Ecosystems

Ecosystems are functional units of nature; where living organisms interact themselves and with their physical environment.
Th.e energy from the sun is transmitted to each and every organism in this biosphere by various food chains - the delicate relationships. If any block occurs in this the entire life forms will perish. Cycling of matter is also a process in ecosystem.
Nutrient cycles involve storage and transfer of nutrients through
the various components of the ecosystem so that the nutrients are repeatedly used Each regional biotic unit or biome characterised by its own flora and fauna. This chapter deals with the 'structure, functioning and examples of ecosystems.


1. The term ecosystem was coined by:
(a) Sir Arthur Tansley (b) E.P. Odum
(c) Writer (d) W.H. Pearsall
2. Green plants are:
(a) autotrophs (b) heterotrophs •
(c) saprophytes (d) parasites
3. A consumer that derives nutrition by eating plants is called:
(a) decomposer (b) saprophyte
(c) herbivore (d) carnivore
4. Which one of the following is a decomposer? (a) Algae (b) Fungi (c) Vulture_ (d) Frog
5. The energy flow in an ecOsystem is
(a) bidirectional (b) unidirectional
(c) multidirectional (d) both a and b
6. Which is a free living nitrogen-fixing bacterium?
(a) Azotobacter (b) Nitrosomonas
(c) Pseudomonas (d) Rhizobium
7. Grass -3 Insect Frog Snake Hawk. In this
food chain, the secondary consumer is (a) insect (b) snake (c) frog (d) grass
8. The grasslands in Russia are known as
(a) Prairies (b) Pampas
(c) Savannah (d) Steppe
9. Which orie of the following is an abiotic component of the ecosystem?
(a) Bacteria (b) Plants (c) Humus (d) Fungi
10. The biome of the Gir forests consists of the maximum number of which animal:
(a) Lion (b) Rhinoceros
(c) Hippopotamus (d) Crocodile
11. Sun's energy used by green plants for pho¬tosynthesis is:
(a) 1 m5% (b) 560/0 (c) 80- 90% (d) 100%
12. The plants which require very low tempera ture are called:
(a) rflegatherms (b) isotherms
mesotherms (d) microtherms
13. Temperate forests characterised by tall trees and shrubs with broad leaves are called: (a) chaparrals (b) taiga
(c) an forests (d) deciduous forests
14 The most abundant gas in the atmosphere is:
(a) oxygen (b) carbon dioxide
(c) nitrogen (d) hydrogen
15. The percentage of CO2 in the atmosphere is:
(a) 0.003% (b) 30% (c) 0.03% (d) 3%
16. Detritus food chainstarts with:
(a) phytoplanktons (b) dead organic matter
(c) green plants (d) macrophytes
17. The father of 'ecosystem ecology' is:
(a) E.P. Odum (b) A. Tansley
(c) Elton (d) H.T. Odum
18. The physical part of a biosphere is formed by.
(a) hydrosphere (b) lithosphere
(c) atmosphere (d) a, b, and c
19. Western Ghats is an example of:
(a) tropical deciduous forest
(b) temperate broad-leaved forest
(c) tropical rain forest
(d) temperate coniferous forest
20. The rate of convection of light energy into chemical energy of organic molecules in an ecosystem is:
(a) net primary productivity
(b) gross secondary productivity
(c) gross primary productivity •
(0) net secondary productivity
21. Which one of the following is the sedimentary type cf nutrient cycle?
(a) Nitrogen (b) Phosphorus (c) Carbon (d) Oxygen
22. The most common tree species in Indian tropical rain forests is
(a) Sal and Teak (b) Dipterocarpus and Hopea
(c) Acacia (d) Pine and Deodar
23. The anaerobic free - living nitrogen-fixing bacteria in soil is.
(a) Azotobacter (b) Clostridium
(c) Azospirillum (d) Rhizobium
24. The nitrogen -Axing actinomycete found in the root surface of Casuarina is:
(a) Frankia
(c) Pseudomonas
(b) Azospirillum
(d) Streptococcus
25. The pyramid of biomass is generally inverted in (a) aquatic ecosystem (b) grassland ecosystem
(c) terrestrial ecosystem (d) forest ecosystem
26. Which one of the following processes helps in nutrient conservation?
(a) Leaching (b) Nitrification
(c) Mineralisation (d) Immobilization
27 What fraction of assimilated energy is used in respiration by the herbivore?
(a) 40% (b) 60%
(c) 20% (d) 30%
28. Stratification is more common in
(a) dedduous forests (b) tropical rain forests
(c) temperate forests (d) tropical Savannas
29. In a food chain the maximum population is that of
(a) primary consumers (b) producers
(c) secondary consumers (d) tertiary consumers
30. A pyramid of numbers deals with the number of
(a) species in an ecosystem
(b) sub species in a community
(c) ndividuals in a community
(d) individuals in a trophic level
Answer Key
1. (a) 2, (a) 3. (c) 4. (b) 5. (b) 6. (a)
7. (c) 8. (d) 9. (c) 10. (a) 11. (a) 12. (d)
13. (d) 14. (c) 15. (c) 16. (b) 17 (a) 18. (d)
19. (c) 20. (c) 21. (b), 22. (b) 23. (b) 24. (a)
25. (a) 26. (c) 27. (d) 28. (b) 29. (b) 30. (d)