Page 180 - Innovator's Science-8

3. Selvam from Cuddalore district, Tamil Nadu, shared that his milage was less affected by the 2004
Tsunami compared to nearby milages due to the presence of mangrove forests. This surprised Sarita,
Shabnam, and Shijo. They wondered if mangroves were protec ng the village. Can you help them
understand this?
Ans. Yes, Mangroves protect villages by ac ng like natural shields against storms and tsunamis. Their thick
forests slow down powerful winds and waves, while their strong roots hold the soil in place and prevent
it from washing away. The roots also absorb much of the force of water, reducing damage to coastal
areas. In places like the Sundarbans, a World Heritage Site, mangroves have shown how important they
are in protec ng communi es from natural disasters.
4. Look at this food chain:
Grass → Grasshopper → Frog → Snake
If frogs disappear from this ecosystem, what will happen to the popula on of grasshoppers and snakes?
Why?
Ans. • Grasshoppers: The popula on would likely increase because frogs, their main predators, are gone,
reducing preda on pressure.

• Snakes: The popula on would decrease because frogs are their primary food source, leading to food
scarcity.

• Why: In a food chain, the removal of a middle trophic level (frogs) disrupts the balance. Fewer
predators allow prey (grasshoppers) to mul ply, while the loss of prey affects higher predators
(snakes).

5. In a school garden, students no ced fewer bu erflies the previous season. What could be the possible
reasons? What steps can students take to have more bu erflies on campus?
Ans. • Possible reasons: Possible causes include pes cide use killing larvae, loss of nectar plants, or
increased predators (e.g., birds). Monoculture or pollu on might also reduce habitat quality.
• The steps we can take: Plant diverse nectar-rich flowers (e.g., marigolds), avoid pes cides, create
sheltered areas, and install bu erfly feeders or water sources to a ract and support bu erflies.
6. Why is it not possible to have an ecosystem with only producers and no consumers or decomposers?
Ans. An ecosystem depends on consumers and decomposers to stay balanced. Consumers, like herbivores
and carnivores, help control the number of producers by ea ng plants and other animals, keeping
popula ons in check. Decomposers, such as fungi and bacteria, break down dead plants and animals
into simple nutrients that go back into the soil for new plants to use. Without consumers, plants would
grow too much and compete for space and resources. Without decomposers, nutrients wouldn't return
to the soil, and the ecosystem would eventually collapse.

7. Observe two different places near your home or school (e.g., a park and a roadside). List the living and
nonliving components you see. How are the two ecosystems different?
Ans. Around our homes and schools, we can observe many things in places like parks and roadsides. In a park,
we find living things such as trees, birds, squirrels, and grass, along with non-living things like soil, water,
benches, and sunlight. By the roadside, living things like weeds and insects can be seen, while non-living
things include asphalt, dust, and car exhaust. The park is a planned and balanced ecosystem that
supports a variety of plants and animals, while the roadside is a disturbed area affected by human
ac vity, with fewer species and more pollu on.

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