Probe and Ponder
- How might the loss of forest cover and changes in rainfall patterns lead to elephants entering human farms and villages?
When forests shrink due to cutting trees or less rain, elephants lose their food and water. They wander into farms for crops like bananas or sugarcane, causing damage. This happens because their natural habitat can’t support them anymore, leading to conflicts with humans. - 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?
As a tree, I’d soak up water from soil for growth, use sunlight to make food (photosynthesis), provide shade and fruits for animals like birds and monkeys, and my roots would hold soil to prevent erosion. Animals might help by spreading my seeds, and I’d release oxygen for everyone—it’s all connected! - Do you think the Earth can thrive without humans? Can humans survive without the Earth?
Yes, Earth can thrive without humans—nature balanced itself for millions of years before us with plants, animals, and weather cycles. But humans can’t survive without Earth; we need its air, water, food, and resources. We’re part of nature, not separate! - If two kinds of birds compete for the same fruit, how might their way of living change over time?
Over time, one bird might adapt by eating different fruits or at different times to avoid fights. The other could evolve stronger beaks or move to new areas. This competition helps balance populations and encourages changes for survival. - Can human actions cause natural disasters?
Yes, actions like deforestation can cause floods or landslides by removing trees that hold soil and absorb water. Pollution and climate change from burning fuels can lead to stronger storms or droughts. We’re not causing all disasters, but we can make them worse. - Share your questions
Here are some fun questions from the chapter: How do decomposers help recycle waste? Why are mangroves important for coastal areas? What happens if predators disappear from a forest? How can we make farming more eco-friendly?
Keep the Curiosity Alive
Refer to the given diagram (Fig. 12.19) and select the wrong statement.
(i) A community is larger than a population.
(ii) A community is smaller than an ecosystem.
(iii) An ecosystem is part of a community.
Ans: (iii) An ecosystem is part of a community.
Actually, a community (groups of populations) is part of an ecosystem, which includes both living things and non-living parts like soil and water. The other statements are correct: communities are larger than populations and smaller than ecosystems.- 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.
Ans: Dead plants and animals would pile up without breaking down, leading to less nutrients in the soil. Plants might not grow well, affecting herbivores and the whole food chain. Decomposers like fungi and bacteria are essential because they recycle nutrients back into the soil, keeping the ecosystem healthy and balanced. - 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?
Ans: Yes, mangroves act like natural barriers! Their roots slow down waves and winds during tsunamis or storms, reducing damage to villages. They also absorb carbon dioxide, prevent erosion, and provide homes for animals— that’s why Selvam’s village was safer. - Look at this food chain: Grass → Grasshopper → Frog → Snake. If frogs disappear from this ecosystem, what will happen to the population of grasshoppers and snakes? Why?
Ans: Grasshoppers would increase because fewer frogs eat them, leading to overeating of grass. Snakes would decrease because they lose their main food (frogs). This shows how removing one link disrupts the balance—frogs control grasshoppers and feed snakes. - 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?
Ans:
Reasons: Fewer flowers (food for butterflies), pesticide use killing them, or weather changes.
Steps: Plant nectar-rich flowers like marigolds, avoid chemicals, create shady spots, and add water sources. This attracts butterflies and helps pollination! - Why is it not possible to have an ecosystem with only producers and no consumers or decomposers?
Ans: Producers like plants make food, but without consumers (animals that eat them), plant populations would explode and use up resources. No decomposers means no nutrient recycling—dead stuff piles up, and soil gets poor. All parts are needed for balance! - 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?
Ans: Park: Living—trees, birds, insects, grass; Non-living—soil, water pond, sunlight, air. Roadside: Living—few weeds, ants, stray dogs; Non-living—asphalt, rocks, polluted air, vehicles. Differences: Park has more biodiversity and clean air; roadside is disturbed by traffic and has less life. - ‘Human-made ecosystems like agricultural fields are necessary, but they must be made sustainable.’ Comment on the statement.
Ans: Farms provide food, but overuse of chemicals harms soil and wildlife. Sustainable means using organic methods, crop rotation, and less water to keep soil healthy and reduce pollution. This way, farms last longer without damaging nature. 
If the Indian hare population (Fig. 12.20) drops because of a disease, how would it affect the number of other organisms?
Deer might increase (less competition for grass), but foxes and eagles would decrease (less food). Grass could grow more with fewer hares eating it. Overall, the food web shifts—predators suffer, plants thrive, showing hares are key for balance.
Discover, Design, and Debate
- Plan a clean-up day at school or a nearby park. Wearing gloves and using bags, collect the litter you find. Discuss the kinds of waste you found. Which was the most common? How can we reduce such waste?
Ans: Organize with friends—pick a Saturday, get gloves, bags, and posters saying “Keep Nature Clean!” Common waste: Plastic bottles, wrappers, paper. Plastics are most common because they’re not biodegradable. Reduce by using reusable bags, recycling, and teaching others—no littering! This helps ecosystems by preventing pollution that harms animals and plants. - In Arunachal Pradesh, the Nyishi and Mishmi tribes treat the Tiger as sacred. In Chhattisgarh, the Baiga tribe worships Bagheshwar or Bagesur Dev and believes the Tiger is the protector of the forest. Find out about another Indian tribe that has a special bond with any animal.
Ans: The Bishnoi tribe in Rajasthan has a special bond with blackbucks (antelopes). They protect them as sacred, following Guru Jambheshwar’s teachings to not harm animals or trees. This helps conserve wildlife—Bishnois even risk their lives to save them! It’s a great example of how culture protects ecosystems. - Pick a tree near your home or school. Observe it once a week for 4 weeks. Note any new leaves, flowers, fruits, or visiting birds and insects. Record your observations. You may even upload your findings to www.seasonwatch.in and become a young citizen scientist.
Ans: I picked a mango tree. Week 1: New green leaves budding, ants crawling. Week 2: Small flowers blooming, bees visiting. Week 3: Tiny fruits forming, birds like sparrows perching. Week 4: Fruits growing bigger, squirrels eating. Upload to SeasonWatch to track changes with seasons—it’s fun and helps scientists study climate effects on trees! - Interact with farmers and record indigenous practices followed by them for sustainable farming. Create a sustainable herbal garden/natural farm at home or at school. It could be a group activity with students from different grades.
Ans: Talked to a farmer who uses cow dung as natural fertilizer (compost) and plants marigolds to repel pests—instead of chemicals.
For our school garden: Plant herbs like tulsi and mint in pots with organic soil, water wisely, and rotate crops. Involve juniors to weed and seniors to label—it’s sustainable, provides fresh herbs, and teaches eco-farming! - Look at Fig. 12.21 to understand the different farming practices adopted by farmers or you may also visit a nearby farm with an elderly person to observe the same. List a few suggestions in your notebook to improve farming practices by adopting eco-friendly and sustainable techniques. You can also make posters or model and display while participating in school functions, science fairs or Krishi Mela. The school may also invite agricultural scientists, farmers, and experts to discuss the prevalent farming practices with the students.
Ans: From the figure/visit: Farmers use crop rotation, natural manure, and drip irrigation. Suggestions: Use compost instead of chemicals, plant diverse crops to boost soil health, harvest rainwater. Make posters like “Go Organic for Healthy Soil!” and a model farm with recycled materials. Invite experts for a talk—learn about Vrikshayurveda (ancient organic methods) and share in a school fair!