What is meant by biogeochemical cycle? Name the two essentials which are transferred between different components of the biosphere.

Which of the following processes is not a step involved in the water cycle operating in nature?

Name the various organisms involved in the nitrogen cycle.

All living organisms are basically made up of $C, N, S, P, H$ and $O$. How do they enter the living forms? Discuss.

$(i)$ Name two biologically important compounds that contain both oxygen and nitrogen.
$(ii)$ What is the role of nitrogen-fixing bacteria?

Simran and Ria were enjoying dancing in the rain. Suddenly, a question struck Ria's mind: "How does rain fall on Earth?" To this, her elder sister Simran explained the water cycle: how clouds are formed when water evaporates due to the heating of water bodies, rises, expands, and cools to form tiny droplets that grow larger to form clouds, which then sprinkle rainwater onto the Earth. Simran also told Ria that this rainwater is essential and precious and must be conserved.
$(a)$ Which values are displayed by Simran?
$(b)$ Why is water conservation necessary?