Students can keep Class 8 Science Extra Questions and Class 8th Curiosity Chapter 12 How Nature Works in Harmony Important Extra Question Answer handy for quick reference during exams.
Class 8 Science Chapter 12 How Nature Works in Harmony Extra Questions
Class 8 Science Chapter 12 Extra Questions on How Nature Works in Harmony
How Nature Works in Harmony Class 8 Very Short Question Answer
Question 1.
What is the top trophic level in a food chain?
Answer:
Top carnivores (e.g., eagle).
Question 2.
Name one producer in a forest ecosystem.
Answer:
Tree
Question 3.
What role do decomposers play in an ecosystem?
Answer:
They break down dead matter to recycle nutrients.
Question 4.
Give an example of a herbivore.
Answer:
Deer
Question 5.
What is the primary source of energy for producers?
Answer:
Sunlight
Question 6.
Name one ecosystem service provided by mangroves.
Answer:
Protection from tsunamis and storms.
Question 7.
What is a food chain?
Answer:
A linear sequence showing who eats whom in an ecosystem.
Question 8.
What caused the decline of frogs in India during the 1980s?
Answer:
Large-scale harvesting for frog leg exports.
Question 9.
Name one abiotic component of a pond.
Answer:
Water
How Nature Works in Harmony Class 8 Short Question Answer
Question 1.
Explain the difference between a community and an ecosystem.
Answer:
A community is all the populations of different species living and interacting in a habitat, while an ecosystem includes the community plus abiotic components like water and soil. For example, a pond community includes fish and plants, but an ecosystem adds water and sunlight.
Question 2.
How do fish indirectly affect seed production in plants near a pond?
Answer:
Fish eat dragonfly larvae, reducing adult dragonflies. Fewer dragonflies mean less predation on pollinators (bees, butterflies), increasing pollination and seed production.
Question 3.
What are the effects of the overuse of synthetic fertilizers on soil?
Answer:
Overuse hardens soil, reduces earthworm populations, decreases organic matter, and increases irrigation needs, leading to long-term fertility loss.
Question 4.
Describe one example of mutualism in nature.
Answer:
Honeybees and flowers exhibit mutualism, where bees pollinate flowers for reproduction, and flowers provide nectar for bees.
Question 5.
Why did the Government of India ban frog leg exports?
Answer:
The ban was imposed to protect frog populations, which control pests naturally. Their decline increased agricultural pests and pesticide use, harming the environment, so the ban aimed to restore ecological balance.
Question 6.
What is an ecological pyramid, and what does it show?
Answer:
An ecological pyramid is a graphical representation of the number, biomass, or energy at each trophic level. It shows that producers are most abundant at the base, while top carnivores are fewest at the top, reflecting energy loss.
Question 7.
How can students help increase butterfly populations in a school garden?
Answer:
Students can plant nectar-rich flowers, avoid pesticides, create sheltered areas, and provide water sources to attract and support butterflies.
How Nature Works in Harmony Class 8 Long Question Answer
Question 1.
Explain the structure and importance of a food web in an ecosystem with examples.
Answer:
A food web is a network of interconnected food chains showing multiple feeding relationships. It includes producers (e.g., grass), herbivores (e.g., grasshoppers, hares), carnivores (e.g., frogs, snakes), and top carnivores (e.g., eagles), with decomposers (e.g., mushrooms) recycling nutrients. For example, grass → grasshopper → frog → snake → eagle overlaps with grass → hare → fox, where snakes might eat hares. Its importance lies in providing resilience; if one species declines (e.g., frogs), others (e.g., snakes) can adapt by finding alternative prey, maintaining energy flow, and ecosystem stability.
Question 2.
Discuss the ecological consequences of the Green Revolution in India and suggest sustainable alternatives.
Answer:
The Green Revolution introduced synthetic fertilisers and pesticides, boosting food production but causing soil degradation, pest resistance, and reduced biodiversity. Overuse of hardened soil killed beneficial organisms (e.g., earthworms) and increased irrigation needs. Sustainable alternatives include organic farming with compost or Kunapajala, crop rotation, and diversity to reduce pests naturally, promoting long-term soil health and ecosystem balance.
Question 3.
Describe how human activities can disrupt ecosystem balance, using the example of frog harvesting in the 1980s.
Answer:
Human activities like over-harvesting disrupt ecosystems by removing key species. In the 1980s, exporting frog legs reduced frog populations, natural pest controllers. This led to more agricultural pests, increased pesticide use, soil and water pollution, and health risks. The imbalance shows how removing a middle trophic level affects prey (pests increase) and predators (e.g., snakes decline), necessitating the export ban to restore balance.
Question 4.
Explain the role of mangroves in protecting coastal ecosystems, with reference to the 2004 Tsunami.
