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Ecology

Written by Dr. Hira Salman (Biology)

8 Class 12 Biology questions with answers and explanations.

Printable worksheet with answer key

All questions with answers
  1. Only about what percentage of energy passes to the next trophic level?

    • 1 50 percent
    • 2 100 percent
    • 3 10 percent
    • 4 90 percent
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    Correct answer: 10 percent

    About 10 percent is a standard estimate.

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  2. A relationship in which both organisms benefit is:

    • 1 Predation
    • 2 Competition
    • 3 Mutualism
    • 4 Parasitism
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    Correct answer: Mutualism

    Both partners gain.

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  3. Bacteria that convert atmospheric nitrogen into ammonia are called:

    • 1 Photosynthetic bacteria
    • 2 Pathogens
    • 3 Nitrogen fixing bacteria
    • 4 Decomposers
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    Correct answer: Nitrogen fixing bacteria

    Rhizobium in root nodules is an example.

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  4. A group of organisms of the same species in an area is a:

    • 1 Ecosystem
    • 2 Population
    • 3 Biome
    • 4 Community
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    Correct answer: Population

    A population is a group of the same species.

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  5. Ecological succession starting on bare rock is called:

    • 1 Migration
    • 2 Secondary succession
    • 3 Primary succession
    • 4 Climax
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    Correct answer: Primary succession

    Primary succession starts where no soil exists.

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  6. The nitrogen in the air is converted to nitrates by:

    • 1 Animals
    • 2 Plants
    • 3 Bacteria
    • 4 Fungi only
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    Correct answer: Bacteria

    Soil bacteria carry out nitrogen fixation and nitrification.

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  7. The ozone layer is found in the:

    • 1 Troposphere
    • 2 Stratosphere
    • 3 Thermosphere
    • 4 Mesosphere
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    Correct answer: Stratosphere

    Ozone is concentrated in the stratosphere.

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  8. A pyramid of numbers shows the:

    • 1 Soil layers
    • 2 Energy only
    • 3 Biomass only
    • 4 Number of organisms at each trophic level
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    Correct answer: Number of organisms at each trophic level

    It counts individuals.

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