How Nature Works in Harmony
Keep the curiosity alive
1. 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 community.
Answer:- (iii) An ecosystem is part of a community.
2. 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.
Answer:- If all decomposers suddenly disappear from a forest ecosystem, several changes would occur. Dead plants, animals, and waste would not break down, leading to an accumulation of organic matter. This would reduce the availability of nutrients in the soil, as decomposers like fungi and bacteria recycle nutrients back into the ecosystem through decomposition. As a result, plants would struggle to grow, affecting herbivores that depend on them for food, and this would disrupt the entire food chain.
Decomposers are essential because they break down complex substances in dead matter into simpler ones, returning important nutrients to the soil. This process supports plant growth and maintains the balance of the ecosystem, ensuring that nothing is wasted and resources are reused.
3. 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?
Answer:- Mangrove forests likely protected Selvam’s village from the 2004 Tsunami by acting as a natural barrier. Their dense roots can reduce the force of waves and storm surges, absorbing water and protecting coastal areas from flooding and damage, which explains why the village was less affected compared to nearby ones.
Regarding decomposers, they are essential because they break down dead plants, animals, and waste into simpler substances, recycling nutrients back into the soil. This process supports plant growth, ensuring a balanced environment where all organisms can thrive.
4. 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?
Answer:- If frogs disappear from the food chain:
1. Grasshopper population will increase
→ Frogs eat grasshoppers. Without frogs, no one will control the grasshopper population, so their number will rise.
2. Snake population will decrease
→ Snakes eat frogs. If there are no frogs, snakes will not get enough food, and their population will go down.
This change will disturb the balance of the ecosystem, as shown in the food chain:
Grass → Grasshopper → Frog → Snake
5. 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?
Answer:-
Possible reasons for fewer butterflies:
- Fewer flowering plants, which means less nectar for butterflies.
- Use of pesticides that may harm butterflies or their larvae.
- Pollution or loss of natural plants and shelter in the garden.
- Changes in weather or climate affecting butterfly visits.
Steps students can take:
- Plant more colorful, nectar-rich flowers that attract butterflies.
- Avoid using harmful chemicals or pesticides in the garden.
- Create a butterfly-friendly space with shade, water, and native plants.
- Spread awareness among students about protecting butterfly habitats.
6. Why is it not possible to have an ecosystem with only producers and no consumers or decomposers?
Answer:- It is not possible to have an ecosystem with only producers and no consumers or decomposers because:
1. Producers (like plants) make food using sunlight, but they do not use all the food they make.
2. Consumers (like herbivores, carnivores, omnivores) are needed to eat these plants and keep their number in control.
3. Decomposers (like fungi and bacteria) are very important because they break down dead plants, animals, and waste. They return important nutrients to the soil.
4. Without decomposers, waste and dead matter would pile up, and plants would not get enough nutrients from the soil.
5. All three – producers, consumers, and decomposers – are connected in a cycle. Removing one will break the cycle and harm the entire ecosystem.
Thus, an ecosystem needs all three types of organisms to stay balanced and healthy.
7. 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?
Answer:-
Park Ecosystem
1. Living (Biotic) Components:
- Plants: Trees (e.g., banyan, mango), grass, flowers.
- Animals: Birds, squirrels, butterflies, bees, worms.
- Microorganisms: Bacteria, fungi in soil.
2. Non-Living (Abiotic) Components:
- Air: Provides oxygen.
- Water: From ponds, sprinklers, or rain.
- Soil: Fertile, supports plants.
- Sunlight: For photosynthesis.
- Temperature: Warm days, cooler nights.
Roadside Ecosystem
1. Living (Biotic) Components:
- Plants: Weeds, small grasses, occasional trees.
- Animals: Ants, flies, stray dogs, some birds.
- Microorganisms: Fewer bacteria or fungi.
2. Non-Living (Abiotic) Components:
- Air: Dusty or polluted from traffic.
- Water: Only rainwater or puddles.
- Soil: Compacted, less fertile.
- Sunlight: May be blocked by buildings.
- Temperature: Hotter due to asphalt.
How the Two Ecosystems Differ
1. Diversity: Parks have more varied plants and animals (trees, birds, insects) due to better care, while roadsides have fewer species (weeds, hardy insects) due to harsh conditions.
2. Conditions: Parks have richer soil, regular water, and cleaner air, supporting more life. Roadsides have poor soil, less water, and polluted air, limiting organisms.
3. Human Impact: Parks are designed for biodiversity and recreation, while roadsides are disturbed by traffic and pollution.
4. Interactions: Parks support complex interactions like pollination and decomposition. Roadsides have simpler interactions due to fewer organisms.
8. ‘Human-made ecosystems like agricultural fields are necessary, but they must be made sustainable.’ Comment on the statement
Answer:- Human-made ecosystems like agricultural fields are necessary because they provide food and livelihood. However, they must be made sustainable to protect soil health, reduce pollution, and conserve biodiversity. Sustainable practices like organic farming, crop rotation, and reduced use of chemicals help maintain balance in the environment and ensure long-term food security.
9. If the Indian hare population (Fig. 12.20) drops because of a disease, how would it affect the number of other organisms?
Answer:- If the Indian hare population (Fig. 12.20) drops because of a disease, it would affect other organisms in the food web. The Indian hare is a herbivore that eats grass and is prey for carnivores like foxes, snakes, and eagles (Activity 12.6 and Fig. 12.11). A decrease in hares would lead to:
1. Effect on Predators: Foxes, snakes, and eagles would have less food, potentially reducing their populations due to starvation or forcing them to hunt other prey more intensely.
2. Effect on Grass: With fewer hares grazing, grass might increase temporarily, but this could disrupt the balance for other herbivores or lead to overgrowth.
3. Effect on Other Herbivores: Predators might target other herbivores like mice or grasshoppers more, possibly decreasing their numbers.
These changes show how a drop in the hare population can create a ripple effect, altering the balance of the ecosystem as organisms depend on each other through feeding relationships.
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