Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A):  Lichens are commonly the pioneer species during primary succession on rocks.
Reason (R):  Lichens are able to secrete acids to dissolve rocks.
 In the light of the above statements, choose the most appropriate answer from the options given below :
1.  Both (A) and (R) are true and (R) is the correct explanation of (A).
2.  Both (A) and (R) are true but (R) is not the correct explanation of (A).
3.  (A) is true but (R) is false.
4.  Both (A) and (R) are false.

  1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
  2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
  3. If the assertion is true but the reason is false
  4. If both the assertion and reason are false

Subtopic:  Ecological Succession (OLD NCERT) |
 85%
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Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A):  Low temperature and anaerobiosis inhibit decomposition resulting in build-up of organic chemicals. 
Reason (R):  Most decomposers are anaerobic psychrophiles.

In the light of the above statements, choose the most appropriate answer from the options given below:

1.  Both (A) and (R) are true and (R) is the correct explanation of (A).
2.  Both (A) and (R) are true but (R) is not the correct explanation of (A).
3.  (A) is true but (R) is false.
4.  Both (A) and (R) are false.

  1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
  2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
  3. If the assertion is true but the reason is false
  4. If both the assertion and reason are false
Subtopic:  Decomposition |
 55%

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Sometimes the term "detritivore" is used interchangeably with:

1.decomposers2.primary consumers
3.secondary consumers4.autotrophs

Subtopic:  Decomposition |
 90%
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The minimum requirement for an ecosystem to recycle nutrients present in it would be:

1.  producers
2.  producers and decomposers
3.  producers, primary consumers, and decomposers
4.  producers, primary consumers, secondary consumers, and decomposers
Subtopic:  Decomposition |
 52%

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Net primary productivity is the gross primary productivity minus:

1.  that which is consumed by herbivores
2.  that which is consumed by the producer in metabolism
3.  secondary productivity
4.  loss due to mortality
Subtopic:  Ecosystem Productivity |
 84%
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Most organic material is converted to carbon dioxide, which can then be utilized in primary production by:
1. autotrophs
2. secondary consumers
3. herbivores
4. carnivores

Subtopic:  Energy Flow |

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The best way to describe an ecosystem would be that they are:

1.  processors of energy and transformers of matter.
2.  processors of matter and transformers of energy.
3.  processors of matter and energy.
4.  transformers of matter but not of energy.

Subtopic:  Introduction |
 71%

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The amount of carbon dioxide in the atmosphere is:
1. increasing
2. decreasing
3. holding steady
4. fluctuating wildly

Subtopic:  Mineral Cycling & Ecosystem Services (OLD NCERT) |
 82%
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The ecosystem that can survive in the absence of the Sun would be:

1.tropical rainforest2.tundra
3.benthic ocean4.desert

Subtopic:  Components & Types of Ecosystems | Energy Flow |
 81%
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An important feature of the phosphorus cycle is that its reservoir is in:
1. aquifers
2. soil and rocks
3. the atmosphere
4. the sun

Subtopic:  Mineral Cycling & Ecosystem Services (OLD NCERT) |
 94%
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