Page 2 - Assignment-Ecosystem

plants can absorb it.
3. Atmospheric nitrogen dissolves readily in the soil but is washed out with every
rainfall.
4. Plants must absorb nitrogen through their roots, which are not in contact with
the atmosphere.
9. In general, the biomass in an ecosystem will be greatest at the trophic level
comprising ___________
1. secondary consumers
2. primary consumers
3. producers
4. tertiary consumers
10. Both hydrach and xerarch successions:
1. Take same time
2. Have similar sere
3. Lead to mesic conditions
4. Have same pioneer species
B. Very Short Answer Questions (1 mark each)

1. Decomposition is faster if deteritus is rich in nitrogen and water soluble
substance like sugars.When is the decomposition process slower?
2. If we count the number of insects on a tree and number of small birds depending
on those insects as also the number of larger birds eating the smaller, what kind
of pyramid of number would we get?
3. Differentiate between Sere and Seral communities.
4. Who are generally the pioneer species in a Xerarch succession and in a Hyararch
succession?
5. Which metabolic process causes a reduction in the Gross Primary Productivity?

C. Short Answer Questions-II (2 marks each)
6. What is the shape of pyramid of biomass in sea? Why?
7. Give an example of an ecological pyramid which is always upright. Justify your
answer.
8. Differentiate between primary succession and secondary succession. Which one
occurs faster?
9. Gaseous nutrient cycle and sedimentary nutrient cycles have their reservoir.
Name them. Why is a reservoir necessary?
10. Fill up the missing links depicted as A, B, C and D in the given model of primary
succession.