$A$ detritus food chain begins with which organism?

In the following food chain,grass provides $4000 \ J$ of energy to the grasshopper. How much energy will be available to the snake and the frog? Grass $\rightarrow$ Grasshopper $\rightarrow$ Frog $\rightarrow$ Snake.

Food web increases the stability of an ecosystem. Justify.

List two man-made ecosystems.

Differentiate between biodegradable and non-biodegradable substances. Cite examples.

The depletion of the ozone layer is a cause of concern. Why?