Our Environment
Introduction
The environment includes all living and non-living components surrounding an organism. These components interact with each other and help in the survival of life on Earth. The study of these interactions is called Ecology.
Ecosystem
An ecosystem is a functional unit of nature where living organisms interact with each other and with the physical environment.
Components of Ecosystem
- Biotic Components: Living organisms
- Producers
- Consumers
- Decomposers
- Abiotic Components: Non-living factors like air, water, soil, light, temperature
Producers
Producers are green plants that prepare their own food by the process of photosynthesis. They form the first trophic level in a food chain.
Consumers
Consumers depend on producers or other organisms for food.
- Primary consumers – Herbivores
- Secondary consumers – Carnivores
- Tertiary consumers – Top carnivores
Decomposers
Decomposers like bacteria and fungi break down dead plants and animals into simple substances and return nutrients to the soil.
Food Chain
A food chain shows the transfer of energy from one organism to another.
Food Web
A food web is a network of interconnected food chains. It provides stability to the ecosystem.
Trophic Levels
Each step in a food chain is called a trophic level.
- 1st Trophic Level – Producers
- 2nd Trophic Level – Primary Consumers
- 3rd Trophic Level – Secondary Consumers
- 4th Trophic Level – Tertiary Consumers
Energy Flow in Ecosystem
Energy flows unidirectionally from the Sun → Producers → Consumers. Energy is lost as heat at every trophic level.
Biological Magnification
The increase in concentration of harmful chemicals like pesticides at each trophic level is called biological magnification.
Ozone Layer
The ozone layer protects Earth from harmful ultraviolet (UV) radiation from the Sun.
Ozone Depletion
- Caused by CFCs (Chlorofluorocarbons)
- Leads to skin cancer, eye damage, and global warming
Waste Management
Proper waste management is essential to protect the environment.
Types of Waste
- Biodegradable Waste – Can be decomposed
- Non-biodegradable Waste – Cannot be decomposed
5R Principle
- Refuse
- Reduce
- Reuse
- Recycle
- Recover
MCQs: Our Environment
1. The living components of an ecosystem are called:
a) Abiotic
b) Biotic
c) Physical
d) Chemical
Answer: b) Biotic
2. Which of the following is an abiotic component?
a) Plants
b) Animals
c) Bacteria
d) Water
Answer: d) Water
3. Producers prepare their food by the process of:
a) Respiration
b) Digestion
c) Photosynthesis
d) Fermentation
Answer: c) Photosynthesis
4. Which organism occupies the first trophic level?
a) Herbivores
b) Carnivores
c) Producers
d) Decomposers
Answer: c) Producers
5. Which of the following is a primary consumer?
a) Lion
b) Deer
c) Eagle
d) Snake
Answer: b) Deer
6. A food chain shows:
a) Energy loss
b) Energy transfer
c) Food storage
d) Food competition
Answer: b) Energy transfer
7. Which of the following is a decomposer?
a) Grass
b) Tiger
c) Bacteria
d) Goat
Answer: c) Bacteria
8. A network of interconnected food chains is called:
a) Food pyramid
b) Trophic level
c) Food web
d) Ecosystem
Answer: c) Food web
9. The transfer of only 10% energy to the next trophic level is known as:
a) Energy cycle
b) 10% law
c) Food law
d) Energy pyramid
Answer: b) 10% law
10. Which trophic level has maximum energy?
a) Primary consumers
b) Secondary consumers
c) Tertiary consumers
d) Producers
Answer: d) Producers
11. Increase in concentration of toxic substances in a food chain is called:
a) Bioaccumulation
b) Biomagnification
c) Biodegradation
d) Bioremediation
Answer: b) Biomagnification
12. Which gas is mainly responsible for ozone layer depletion?
a) CO₂
b) SO₂
c) CFCs
d) O₂
Answer: c) CFCs
13. Ozone layer protects Earth from:
a) Infrared rays
b) Visible light
c) Ultraviolet rays
d) Gamma rays
Answer: c) Ultraviolet rays
14. Which waste can be decomposed by microorganisms?
a) Plastic
b) Glass
c) Biodegradable waste
d) Polythene
Answer: c) Biodegradable waste
15. Which of the following is non-biodegradable?
a) Vegetable waste
b) Paper
c) Plastic bag
d) Cow dung
Answer: c) Plastic bag
16. The 5R principle does NOT include:
a) Reduce
b) Refuse
c) Recycle
d) Replace
Answer: d) Replace
17. Which organism helps in nutrient recycling?
a) Producers
b) Herbivores
c) Decomposers
d) Carnivores
Answer: c) Decomposers
18. Which pyramid is always upright?
a) Pyramid of numbers
b) Pyramid of biomass
c) Pyramid of energy
d) Pyramid of food
Answer: c) Pyramid of energy
19. Which of the following is an example of secondary consumer?
a) Grass
b) Goat
c) Frog
d) Plants
Answer: c) Frog
20. Proper waste management helps in:
a) Pollution increase
b) Resource wastage
c) Environmental protection
d) Global warming
Answer: c) Environmental protection
0 Comments