Give reason/explain — Food web is important to maintain an ecosystem.

Give reason/explain — The existence of plant life is integral to the continuity and development of most ecosystems.

Draw the pyramid of numbers with a suitable example.

A river ecosystem is one where living organisms interact with each other and with the physical environment of flowing water. The Yamuna River in Delhi supports a variety of plants, fish, insects, birds and microorganisms. People also depend on it for water, recreation and cultural reasons. But over the years,pollution and encroachment have become major threats to this ecosystem.

To bring the river back to life, the Delhi government has launched a 'Yamuna Rejuvenation Plan'. Under this plan, the government has allocated large funds to build many small sewage treatment plants so that the waste water from homes is treated before reaching the river. The plan also includes reducing pollution by intercepting major drains and the government is even buying special dredging machines to clean up waste and silt in the river.

On the tourism side, there is a proposal to run eco-friendly cruises on the Yamuna. The boats would be solar- or battery-powered. Some people welcome this as a way to bring attention and care to the river. Others worry that tourism should only start after the river is fully cleaned.

(a) Name two abiotic and two biotic components of the Yamuna river ecosystem.

(b) Name two producers and two consumers in this river ecosystem.

(c) Write a simple food chain that is possible in this river ecosystem.

(d) As a student, what small actions can you take to prevent pollution and protect the Yamuna River?