🌿 Class 8 Science
Chapter 12: How Nature Works in Harmony
Based on NCERT "Curiosity" (2024). Simple notes for easy learning. Not a textbook replacement.
🌍 Real-World Analogy: Think of your school cafeteria! The kitchen staff grow and cook food using sunlight and raw ingredients — just like producers (plants). Students eating the food are like consumers (animals that eat plants or other animals). The cleaning staff clear away leftovers and waste — just like decomposers (bacteria and fungi) that break down dead material and return nutrients to the soil so new plants can grow!
🌳 Topic 1: What is an Ecosystem
An ecosystem is a place in nature.
It has living things like plants.
It also has non-living things like water.
Living and non-living things work together.
A pond or forest is an ecosystem.
🔗 Topic 2: Food Chains
A food chain shows who eats whom.
It starts with a plant always.
A small animal eats the plant.
A big animal eats the small one.
Energy moves in one line.
🕸️ Topic 3: Food Webs
A food web is many food chains.
Animals can eat many different foods.
Food chains join to make a web.
A web shows all the eating links.
Nature has webs, not just chains.
🌱 Topic 4: Producers and Consumers
Producers make their own food.
All green plants are producers.
Consumers eat other living things.
A cow eats grass. Cow is consumer.
Without producers, no food exists.
🍄 Topic 5: Decomposers
Decomposers break down dead things.
Bacteria are very tiny decomposers.
Fungi like mushrooms are decomposers too.
They turn dead leaves into soil.
Decomposers keep nature clean.
⚖️ Topic 6: Balance in Nature
Nature has a balance of all life.
Too many deer can eat all plants.
If plants die, animals have no food.
Every living thing has a role.
We must not disturb this balance.
🐅 Topic 7: Conservation of Wildlife
Conservation means protecting animals and plants.
Many animals are in danger today.
Hunting and cutting trees harms them.
We must save forests for animals.
Laws help protect wild animals.
🦏 Topic 8: Endangered Species
Endangered means very few are left.
The tiger is an endangered animal.
The one-horned rhino is endangered too.
If we do nothing, they may die out.
We must act fast to save them.
🏞️ Topic 9: National Parks and Sanctuaries
A national park is a safe place.
Animals live freely in parks.
Jim Corbett is a famous park in India.
A sanctuary also protects wild animals.
No hunting is allowed in these places.
🌲 Topic 10: Deforestation and Reforestation
Deforestation means cutting down many trees.
It causes soil to wash away.
Animals lose their homes.
Reforestation means planting new trees.
Planting trees helps nature heal.
🎨 Section 2 — Visual Diagrams
Diagram 1: A Simple Food Chain — Sun to Grass to Deer to Tiger
Diagram 2: Producers Make Food, Consumers Eat Food
Diagram 3: The Decomposer Cycle — Dead Things Become Soil for New Plants
Diagram 4: Effects of Cutting Trees and Why We Must Plant More
Diagram 5: Famous National Parks and Sanctuaries in India
🧩 Section 3 — Solved Examples
🔗 Example 1: Making a Food Chain
Put these in a food chain: Tiger, Grass, Deer. Who eats whom?
1
Find who makes food. Grass makes food.
2
Who eats grass? Deer eats grass.
3
Who eats deer? Tiger eats deer.
4
Write it in order with arrows.
Answer: Grass → Deer → Tiger. Grass is the producer. Deer and Tiger are consumers.
🍄 Example 2: Role of Decomposers
A dead bird falls on the ground. After many days it is gone. What happened?
1
The dead bird is organic matter.
2
Bacteria and fungi start breaking it.
3
They turn the body into nutrients.
4
These nutrients go into the soil.
Answer: Decomposers (bacteria and fungi) broke down the dead bird and turned it into soil nutrients.
🌲 Example 3: Why Save Forests?
A village cut all trees near a river. Now the river floods every year. Why?
1
Tree roots hold the soil in place.
2
Without trees, soil washes into the river.
3
The river gets shallow and blocked.
4
Rain water has no space. It floods.