Answer:
Mangroves protect coastal ecosystems by acting as natural barriers, slowing winds and waves during storms and tsunamis. Their roots stabilise soil, reducing erosion, and absorbing water impact. During the 2004 Tsunami, Cuddalore village in Tamil Nadu, with mangrove forests, was less affected than nearby areas, demonstrating their protective role. The Sundarbans’ mangroves further highlight this, safeguarding biodiversity and human settlements.
How Nature Works in Harmony Class 8 Case Based Questions
Question 1.
In a study of Pond A and Pond B, researchers found that Pond A with fish had more flowering plants, while Pond B without fish had fewer. Analyse why this difference occurred and suggest one human impact that could reverse it.
Answer:
The difference occurred because fish in Pond A eat dragonfly larvae, reducing adult dragonflies that prey on pollinators (bees, butterflies). More pollinators in Pond A increased plant pollination and seed production. In Pond B, without fish, more dragonflies reduced pollinators, lowering plant numbers. A human impact like overfishing could reverse this in Pond A by decreasing fish, allowing dragonflies to increase, reducing pollinators, and thus decreasing flowering plants.
Question 2.
Farmers in a village reported a decline in soil health after years of using synthetic fertilisers. They noticed fewer earthworms and harder soil. Suggest two sustainable practices they could adopt and explain their benefits.
Answer:
Two sustainable practices are using compost or Kunapajala and practicing crop rotation. Compost adds organic matter, enriching soil and supporting earthworms, which improve soil structure. Crop rotation diversifies plants, reducing pest buildup and maintaining nutrient levels, preventing soil hardening, and enhancing long-term fertility.
Question 3.
The Sundarbans mangrove ecosystem faces threats from illegal hunting and fuelwood collection. A conservation group proposes replanting mangroves and enforcing laws. Evaluate the effectiveness of these measures.
Answer:
Replanting mangroves would restore natural barriers, protecting against storms and erosion, and support biodiversity, as seen with the 2004 Tsunami protection. Enforcing laws would reduce illegal hunting and wood collection, preserving flora and fauna. Both measures are effective: replanting rebuilds the ecosystem, while law enforcement prevents further damage, ensuring long-term sustainability of this World Heritage Site.
How Nature Works in Harmony Extra Questions for Practice
Question 1.
Name one producer found in a pond ecosystem.
Question 2.
What is the role of vultures in a food chain?
Question 3.
Give an example of a carnivore.
Question 4.
What is an ecosystem service provided by decomposers?
Question 5.
Name one human activity that harms the Sundarbans ecosystem.
Question 6.
Explain the difference between a food chain and a food web.
Question 7.
How do mangroves protect coastal villages during natural disasters?
Question 8.
What are the effects of overfishing on a pond ecosystem?
Question 9.
Suggest two ways students can support butterfly populations in a garden.
Question 10.
Describe how the removal of a species from a food chain affects other organisms, using the example of frogs.
Question 11.
Discuss the impact of the Green Revolution on Indian agriculture and propose two sustainable farming practices.
Question 12.
Explain the importance of nutrient cycling in an ecosystem and the role of decomposers in this process.
MCQs
Question 1.
What is the main source of energy for producers in an ecosystem?
(a) Water
(b) Sunlight
(c) Soil
(d) Air
Question 2.
Which organism is classified as a decomposer?
(a) Deer
(b) Mushroom
(c) Eagle
(d) Grasshopper
Question 3.
What happens to pest populations when frog numbers decrease?
(a) They decrease
(b) They stay the same
(c) They increase
(d) They disappear
Question 4.
Which of the following is an example of an abiotic component?
(a) Fish
(b) Rocks
(c) Insects
(d) Plants
Question 5.
What was a major reason for the ban on frog leg exports in India?
(a) Lack of demand
(b) Ecological damage
(c) High production costs
(d) Disease outbreak
Fill in the Blanks
Question 1.
A group of the same species living in a habitat is called a ________________
Question 2.
________________ is the process by which plants make their own food using sunlight.
Question 3.
The relationship where both organisms benefit is known as ________________
Question 4.
________________ forests help protect coastal areas from storms and floods.
Question 5.
The Green Revolution introduced ________________ to boost agricultural yields.
State whether True or False
Question 1.
All ecosystems can survive without decomposers.
Question 2.
Mangroves have no role in reducing the impact of tsunamis.
Question 3.
Herbivores are found at the top of the food chain.
Question 4.
Overuse of pesticides can lead to the development of pest resistance.
Question 5.
A food web consists of a single feeding relationship.
Match the following
Question 1.
| Column A | Column B |
| 1. Grass | (a) Second |
| 2. Hare | (b) Third |
| 3. Snake | (c) First |
| 4. Eagle | (d) Fourth |
Question 2.
| Column A | Column B |
| 1. Mutualism | (a) Frog eating insects |
| 2. Parasitism | (b) Honeybees and flowers |
| 3. Predation | (c) Ticks on a dog |
| 4. Commensalism | (d) Orchids on tree branches |