Textbook Solutions: Keep the Curiosity Alive

Keep the Curiosity Alive (Page 207-208)

Q1. Diagram Analysis

Question: Refer to the diagram (concentric circles of Population -> Community -> Ecosystem) and select the wrong statement.

• (i) A community is larger than a population. (Correct)
• (ii) A community is smaller than an ecosystem. (Correct)
• (iii) An ecosystem is part of a community. (Incorrect)

Answer: (iii). Explanation: An ecosystem includes the community plus the abiotic factors. Therefore, the community is a part of the ecosystem, not the other way around.

Q2. Disappearance of Decomposers

Question: If all decomposers disappear from a forest, what would happen? Answer:

1. Waste Pile-up: Dead plants, leaves, and animal bodies would accumulate and not decay.
2. Nutrient Depletion: The nutrients locked inside dead bodies would never return to the soil.
3. Plant Death: Plants would eventually die due to a lack of nutrients (like nitrogen and phosphorus) in the soil.
4. Ecosystem Collapse: Without plants, herbivores and carnivores would also die.

Q3. Mangroves and Tsunami

Question: Why was Selvam’s village less affected by the Tsunami due to mangroves? Answer: Mangrove forests have dense, tangled root systems that grow above the soil. These roots act as a physical barrier.

1. Shock Absorbers: They break the force of giant waves (like tsunamis) and strong winds.
2. Soil Anchor: They hold the soil tightly, preventing the land from being washed away.

Q4. Food Chain Disruption

Chain: Grass $\rightarrow$ Grasshopper $\rightarrow$ Frog $\rightarrow$ Snake Question: If frogs disappear, what happens to grasshoppers and snakes? Answer:

1. Grasshoppers (Prey): Their population will increase rapidly because there is no predator (frog) to eat them. This might lead to overgrazing of the grass.
2. Snakes (Predator): Their population will decrease because they have lost their food source (frogs). They might starve or have to migrate.

Q5. Fewer Butterflies

Question: Why are there fewer butterflies in the school garden? Possible Reasons:

1. Lack of Flowers: Fewer nectar-producing plants.
2. Pesticides: Use of chemicals in the garden killing caterpillars.
3. Habitat Loss: Removal of specific host plants where butterflies lay eggs. Steps to take:

• Plant more flowering plants.
• Stop using chemical pesticides.
• Provide water sources (puddles for mud-puddling).

Q6. Producers Only?

Question: Why can’t an ecosystem exist with only producers? Answer: An ecosystem needs recycling.

1. If there are only producers, they will eventually die.
2. Without consumers (to keep population in check) and decomposers (to recycle dead matter), the dead plants would pile up.
3. The soil would run out of nutrients, and the producers would eventually die out.

Q7. Comparing Two Places

Example:

• Place A (Park): Trees, grass, birds, squirrels (Biotic) + Soil, benches, fountain (Abiotic). Managed by humans.
• Place B (Roadside): Weeds, stray dogs, ants (Biotic) + Tarmac, dust, exhaust fumes (Abiotic). Harsh environment. Difference: The park has higher biodiversity and better conditions for growth than the roadside.

Q8. Sustainable Fields

Comment: “Human-made ecosystems like agricultural fields are necessary, but they must be made sustainable.” Answer: Agricultural fields are monocultures (growing one crop). They are unstable compared to natural forests. To make them sustainable:

• Use organic fertilizers instead of chemicals.
• Practice crop rotation to save soil health.
• Plant trees around the farm (agroforestry) to support birds and insects that control pests.

Q9. Hare Population Drop

Chain: Grass $\rightarrow$ Hare $\rightarrow$ Fox/Eagle Question: If Hares die of disease… Answer:

1. Grass (Producer): Will increase (less grazing).
2. Fox/Eagle (Predators): Will decrease due to lack of food. They might start hunting other animals (like mice) more aggressively, affecting those populations too.