IMPORTNT QUESTIONS FOR PRACTICE
CLASS XII BIOLOGY
CHAPTER 14(ECOSYSTEM)
1.
(1 Mark)
Decomposition is faster if deteritus is rich in nitrogen and water soluble substance like sugars. When is the decomposition process
slower?
2.
Define standing crop?
3.
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?
4.
Differentiate between Sere and Seral communities.
5.
Who are generally the pioneer species in a Xerarch succession and in a Hyararch succession?
6.
Which metabolic process causes a reduction in the Gross Primary Productivity?
7.
What percentage of photosynthetically active radiation is captured by plants?
8.
Name the pioners of primary succession in water.
9.
Under what conditions would a particular stage in the process of succession revert back to an earlier stage?
10. Name an omnivore which occurs in both grazing food chain and the decomposer food chain
11. What is the ultimate source of energy for the ecosystems?
(2, 3,5Marks)
12. In the North East region of India, during the process of jhum cultivation, forests are cleared by burning and left for regrowth after a
year of cultivation. How would you explain the regrowth of forest in ecological term?
13. Why are nutrient cycles in nature called biogeochemical cyles?
14. Organisms at a higher trophic level have less energy available. Comment.
15. Apart from plants and animals, microbes form a permanent biotic component in an ecosystem. While plants have been referred to
as autotrophs and animals as heterotrophs, what are microbes referred to as? How do the microbes fulfil their energy
requirements?
16. What are the three types of ecological pyramids. What information is conveyed by each pyramid with regard to structure, function
and energy in the ecosystem
17. . “The energy flow in the ecosystem follows the second law of thermodynamics.” Explain.
18. What is a biogeochemical cycle. What is the role of the reservoir in a biogeochemical cycle? Give an example of a sedimentary cycle
with reservoir located in earth’s crust.
19. Define decomposition and describe the processes and products of decomposition.
20. What is primary productivity? Give brief description of factors that affect primary productivity
21. What is meant by ecological succession? Describe the different stages in which succession occurs?
22. Distinguish between
(a) Grazing food chain and detritus food chain (GFC & DFC )
(b) Production and decomposition
(c) Upright and inverted pyramid
(d) Food chain and Food web
(e) Litter and detritus
(f) Primary and secondary productivity
By-K C MEENA PGT BIOLOGY
KV VIKASPURI II SHIFT