(a) Taking an example of a small pond explain how the four components of an ecosystem function as a unit.
(b) Name the type of food chain that exists in a pond.
(a) The pond ecosystem is fairly a self-sustainable unit.
A pond is a shallow water body in which all the above mentioned four basic components of an ecosystem are well exhibited.
The abiotic component is the water with all the dissolved inorganic and
organic substances and the rich soil deposit at the bottom of the pond.
The solar input, the cycle of temperature, day-length and other climatic
conditions regulate the rate of function of the entire pond.
The autotrophic components include the phytoplankton, some algae and the floating,
submerged and marginal plants found at the edges.
The consumers are represented by the zooplankton, the free swimming and bottom dwelling forms.
The decomposers are the fungi, bacteria and flagellates especially
abundant in the bottom of the pond.
This system performs all the functions of any ecosystem and of the biosphere as a whole, i.e., conversion of inorganic into organic material with the help of the radiant energy of the sun by the autotrophs;
consumption of the autotrophs by heterotrophs;
decomposition and mineralisation of the dead matter to release them back
for reuse by the autotrophs.
(b) In the pond ecosystem the Grazing Food Chain is the major food chain for the energy flow. 
1. Plants are called as .......................because it fixes carbon dioxide.
2. In ecosystem, dominated by trees, the pyramid is.......................type.
3. In aquatic ecosystems, the limiting factor for the productivity is.......................
4. Common detritivores in our ecosystem are.......................
5. The major reservoir of carbon is.......................
Define ecological pyramids and describe with examples, pyramids of number and biomass.
Give an account of energy flow in an ecosystem.
(a) Grazing food chain and detritus food chain
(b) Production and decomposition
(c) Upright and inverted pyramid.
(d) Food chain and food web
(e) Litter and detritus
(f) Primary and secondary productivity.
Describe the advantages for keeping the ecosystems healthy.
Explain the carbon cycle with the help of a simplified model.
Explain how does:
(a) a primary succession start on a bare rock and reach a climax community?
(b) the algal bloom eventually choke the water body in an industrial area?(a) Explain primary productivity and the factors that influence it.
(b) Describe how do oxygen and chemical composition of detritus control decomposition?
It is often said that the pyramid of energy is always upright. On the other hand, the pyramid of biomass can be both upright and inverted. Explain with the help of examples and sketches.
(a) Explain the significance of ecological pyramids with the help of an example.
(b) Why are the pyramids referred to as upright or inverted?Discuss the role of healthy ecosystem services as a prerequisite for a wide range of economic, environmental and aesthetic goods and services.