Class 8 Science Chapter 12: How Nature Works in Harmony – NCERT Solutions

Exercise Solutions: Class 8 Science Chapter 12 – How Nature Works in Harmony

1. Answer the following questions in about 30 words.

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

Answer: Loss of forest cover and changes in rainfall reduce the availability of food and water in elephant habitats. As a result, elephants wander into human farms and villages in search of resources like food and water, leading to conflict.

2. 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?

Answer: As a tree, I absorb water and minerals from the soil, synthesize food using sunlight (photosynthesis), and provide shelter and food to animals like birds and insects. I interact with fungi, bacteria, and other trees, forming a network of interdependence.

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

Answer: Earth can thrive without humans, as nature maintains a balance through natural processes. However, humans cannot survive without the earth, as it provides all necessary resources for life, including air, water, food, and shelter.

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

Answer: If two bird species compete for the same fruit, they may adapt by changing their feeding time, location, or develop different preferences over time (resource partitioning) to reduce competition and survive.

5. Can human actions cause natural disasters?

Answer: Yes, human actions like deforestation, pollution, and unplanned construction can increase the risk or intensity of natural disasters such as floods, landslides, and climate change-induced events.

2. Answer the following questions in about 150 words.

1. What are biotic and abiotic components in a habitat? Give suitable examples from a pond and a forest.

Answer: Biotic components are living elements in a habitat, such as plants, animals, and microorganisms. Abiotic components are non-living elements like air, water, soil, and temperature. For example, in a pond, biotic components include fish, grass, trees, and birds, while abiotic components are water and soil. In a forest, biotic components are plants, trees, and birds, and abiotic components include soil and air. Both types of components interact with each other, sustaining life and maintaining balance in the ecosystem.

2. How do food chains and food webs help maintain harmony in nature?

Answer: Food chains show the flow of energy from producers to various consumers, while food webs depict the interconnectedness of these chains. They help maintain harmony by ensuring energy transfer and regulating the population of organisms. If one organism is removed or increases in number, it affects others linked in the chain or web. These interdependencies keep populations in check and recycle nutrients, preserving ecological balance.

3. Explain with an example how one change in a component of an ecosystem can affect other components.

Answer: If pollution kills many plants in a pond, less oxygen is produced, resulting in fewer fish. With reduced fish, the number of insect larvae increases. These larvae may invade nearby farms, causing crop damage. Therefore, the disappearance or addition of one component affects others, disrupting the balance and leading to further changes in the ecosystem.

4. Why are decomposers essential for the functioning of ecosystems?

Answer: Decomposers like fungi and bacteria break down dead plants and animals, converting complex organic substances into simpler nutrients that enrich the soil. This process releases nutrients for use by plants and ensures continuous recycling of matter in nature. Without decomposers, dead matter would accumulate, and ecosystems would be deprived of essential nutrients.

3. Match the following.

Item	Match
1. Producer	(C) Green Plant
2. Herbivore	(A) Deer
3. Carnivore	(E) Tiger
4. Decomposer	(B) Mushroom
5. Omnivore	(D) Mouse

4. Complete the following table (based on Table 12.4 in the NCERT book).

Name of the organism	Performs photosynthesis	Feeds on plants and plant products	Feeds on animals	Feeds on both plants and/or animals
Deer	No	Grass and leaves of plants	No	Only on plants
Horse	No	Grass, leaves, grains	No	Only on plants
Vulture	No	No	Dead animals	Only on animals
Bengal Fox	No	Fruits, seeds	Small animals	Plants and animals
Bird (Shikra)	No	No	Small birds and insects	Only on animals
Squirrel	No	Nuts, fruits, seeds	Eggs, insects	Plants and animals
Mouse	No	Grains, fruits	Insects	Plants and animals
Mushroom	No	No	Dead organic matter	Decomposer
Tree	Yes	Not applicable	No	Producer

5. Answer in brief.

1. Why is it important to protect ecosystems like the Sundarbans?

Answer: Ecosystems like the Sundarbans protect us from storms and floods, maintain biodiversity, and provide resources like oxygen, water, and food. They are essential for ecological balance and human survival.

2. State two ways by which human farming practices can affect the ecosystem negatively and positively.

Answer: Negatively: Overuse of pesticides and monoculture can harm soil and reduce biodiversity. Positively: Sustainable farming and organic manure conserve soil and promote biodiversity.

6. Activity-based Questions (Brief answers):

1. Give one example where fish indirectly affect flowering plant seed production in pond habitats.

Answer: Fish feed on dragonfly larvae, reducing dragonfly numbers. Since dragonflies pollinate flowering plants, fewer dragonflies result in lower seed production in plants around the pond.

2. Briefly explain how decomposers help “recycle” nature’s waste.

Answer: Decomposers break down dead plant and animal matter, releasing nutrients back into the soil, ensuring nothing is wasted and nutrients are reused by plants.

---

Mastering How Nature Works in Harmony – NCERT Class 8 Science Chapter 12 Solutions 2025-26

Understanding ecosystems, food chains, and interdependence is vital for scoring well in Class 8 Science. This chapter explains how living and non-living components connect, helping students build a solid foundation for higher studies and practical life.

From biotic and abiotic interactions to the importance of decomposers, every topic in this chapter is easily explained. Focusing on activities and examples helps you remember concepts, prepare strong notes, and boost retention for exams.

Practice NCERT exercises regularly and review key definitions and diagrams. This approach will help you answer application-based questions with confidence and improve your overall marks in Science tests and school assessments.