Easy Notes
- All living organisms (biotic) and non-living things (abiotic) in an area = Ecosystem
- Examples: Forest, pond, aquarium
2. Components of Ecosystem
| Biotic | Abiotic |
|---|---|
| Plants, animals, humans, microbes | Soil, water, air, light |
3. Food Chain
- Sequence where one organism eats another and energy is transferred
Example:
Grass → Grasshopper → Frog → Snake → Hawk
4. Trophic Levels
- Each step in food chain = Trophic level
- Producers (plants)
- Primary consumers (herbivores)
- Secondary consumers (carnivores)
- Tertiary consumers (top carnivores)
5. 10% Law of Energy
- Only 10% of energy is transferred to next level
- 90% lost as heat
- Many interconnected food chains = Food Web
- More stable than single food chain
7. Decomposers
- Microbes like bacteria and fungi
- Break down dead plants & animals
- Recycle nutrients to soil
8. Waste Management
- Biodegradable waste: Can be decomposed (e.g. food, paper)
- Non-biodegradable waste: Cannot be decomposed (e.g. plastic, metals)
9. Ozone Layer
- Present in stratosphere
- Protects from harmful UV rays
- Damaged by CFCs (chlorofluorocarbons)
- Reuse
- Reduce
- Recycle
→ 3R Principle
MCQs
- Decomposers are:
a) Herbivores
b) Carnivores
c) Bacteria and fungi
d) Plants - Which is a producer?
a) Cow
b) Lion
c) Grass
d) Snake - Which waste is non-biodegradable?
a) Fruits
b) Plastic
c) Leaves
d) Cotton - 10% energy law was given by:
a) Newton
b) Darwin
c) Lindeman
d) Einstein - Which level has most energy?
a) Producers
b) Tertiary consumers
c) Secondary consumers
d) Decomposers - Ozone layer absorbs:
a) X-rays
b) UV rays
c) Infrared rays
d) Visible light - Food web gives:
a) Instability
b) Confusion
c) Stability
d) Fewer choices - Which is a biodegradable item?
a) Glass
b) Metal
c) Wood
d) Plastic - CFCs are used in:
a) Refrigerators
b) Solar heaters
c) Electric fans
d) Cooking gas - Main source of energy in ecosystem:
a) Moon
b) Fire
c) Wind
d) Sun - What will happen if decomposers are removed?
a) Soil will be rich
b) No harm
c) Waste will accumulate
d) Ozone hole increases - Snake is a:
a) Producer
b) Herbivore
c) Secondary consumer
d) Decomposer - Which of these is herbivore?
a) Frog
b) Goat
c) Snake
d) Hawk - UV rays cause:
a) Cold
b) Sunburn
c) Headache
d) None - Ecosystem without plants is:
a) Stable
b) Perfect
c) Impossible
d) Balanced
Assertion & Reason
A: Energy decreases as we go higher in food chain.
R: Only 10% energy is passed to next level.
a) Both true, R explains A
b) Both true, R doesn’t explain A
c) A true, R false
d) A false, R true
A: Plastic is biodegradable.
R: It decomposes quickly.
a) A true, R true
b) A false, R false
c) A true, R false
d) A false, R true
A: Plants are primary producers.
R: They consume herbivores.
a) Both true
b) A true, R false
c) A false, R true
d) Both false
A: Ozone protects Earth.
R: It reflects UV rays.
a) A true, R true, R explains A
b) A true, R false
c) A false, R true
d) Both false
A: CFCs are harmful to environment.
R: They cause ozone depletion.
a) Both true, R explains A
b) Both true, R doesn’t explain A
c) A true, R false
d) A false, R true
Case-Based Study
Passage:
A student noticed that garbage dumped in open area near her home was mostly plastic, food waste, and paper. She separated biodegradable from non-biodegradable waste and disposed properly.
- Plastic is:
a) Biodegradable
b) Organic
c) Non-biodegradable
d) Edible - Food waste is:
a) Harmful
b) Non-biodegradable
c) Biodegradable
d) Plastic - Separating waste is called:
a) Cleaning
b) Waste disposal
c) Segregation
d) Burning - Which waste should be recycled?
a) Banana peel
b) Leaf
c) Plastic bottle
d) Bread - What should be done with biodegradable waste?
a) Composting
b) Dumping in river
c) Burning
d) Storing
Reason-Based Questions
- Why are decomposers important?
They break down waste and recycle nutrients. - Why is plastic harmful?
It doesn’t decompose and pollutes land/water. - Why should we not burn waste?
It causes air pollution and health problems. - Why are plants called producers?
They make their own food using sunlight. - Why is 10% law important?
It explains energy loss at each trophic level. - Why is food web better than food chain?
It shows real connections and adds stability. - Why should we save ozone layer?
It protects us from harmful UV rays. - Why are non-biodegradable wastes a problem?
They stay in environment for years. - Why do we need sunlight in ecosystem?
It is the main source of energy. - Why do tertiary consumers get least energy?
Due to energy loss at each level. - Why are CFCs banned?
They cause ozone depletion. - Why is UV radiation harmful?
It causes skin cancer and other diseases. - Why should we segregate waste?
To dispose it properly and recycle easily. - Why are frogs both predator and prey?
They eat insects and are eaten by snakes. - Why is ecosystem incomplete without decomposers?
Waste will pile up and nutrients won’t recycle.
Final Answer Key
MCQs:
1–c, 2–c, 3–b, 4–c, 5–a, 6–b, 7–c, 8–c, 9–a, 10–d, 11–c, 12–c, 13–b, 14–b, 15–c
Assertion & Reason:
16–a, 17–b, 18–b, 19–b, 20–a
Case-Based:
21–c, 22–c, 23–c, 24–c, 25–a
