct of photosynthesis.
Resins and gums – Store waste substances for protective functions.

6. FAQs – Frequently Asked Questions

Q1: Why is nutrition important?
Nutrition provides energy for survival, growth, and metabolism.

Q2: What is the role of chlorophyll in photosynthesis?
Chlorophyll absorbs sunlight, aiding food production.

Q3: Why do we breathe faster during exercise?
More oxygen is needed for ATP production.

Q4: Why is the heart called a double pump?
It pumps oxygenated blood to the body and deoxygenated blood to the lungs.

Q5: Why do plants need both xylem and phloem?
Xylem transports water, while phloem distributes food.

Q6: How is oxygen transported in blood?
Hemoglobin carries oxygen to body cells.

Q7: What is ATP and why is it important?
ATP (Adenosine Triphosphate) is the cell’s energy carrier.

Q8: Why do kidneys filter blood?
To remove toxins and maintain body functions.

Q9: How do plants remove excess water?
Through transpiration via stomata.