Multiple Choice Questions

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Which of the following factor is biotic

  • Photoperiod

  • CO2 content to the soil

  • Texture and porosity of soil

  • Rainfall


B.

CO2 content to the soil

CO2 content to the soil is a biotic factor because CO2 is released through the plants in soil by respiration process


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Given below is one of the types pyramids.

This type represents

  • pyramid of numbers in a grassland

  • pyramid of biomass in a fallow land

  • pyramid of biomass in a lake

  • energy pyramid in a spring


Assertion: In tropical rain forests, O-horizon and A-horizon of soil profile are shallow and nutrient-poor.

Reason: Excessive growth of micro-organisms in the soil depletes its organic content.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


July 11 is observed as:

  • World population day

  • No tobacco day

  • World environment day

  • World health day


Biological Oxygen Demand (BOD) is a measure of

  • industrial wastes poured into water bodies

  • extent to which water is polluted with organic compounds

  • amount of carbon monoxide inseparably combined with haemoglobin

  • amount of oxygen needed by green plants during night


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Assertion : In a food chain members of successive higher levels are fewer in number.

Reason : Number of organisms at any trophic level depends upon the availability of organisms which serve as food at the lower level.

  • If both Assertion and Reason are true and the reason is the correct explanation of the assertion

  • If both Assertion and Reason are true but the reason is not the correct explanation of the assertion

  • If Assertion is true statement but Reason is false

  • If both Assertion and Reason are false statements


The driving force of an ecosystem is :

  • producers

  • biomass

  • solar energy

  • grassland


Acid rain is due to increase in atmospheric concentration of :

  • Ozone

  • CO2 and CO

  • SO3 and CO

  • SO2 and nitrogen oxide


The pyramid of energy-in a forest ecosystem is

  • always upright

  • always inverted

  • both (a) and (b)

  • none of the above


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Identify which one of the following is an example, of incomplete ecosystem?

  • Grassland

  • Cave

  • River

  • Wetland


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