Class 8 Science · Original EZT practice
How Nature Works in Harmony (Class 8 Chapter 12): summary and practice
Plants, animals, soil, water and microbes depend on one another. Chapter 12 shows how living things share a place, who eats whom, what happens to waste and why the balance matters. All questions are original EZT tutor practice following the chapter's own section order. Edition note: this page covers the new NCERT book Curiosity (Grade 8). Older Class 8 books numbered chapters differently - check your chapter title, not just the number.
8 original worked examples, 8 fresh self-check questions and 4 mixed questions, with explained answers. These are not copied textbook exercises, an official chapter index or a full answer key. No affiliation with NCERT is claimed.
Official sources for topic and edition context, checked 20 October 2026:
1. Living together: community and ecosystem
Organisms living in one area form a community. The community together with its non-living surroundings - soil, water, air and light - is an ecosystem. Different organisms share a habitat and differ in what they eat.
2. Interactions
Organisms interact in different ways: some compete for the same food, one may feed on another, and some help each other. These interactions link their survival.
3. Who eats whom: food chains
Producers such as plants make food using sunlight. Consumers eat plants or other animals. Decomposers break down dead matter and waste. A food chain shows the order of feeding, and several chains join into a food web.
4. Waste, change and balance
In nature, waste is recycled: decomposers turn dead matter into nutrients. A change in one population affects the others - fewer predators let prey multiply and eat more plants. A healthy ecosystem gives food, clean air and water, and many other benefits.
Choose, solve, check, then try a fresh question.
Before calculating, read the method prompt and name the condition that makes it useful. Write your own attempt. Open the steps only when you need them, and use the check to catch a wrong sign, unit or interpretation. Finish with the fresh question before reading its answer.
Sort living and non-living parts
Choose the method: Ask whether each part is an organism or part of the surroundings.
EZT practice question
A pond has fish, frogs, algae, water and mud. Name the living and the non-living parts.
Show the worked solution
- Fish, frogs and algae are organisms.
- Water and mud are surroundings.
Answer: Living: fish, frogs and algae. Non-living: water and mud.
Check: Every part is either an organism or part of the physical setting.
Watch for this: Do not call algae non-living; they are organisms that make food.
Now try it yourself
Name two non-living parts of a forest ecosystem.
Check your answer
Soil and water (air and light also count).
They are surroundings, not organisms.
Define an ecosystem
Choose the method: Combine the community with its non-living surroundings.
EZT practice question
What is an ecosystem?
Show the worked solution
- Organisms in one area form a community.
- The community plus its non-living surroundings is the ecosystem.
Answer: A community of living things together with its non-living surroundings.
Check: The definition needs both the living and the non-living parts.
Watch for this: Do not stop at the community; an ecosystem also includes soil, water, air and light.
Now try it yourself
Define a community.
Check your answer
All the organisms living together in one area.
A community is the living part only.
Identify competition
Choose the method: Check whether two organisms need the same limited resource.
EZT practice question
Two bird species eat the same seeds in one field. What interaction is this?
Show the worked solution
- Both species need the same seeds.
- The seeds are limited.
Answer: Competition for food.
Check: Sharing one limited resource is the sign of competition.
Watch for this: Do not call it feeding on each other; both eat the seeds, not each other.
Now try it yourself
Give another example of competition.
Check your answer
Two saplings growing close together compete for sunlight.
Both need the same limited light.
Explain why interactions matter
Choose the method: Trace what each organism gets from the others.
EZT practice question
Why are interactions between organisms important?
Show the worked solution
- Interactions decide who gets food and space.
- They keep population numbers balanced.
Answer: They decide who gets food and space and keep numbers balanced.
Check: Removing an interaction changes the populations it links.
Watch for this: Do not treat each species as independent; survival is linked.
Now try it yourself
Why can most species not live entirely alone?
Check your answer
They depend on others for food and other needs.
Feeding and shelter links tie species together.
