---
title: "NCERT Solutions Class 8 Science Ch 12 How Nature Works in Harmony"
url: https://www.swavid.com/science/class/8/chapter/how-nature-works-in-harmony/ncert-solutions
dateModified: 2026-10-07T16:16:51+00:00
---

# NCERT Solutions Class 8 Science Ch 12 How Nature Works in Harmony

This chapter's questions cover concepts related to ecosystems, habitats, biotic and abiotic components, food chains, food webs, ecological interactions, and environmental conservation.

Free PDF (7 pages): https://www.swavid.com/api/seo/pdf/ncert/science/class-8/swavid-ncert-solutions-class-8-science-chapter-12-how-nature-works-in-harmony-25963a010a.pdf

## Probe and ponder

### Question z

*3 marks · Short answer*

How might the loss of forest cover and changes in rainfall patterns lead to elephants to enter human farms and villages?

**Solution**

1. Loss of forest cover and changes in rainfall cause vegetation to become scarce and waterholes to dry up in natural habitats.
2. Deprived of food and water in their natural home, elephants wander into nearby human farms and plantations in search of food like bananas and sugarcane.
3. This leads to crop damage and conflict with human settlements.

**Answer:** Loss of forest cover and drying of waterholes force elephants to leave natural habitats in search of food and water, leading them to enter human farms and villages.

> Common mistake: Stating that elephants enter villages just for sport rather than scarcity of resources.

### Question z

*3 marks · Short answer*

Imagine you are a tree in a dense forest. What kind of relationships would you have with water, sunlight, other animals, and other components of the forest?

**Solution**

1. With sunlight, water, and carbon dioxide, a tree performs photosynthesis to produce its own food, acting as a producer.
2. With soil, roots absorb water and essential nutrients while holding the soil in place to prevent erosion.
3. With animals, the tree provides shelter, oxygen, and food such as fruits and leaves, while animals help in seed dispersal and pollination.

**Answer:** A tree interacts with abiotic components like sunlight, water, and soil for survival, and with biotic components like animals by providing food and shelter while receiving services like pollination and seed dispersal.

> Common mistake: Forgetting to mention the mutual dependence between the tree and animals or abiotic components.

### Question z

*3 marks · Short answer*

Do you think the Earth can thrive without humans? Can humans survive without the Earth?

**Solution**

1. The Earth can thrive without humans, as natural ecosystems and wildlife existed long before humans and maintain balance through natural interactions.
2. Humans cannot survive without the Earth, because we depend entirely on ecosystem benefits such as clean air, water, fertile soil, and food for survival.
3. Overuse and misuse of natural resources by humans only disturb the balance in nature, threatening human survival itself.

**Answer:** Yes, the Earth can thrive without humans, but humans cannot survive without the Earth because we entirely depend on its ecosystems for air, water, and food.

> Common mistake: Assuming humans can survive independently of Earth's natural resources.

### Question z

*3 marks · Short answer*

If two kinds of birds compete for the same fruit, how might their way of living change over time?

**Solution**

1. Competition for common resources like food helps control population size and keeps ecosystems balanced.
2. If two kinds of birds compete for the same fruit, it leads to resource scarcity and competition between them.
3. Over time, to reduce direct competition, the birds might adapt by changing their feeding times, feeding on different parts of the plant, or shifting to alternative food sources.

**Answer:** Competing for the same fruit leads to resource scarcity, causing birds to adapt over time by altering their feeding habits, timings, or food sources to reduce competition.

> Common mistake: Stating that one bird will instantly vanish without considering adaptation and competition.

### Question z

*3 marks · Short answer*

Can human actions cause natural disasters?

**Solution**

1. Yes, human activities can trigger or worsen disasters like floods and landslides.
2. Cutting down trees and destroying forests reduce soil binding and lead to severe soil erosion and landslides during heavy rains.
3. Unplanned urbanization and blocking natural water bodies can cause severe flooding.

**Answer:** Yes, human actions can trigger or worsen natural disasters such as floods and landslides through activities like deforestation and habitat destruction.

> Common mistake: Stating only 'Yes' without explaining how human actions like deforestation cause disasters.

