Ecology and Ecosystem — GK Questions with Answers

1. In a grassland, what shape does the pyramid built from the count of organisms at each trophic level take?
   1. Inverted
   2. Upright
   3. Sometimes upright, sometimes inverted
   4. None of these
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   Answer: (B) Upright

   Grass plants are the most numerous and consumers decrease upward — so upright.

2. Which bacterium lives free in the soil and fixes atmospheric nitrogen?
   1. Nitrosomonas
   2. Pseudomonas
   3. Azotobacter
   4. Nitrobacter
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   Answer: (C) Azotobacter

   Nitrosomonas and Nitrobacter carry out nitrification; Pseudomonas denitrification.

3. The ecosystem that covers the largest area of the Earth is —
   1. Desert
   2. Grassland
   3. Mountain
   4. Marine
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   Answer: (D) Marine

   Oceans cover about 71% of the Earth's surface.

4. Choose the correct statements on biomagnification — 1. Poisons such as DDT enter the chain and accumulate at every trophic level. 2. Their amount is greater at higher trophic levels.
   1. 1 only
   2. 2 only
   3. Both 1 and 2
   4. Neither
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   Answer: (C) Both 1 and 2

   Fish-eating birds can carry DDT at concentrations millions of times that of the water.

5. How many links does a typical food chain usually have? (MPPCS 1996)
   1. Two
   2. Three
   3. Four
   4. Eight
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   Answer: (C) Four

   With ≈ 90% of energy lost at each link, chains rarely exceed 4–5 links.

6. The transition zone between two ecosystems is called — (IAS 2000)
   1. Biome
   2. Biotope
   3. Ecotone
   4. Sere
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   Answer: (C) Ecotone

   A sere is a series of successional stages; a biotope is a habitat unit.

7. Correct statements about ecosystems — 1. The term "ecosystem" was given by Tansley. 2. Organisms that make their own food are autotrophs. 3. Consumers obtain food by photosynthesis. 4. Decomposers convert inorganic matter into organic matter.
   1. 1 and 2
   2. 2 and 3
   3. 3 and 4
   4. All
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   Answer: (A) 1 and 2

   Producers photosynthesise; decomposers break organic matter into simple inorganic substances.

8. A species that is few in number yet has a decisive effect on its community is called —
   1. Endemic species
   2. Keystone species
   3. Cosmopolitan species
   4. Dominant species
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   Answer: (B) Keystone species

   Remove a keystone species and the structure of the community breaks down.

9. Statements — 1. Moving up a food chain, the number of species, total biomass and available energy decrease. 2. The more (or fewer) species an ecosystem has, the more complex (or simpler) its chains and webs.
   1. 1 only
   2. 2 only
   3. Both 1 and 2
   4. Neither
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   Answer: (C) Both 1 and 2

   The greater the diversity, the more complex the web.

10. Which term describes not only the space an organism occupies but also its functional role in the community? (IAS 2013)
    1. Ecotone
    2. Ecological niche
    3. Habitat
    4. Home range
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    Answer: (B) Ecological niche

    Niche = address + profession; the term was used by Grinnell (1917).

11. In food chains, which are decomposers? 1. Viruses 2. Fungi 3. Bacteria (IAS 2013)
    1. 1 only
    2. 2 and 3
    3. 1 and 3
    4. 1, 2 and 3
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    Answer: (B) 2 and 3

    Viruses multiply only inside living cells; they do not break down dead matter.

12. Which is the correct decreasing order of primary productivity per unit area? (IAS 2013)
    1. Oceans > lakes > grasslands > mangroves
    2. Mangroves > grasslands > lakes > oceans
    3. Mangroves > oceans > grasslands > lakes
    4. Grasslands > mangroves > lakes > oceans
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    Answer: (B) Mangroves > grasslands > lakes > oceans

    The open ocean, poor in nutrients, is the least productive.

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