Chapter 12 Solutions — Ecosystem

Chapter-end Exercises

1. 1.
   Fill in the blanks.

   • (a) Plants are called as_________ because they fix carbon dioxide.
   • (b) In an ecosystem dominated by trees, the pyramid (of numbers) is_________ type.
   • (c) In aquatic ecosystems, the limiting factor for the productivity is_________.
   • (d) Common detritivores in our ecosystem are_________.
   • (e) The major reservoir of carbon on earth is_________.
2. 2.
   Which one of the following has the largest population in a food chain?

   • (a) Producers
   • (b) Primary consumers
   • (c) Secondary consumers
   • (d) Decomposers
3. 3.
   The second trophic level in a lake is

   • (a) Phytoplankton
   • (b) Zooplankton
   • (c) Benthos
   • (d) Fishes
4. 4.
   Secondary producers are

   • (a) Herbivores
   • (b) Producers
   • (c) Carnivores
   • (d) None of the above
5. 5.
   What is the percentage of photosynthetically active radiation (PAR) in the incident solar radiation?

   • (a) 100%
   • (b) 50%
   • (c) 1-5%
   • (d) 2-10%
6. 6.
   Distinguish between

   • (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
7. 7.
   Describe the components of an ecosystem.
8. 8.
   Define ecological pyramids and describe with examples, pyramids of number and biomass.
9. 9.
   What is primary productivity? Give brief description of factors that affect primary productivity.
10. 10.
    Define decomposition and describe the processes and products of decomposition.
11. 11.
    Give an account of energy flow in an ecosystem.