Decomposition involves the following processes :
1. Fragmentation - is the breaking down of the detritus into smaller particles . It increases the surface area of detritus for the action of microbes.
2. Leaching is the downward movement of water soluble inorganic nutrients into the soil horizon and their precipitation as unavailable salts.
3.Catabolism involves break down of detritus in the presence of extracellular enzymes released by the decomposers.
Usually the processes fragmentation , leaching and catabolism are carried out simultaneously on the detritus.
4.Humification involves transformation of simplified detritus into fully decomposed, dark coloured and amorphous humus. Humus acts as a reservoir of nutrients.
5. Mineralisation is the further breakdown of the humus by microbes to relase inorganic nutrients.
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?(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.
Discuss the role of healthy ecosystem services as a prerequisite for a wide range of economic, environmental and aesthetic goods and services.