## Keep the curiosity alive

### Question 1

*1 mark · MCQ*

Refer to the given diagram (Fig. 12.19) and select the wrong statement.

- A community is larger than a population.
- A community is smaller than an ecosystem.
- An ecosystem is part of a community.

**Solution**

1. According to Fig. 12.19, an ecosystem is larger than a community, as an ecosystem includes both the community and its abiotic environment.
2. Therefore, statement (iii) that an ecosystem is part of a community is wrong.

**Answer:** (iii) An ecosystem is part of a community.

> Common mistake: Confusing the hierarchical sizes of population, community, and ecosystem.

### Question 2

*3 marks · Short answer*

A population is part of a community. If all decomposers suddenly disappear from a forest ecosystem, what changes do you think would occur? Explain why decomposers are essential.

**Solution**

1. Decomposers like fungi and bacteria break down complex organic substances in dead plants and animals into simpler substances, returning important nutrients to the soil.
2. If all decomposers disappear, dead organic matter and waste would accumulate, and nutrients would not be recycled back into the soil.
3. This would cause plants to lack essential nutrients, ultimately disrupting the entire food chain and ecosystem balance.

**Answer:** Decomposers are essential because they break down dead matter, recycle nutrients back into the soil, and prevent the accumulation of waste.

> Common mistake: Forgetting that decomposers recycle nutrients for plants.

### Question 3

*3 marks · Short answer*

Selvam from Cuddalore district, Tamil Nadu, shared that his village was less affected by the 2004 Tsunami compared to nearby villages due to the presence of mangrove forests. This surprised Sarita, Shabnam, and Shijo. They wondered if mangroves were protecting the village. Can you help them understand this?

**Solution**

1. Mangrove forests grow in coastal regions where rivers meet the sea and are known for their dense root systems and dense trees.
2. During severe storms, waves, and tsunamis, mangrove forests act as a natural barrier that slows down strong winds and waves.
3. This absorption of wave energy reduces the destructive impact of water on coastal villages, protecting them from heavy damage.

**Answer:** Mangroves protected the village by slowing down strong winds and waves during the tsunami, acting as a natural protective barrier.

> Common mistake: Stating mangroves stop tsunamis completely instead of reducing their impact.

### Question 4

*3 marks · Short answer*

Look at this food chain:
Grass $\rightarrow$ Grasshopper $\rightarrow$ Frog $\rightarrow$ Snake
If frogs disappear from this ecosystem, what will happen to the population of grasshoppers and snakes? Why?

**Solution**

1. In the given food chain, grasshoppers eat grass, frogs eat grasshoppers, and snakes eat frogs.
2. If frogs disappear, the population of grasshoppers will increase because there are fewer predators to eat them.
3. On the other hand, the population of snakes will decrease due to a shortage of food since frogs are their primary prey.

**Answer:** Grasshopper population will increase due to fewer predators, while the snake population will decrease due to lack of food.

> Common mistake: Confusing the direction of population change for predators and prey.

### Question 5

*3 marks · Short answer*

In a school garden, students noticed fewer butterflies the previous season. What could be the possible reasons? What steps can students take to have more butterflies on campus?

**Solution**

1. Fewer butterflies might be noticed due to loss of habitat, lack of flowering plants for nectar, or the use of pesticides nearby.
2. Students can take steps such as planting a variety of flowering plants that provide nectar and acting as host plants for caterpillars.
3. Students can also avoid using chemical pesticides on campus and create a friendly habitat for pollinators.

**Answer:** Reasons include habitat loss and lack of flowers; students can help by planting flowering plants and avoiding pesticides.

> Common mistake: Failing to mention both the reasons and the corrective actions.

### Question 6

*3 marks · Short answer*

Why is it not possible to have an ecosystem with only producers and no consumers or decomposers?

**Solution**

1. Producers make their own food through photosynthesis, but they depend on consumers and decomposers to maintain ecological balance.
2. Without consumers, plant populations could grow unchecked, leading to intense competition and depletion of resources.
3. Without decomposers, dead matter would accumulate and nutrients would not be recycled back into the soil for producers to use.

**Answer:** An ecosystem requires consumers to control population sizes and decomposers to recycle nutrients, without which life cannot be sustained.

