1. Pyramid of numbers deals with number of
(a) species in an area
(b) individuals in a community
(c) individuals in a trophic level
(d) subspecies in a community.
2. If we completely remove the decomposers from an ecosystem, its functioning will be adversely affected, because
(a) mineral movement will be blocked
(b) the rate of decomposition will be very high
(c) energy flow will be blocked
(d) herbivores will not receive solar energy.
3. The ecological pyramid given below represents
(a) pyramid of numbers in a grassland
(b) pyramid of biomass in a fallow land
(c) pyramid of biomass in a lake
(d) energy pyramid in a spring.
4. Match Column I with Column II and choose the correct answer from the codes given below.
(a) A-(iii), B-(ii), C-(i), D-(v)
(b) A-(iv), B-(v), C-(iii), D-(i)
(c) A-(ii), B-(iii), C-(i), D-(iv)
(d) A-(iii), B-(ii), C-(iv), D-(i)
5. In the given food web, an increase in the population of hawks will not result in
(a) decrease in the population of rabbits and snakes
(b) decrease in the population of producers
(c) decrease in the population of lizards
(d) increase in the population of grasshoppers.
6. Peacock eats a snake and snake eats frog and frog eats insect while insect eats green plant then position of peacock is (a) primary producer
(b) secondary consumer
(d) top consumer at the apex of food pyramid.
7. The stable community structure of an ecosystem is termed as
(a) dominant community
(c) domicile factor
(d) climax community.
8. An organism contains carbon molecules which have passed through three levels of ecosystem. The organism is a
(a) primary consumer (b) tertiary consumer
(c) predator (d) producer.
9. Which of the following representations show the pyramid of numbers in a forest ecosystem?
(a) D and B (b) A and B
(c) B and C (d) A and C
10. The biomass available for consumption by the herbivores and the decomposers is called
(a) net primary productivity
(b) secondary productivity
(c) standing crop
(d) gross primary productivity.
11. Which of the following statements regarding food chain is false?
(a) In an aquatic ecosystem, grazing food chain is the major conduit for energy flow.
(b) In terrestrial ecosystems, a large fraction of energy flows through detritus food chain.
(c) The detritus food chain begins with dead organic matter.
(d) Primary consumers belong to the first trophic level.
12. The flow of energy in the ecosystem is
(a) bidirectional (b) cyclic
(c) unidirectional (d) multidirectional.
13. Which of the following processes during decomposition is correctly described?
(a) Catabolism – Last step in the decomposition under fully anaerobic condition
(b) Leaching – Water soluble inorganic nutrients rise to the top layers of soil
(c) Fragmentation – Carried out by organisms such as earthworm
(d) Humification – Leads to the accumulation of a dark coloured substance humus which undergoes microbial action at a very fast rate
14. Match the following and select the correct option.
15. Lindeman for the first time gave energy transfer law, which states that
(a) only 20% of the energy is transferred to each trophic level
(b) only 10% of the energy is transferred to each trophic level
(c) only 30% of the energy is transferred to each trophic level
(d) only 50% of the energy is transferred to each trophic level.
True or False
16. Decomposers are also called reducers because of their small size.
17. Certain animals of dry areas, e.g., Kangaroo rat do not drink water at all rather they use water from metabolism of food to run their body machinery.
18. Standing state is the amount of living biomass present in an ecosystem.
19. The amount of organic matter stored by producers per unit time per unit area is called gross primary productivity.
20. Deep sea and arid lands are low productivity ecosystems.
21. Food webs increase adaptability and competitiveness of the organisms.
22. Pyramid of numbers in forest ecosystem may be inverted or spindle shaped.
23. Biomass and standing crop of organic matter increase with ecological succession.
24. In a hydrosere, sedge meadow stage is inhabited by amphibious plants like Typha and Scirpus.
25. Wet deposition is the input of nutrients in an ecosystem in dissolved state.
Match The columns
26. Match Column I with Column II.
27. Match Column I with Column II. (There can be more than one match for items in Column I)
passage Based Questions
28.(A) Complete the given passages with appropriate words or phrases. (a) Formation of a bare area without any form of life is called (i) . Successful establishment of species in this bare area is called (ii) . Competition affects the individuals of species in various ways called (iii) .
(b) (iv) is the biotic succession occurring on an unoccupied area, e.g., (v) . It is a (vi) process. (vii) is the succession of communities in previously inhabited areas which have been naturally or artificially disturbed, e.g., (viii) .
(B) Read the given passage and correct the errors, wherever present.
Energy flow in an ecosystem is always multidirectional. There is increase in the content and flow of energy with rise in trophic level. Minimum energy content is present in producers. The pyramid of energy is always inverted.
Assertion & reason
In each of the following questions, a statement of Assertion (A) is given and a corresponding statement of Reason (R) is given just below it. Of the statements, mark the correct answer as :
(a) if both A and R are true and R is the correct explanation of A
(b) if both A and R are true but R is not the correct explanation of A
(c) if A is true but R is false
(d) if both A and R are false.
29. Assertion : Primary productivity is maximum at the tropics and minimum at poles.
Reason : Sunlight availability is maximum at the tropics and gradually decreases towards pole.
30. Assertion : Nearly 90% of energy is lost when it moves from one trophic level to another.
Reason : A large part of energy is consumed at each trophic level in respiration, maintenance of body heat and other activities.
31. Assertion : Crustose lichens are the primary colonisers on a bare rock.
Reason : These lichens are resistant to desiccation and produce acids which corrode rock surface for minerals to support their growth.
32. Assertion : During an ecological succession, the number of species, and the community biomass increases. Reason : At climax community of an ecological succession, the gross production of a community is almost equal to the community respiration.
33. Assertion : The life cycles of organisms occurring in the developmental stages of a succession are short and simple.
Reason : The life cycles of organisms occurring in mature stages are long and complex.
34. Assertion : Food web is more real than food chain.
Reason : The consumers in a food web become polyphagous.
35. Assertion : When the number or biomass of individuals at producer level is minimum and increases progressively at each trophic level in a food chain, an inverted pyramid is formed.
Reason : An inverted pyramid of numbers and biomass is found in terrestrial and grassland ecosystem, respectively.
36. Assertion : The number of trophic levels in a food chain may be 7-10.
Reason : Food chains are sustained by consumers and decomposers.
37. Assertion : Herbivores are also called key industry animals because they convert plant matter into animal matter.
Reason : Herbivores always occupy third trophic level in a food chain.
38. Assertion : About 2-10% of PAR is captured in photosynthesis as gross primary productivity.
Reason : About 20% of gross primary productivity is consumed in respiration so net capture of energy is 1.6-8% of PAR.
Figure Based Questions
39. Refer the given cycle and answer the following questions
(a) In the given cycle, identify the processes ‘X’ and ‘Y’.
(b) How the processes X and Y contribute to the phosphorus cycling pool?
40. Study the given food web and answer the following questions.
(a) Given food web contains some missing organisms.
(1), (2), (3) and (4). Identify them.
(b) Identify the number of primary consumers and top
consumers in the given food web