Our Environment

Notes

1. Environment

The environment includes everything surrounding us that affects living organisms.

Components of Environment

A. Biotic Components (Living)

Plants

Animals

Human beings

Bacteria

Fungi

B. Abiotic Components (Non-living)

Air

Water

Soil

Temperature

Sunlight

2. Ecosystem

Definition

An ecosystem is a functional unit where living organisms interact with one another and with their physical environment.

Types of Ecosystem

Natural Ecosystem

Forest

Pond

Grassland

Ocean

Artificial Ecosystem

Aquarium

Crop field

Garden

3. Components of Ecosystem

Producers (Autotrophs)

Green plants

Prepare food by photosynthesis

First trophic level

Example:

Grass, trees, algae

Consumers (Heterotrophs)

Depend on others for food.

Primary Consumers

Eat plants

Examples:

Deer

Goat

Rabbit

Secondary Consumers

Eat herbivores

Examples:

Frog

Lizard

Tertiary Consumers

Top carnivores

Examples:

Lion

Eagle

Tiger

Decomposers

Organisms that break down dead plants and animals.

Examples

Bacteria

Fungi

Importance

Recycle nutrients

Clean environment

Increase soil fertility

4. Food Chain

Definition

A food chain is a sequence of organisms through which food and energy pass.

Example

Grass → Grasshopper → Frog → Snake → Eagle

Each step is called a Trophic Level.

5. Trophic Levels

Trophic Level Organism

First Producers

Second Herbivores

Third Carnivores

Fourth Top Carnivores

6. Flow of Energy

Energy always flows in one direction.

Sun → Producers → Herbivores → Carnivores

Important Points

Energy never returns to the Sun.

It decreases at every trophic level.

Only about 10% energy is transferred to the next level.

7. Ten Percent Law

Proposed by Raymond Lindeman.

Statement

Only 10% of energy available at one trophic level is transferred to the next trophic level.

Example

Level Energy

Plants 10,000 J

Goat 1,000 J

Lion 100 J

Tiger 10 J

Numerical Example

If producers have 20,000 J

Primary consumer = 2,000 J

Secondary consumer = 200 J

Tertiary consumer = 20 J

8. Food Web

When many food chains are interconnected, they form a Food Web.

Advantages

Maintains ecological balance

Prevents extinction

Provides alternative food sources

9. Biological Magnification…