Name the producer and top consumer in a chain
Choose the method: The chain starts with a plant and ends with the animal nothing eats.
EZT practice question
In the chain grass, grasshopper, frog, snake, name the producer and the top consumer.
Show the worked solution
- Grass makes food from sunlight, so it is the producer.
- The snake is the last feeder, so it is the top consumer.
Answer: Producer: grass. Top consumer: snake.
Check: Energy flows from the producer up the chain to the top consumer.
Watch for this: Do not name the grasshopper as producer; it eats the grass.
Now try it yourself
Write one food chain with four links.
Check your answer
Grass, grasshopper, frog, eagle (any plant-to-animal order works).
A chain runs from a producer through consumers.
Explain the role of decomposers
Choose the method: Follow what happens to dead matter and waste.
EZT practice question
Why are decomposers needed in an ecosystem?
Show the worked solution
- Dead plants, animals and waste keep piling up otherwise.
- Decomposers break them down and return nutrients to the soil.
Answer: They break down dead matter and waste, returning nutrients to the soil.
Check: Producers then reuse those nutrients to grow.
Watch for this: Do not think waste simply disappears; something must break it down.
Now try it yourself
What happens to dead leaves on a forest floor?
Check your answer
Decomposers break them down into nutrients.
That is how nature recycles waste.
Predict how a change passes along a chain
Choose the method: Follow the feeding links upward and downward from the change.
EZT practice question
Many snakes are removed from a field. What may happen to frogs and grass?
Show the worked solution
- With fewer snakes, frogs face less predation and may increase.
- More frogs eat more insects, and the change passes down the chain.
Answer: Frogs may increase and eat more insects; the effects ripple along the chain.
Check: Each link responds to the one above and below it.
Watch for this: Do not expect only the snakes' prey to change; every linked population can shift.
Now try it yourself
Why does removing one species affect the others?
Check your answer
Feeding links connect them, so the change passes along the chain.
An ecosystem is a web of interactions, not separate species.
Name benefits of a healthy ecosystem
Choose the method: List what people and farms get from nature's balance.
EZT practice question
Name two benefits of a healthy ecosystem.
Show the worked solution
- Think of air, water, food and soil.
- Any two correct benefits answer the question.
Answer: Clean air and clean water (food and soil fertility also count).
Check: Healthy ecosystems support farms and daily life.
Watch for this: Do not list only products; services like clean air count too.
Now try it yourself
Name one benefit of an ecosystem to a farm.
Check your answer
Fertile soil (pollination or pest control also count).
Natural cycles keep the soil productive.
Try a mixed set
Choose a method or explanation before opening each answer.
1. What is an ecosystem?
Show answer and reason
Living things plus the non-living surroundings they interact with.
Both parts are needed for the definition.
2. What is a food chain?
Show answer and reason
The order in which living things feed on one another.
It traces who eats whom.
3. Who are decomposers?
Show answer and reason
Organisms that break down dead matter and waste.
They return nutrients to the soil.
4. Why does removing one species affect others?
Show answer and reason
Feeding links connect them, so the change passes along the chain.
Interactions link survival.
Try it yourself
Work these on paper before checking any notes. Answers are deliberately not shown here.
- Name the living and non-living parts of a garden ecosystem.
- Write a food chain with four links and mark the producer.
- What may happen to insects and plants if frogs are removed from a pond?
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Questions about this practice page
- What is an ecosystem?
- Living things plus the non-living surroundings they interact with.
- What is a food chain?
- The order in which living things feed on one another.
- Who are decomposers?
- Organisms that break down dead matter and waste, returning nutrients to the soil.
- Why does removing one species affect others?
- Feeding links connect them; the change passes along the chain.
- Are these the NCERT exercise questions for How Nature Works in Harmony (Class 8)?
- No. EZT pages are original practice following the chapter's section order - use them to prepare for the textbook exercises, not as a substitute for your book.