Answer: Cutting trees caused soil to wash into the river. This blocked the river and caused floods. Planting trees (reforestation) would fix this.
📖 Section 4 — Key Terms Table
Word
What It Means (Simple)
Example
Ecosystem
Living and non-living things together
A pond with fish, water, rocks
Food Chain
Who eats whom in a line
Grass → Deer → Tiger
Food Web
Many food chains joined together
Deer eats grass and leaves
Producer
Makes its own food from sunlight
Grass, trees, algae
Consumer
Eats other living things
Deer, tiger, eagle
Decomposer
Breaks down dead things
Bacteria, mushrooms, fungi
Endangered
Very few left in the world
Tiger, one-horned rhino
Conservation
Protecting animals and plants
Making national parks
National Park
A safe area for wild animals
Jim Corbett, Kaziranga
Sanctuary
A protected place for animals
Bharatpur Bird Sanctuary
Deforestation
Cutting down many trees
Clearing forest for farming
Reforestation
Planting new trees again
Van Mahotsav tree planting
✏️ Section 5 — Practice Worksheets
Part A: Fill in the Blanks
1. An __________ has living and non-living things.
2. Plants that make their own food are __________.
3. __________ break down dead animals and plants.
4. Cutting many trees is called __________.
5. A __________ is a safe place for animals.
Part B: True or False
1. A tiger is a producer. ( )
2. Decomposers break down dead things. ( )
3. Cutting trees helps animals. ( )
4. A food web has many food chains. ( )
5. National parks allow hunting. ( )
Part C: Short Answer
1. Name two decomposers.
2. What is a food chain? Give one example.
3. Why should we plant more trees?
Part D: Match the Columns
Column A
1. Grass
2. Tiger
3. Mushroom
4. Jim Corbett
5. Cutting trees
Column B
a. Decomposer
b. National Park
c. Consumer
d. Deforestation
e. Producer
Part E: Draw and Label
Draw a food chain with four living things. Use arrows to show energy flow.
✅ Detailed Solutions — Section 5 Practice
Part A — Fill in the Blanks (Answers)
1. An ecosystem has living and non-living things.
2. Plants that make their own food are producers.
3. Decomposers break down dead animals and plants.
4. Cutting many trees is called deforestation.
5. A national park / wildlife sanctuary is a safe place for animals.
Part B — True or False (Answers)
1. False. A tiger is a consumer (it eats other animals), not a producer.
2. True. Decomposers like bacteria and fungi break down dead things and return nutrients to the soil.
3. False. Cutting trees harms animals by destroying their habitat.
4. True. A food web is made of many food chains linked together.
5. False. National parks do not allow hunting — they protect wildlife.
Part C — Short Answer (Answers)
1. Two decomposers: Bacteria and Fungi (e.g. mushrooms).
2. A food chain shows how energy passes from one living thing to the next. Example: Grass → Grasshopper → Frog → Snake → Eagle. Each arrow means "is eaten by."
3. We should plant more trees because trees give us oxygen to breathe, their roots hold soil together to stop erosion, and they provide food and shelter for birds and animals.
Part D — Match the Columns (Answers)
1 → e (Grass = Producer)
2 → c (Tiger = Consumer)
3 → a (Mushroom = Decomposer)
4 → b (Jim Corbett = National Park)
5 → d (Cutting trees = Deforestation)
🔄 Section 6 — Flip & Learn Cards
What is an ecosystem?
A place where living and non-living things work together.
What is a food chain?
It shows who eats whom in a line. Example: Grass → Deer → Tiger.
What is a producer?
A living thing that makes its own food. All green plants are producers.
What do decomposers do?
They break down dead things into soil. Bacteria and fungi are decomposers.
What does endangered mean?
Very few of that animal are left. Tigers and rhinos are endangered.
What is a national park?
A safe area for wild animals. No hunting is allowed there.
What is deforestation?
Cutting down many trees. It harms animals and causes soil to wash away.
Why is reforestation important?
Planting new trees gives animals homes and keeps soil and air clean.
🧠 Section 7 — Mind Map
Mind Map: All Topics at a Glance — How Nature Works in Harmony