> Common mistake: Stating only that plants need animals for food, missing nutrient recycling and population control.

### Question 7

*3 marks · Short answer*

Observe two different places near your home or school (e.g., a park and a roadside). List the living and non-living components you see. How are the two ecosystems different?

**Solution**

1. A park has biotic components like grass, trees, and birds, and abiotic components like soil, water, and sunlight.
2. A roadside typically has fewer plants, scattered weeds, and abiotic components like paved roads, dust, and vehicles.
3. The two ecosystems differ in their biodiversity, available resources, and level of human interference.

**Answer:** A park has rich vegetation and diverse wildlife, whereas a roadside has sparse vegetation and high human activity.

> Common mistake: Listing only living beings and forgetting to mention non-living abiotic components.

### Question 8

*3 marks · Short answer*

'Human-made ecosystems like agricultural fields are necessary, but they must be made sustainable.' Comment on the statement

**Solution**

1. Agricultural fields are human-made ecosystems necessary to produce food for a large population.
2. Overuse of synthetic fertilisers, pesticides, and monoculture leads to soil degradation, loss of biodiversity, and environmental damage.
3. Making them sustainable involves using organic manure, crop rotation, and natural pest control methods to protect soil health and the environment.

**Answer:** Agricultural fields are needed for food security, but they must be managed sustainably using eco-friendly methods to prevent environmental damage.

> Common mistake: Saying that human-made ecosystems are completely unnecessary instead of focusing on the need for sustainability.

### Question 9

*3 marks · Short answer*

If the Indian hare population (Fig. 12.20) drops because of a disease, how would it affect the number of other organisms?

**Solution**

1. Hares are herbivores that feed on grasses and plants, and serve as prey for carnivores like foxes and eagles.
2. If the hare population drops due to disease, predators like foxes and eagles will face a shortage of food and their population may decline.
3. Conversely, grass and plant populations may temporarily increase due to reduced grazing by hares.

**Answer:** A drop in the hare population would decrease the number of predators like foxes and eagles due to lack of food, while plant populations may increase.

> Common mistake: Forgetting that interlinked food webs affect both higher trophic levels (predators) and lower trophic levels (producers).

## Frequently asked questions

### How many questions are there in the NCERT Class 8 Science Chapter 12 exercises?

This chapter contains a total of 14 questions across different sections for the 2026-27 session based on the new NCERT book. Specifically, there are 5 short answer questions under probe and ponder and 9 questions under keep the curiosity alive. You can find step-by-step solutions for all of them in SwaVid's free PDF on this page.

### Which topics do the exercise questions cover in this chapter?

The questions cover important concepts like biotic and abiotic interactions, competition and adaptation, habitat loss, animal-human conflict, and human dependence on ecosystems. Other topics include food web dynamics, sustainable agriculture, butterfly conservation, and the protective role of mangrove forests. SwaVid provides detailed answers to help you master all these themes.

### What is the hardest question type in Class 8 Science Chapter 12 and how should I approach it?

The multiple-choice and complex short answer questions involving food web changes and ecological levels can be challenging. To approach them, analyze the interdependencies between producers, consumers, and decomposers carefully before concluding. SwaVid's free PDF on this page breaks down these difficult concepts into simple steps.

### How do I write answers to score full marks in this chapter?

To secure full marks, structure your answers clearly by defining key ecological terms and providing relevant examples from your surroundings. Mention specific factors like human actions and natural disasters accurately when explaining ecosystem harmony. Referring to SwaVid's expert-verified solutions on this page will guide you on the exact presentation style required.

### Is the free PDF for Class 8 Science Chapter 12 available for download?

Yes, the complete and free PDF of NCERT solutions for this chapter is available right here on this SwaVid page. It is tailored for the new NCERT book under the NCF 2023 guidelines for the 2026-27 academic session. You can easily access it to support your daily revision and homework.

## Related pages

- [Class 8 Science chapters](https://www.swavid.com/science/class/8)

Solutions written by SwaVid, a personal AI tutor for Class 6 to 10 Maths and Science. Practise this chapter free: https://www.swavid.com/start/student