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 (Biomagnification) Definition

The increase in concentration of harmful chemicals at successive trophic levels is called biological magnification.

Examples

DDT Mercury Lead

Highest concentration occurs in top consumers.

Effects

Diseases Reproductive problems Death of organisms 10. Biodegradable Waste