A. Lichens are pioneer species on rocks.
R. They secrete acids to dissolve rocks, helping in weathering and soil formation,
[A] A and R are both correct.
[B] A and R are both incorrect,
[C] A is correct but R is incorrect. [D] R is correct but A is incorrect.
Find out total number of true statements from the following.
(A) Primary succession, is a very slow process, taking thousands of years for the climax to be reached.
(B) All succession whether taking place in water or land, proceeds to a similar climax community, the mesic.
(C) As succession proceeds, the number and types of animals and decomposers also change
(D) Saprophytes are not given any place in the ecological pyramids even though they play a vital role hi the ecosystem.
[C] 3 [D] 4
The amount of nutrients such as carbon, nitrogen, phosphorus, calcium, etc., present in the soil at any given time is referred to as:
[A] Standing state
[B] Standing crop
[C] Hydrarch [D] Xerarch
Nutrient cycling is known as:
[A] Biogeochemical cycle
[B] Calvin cycle
[C] Hatch-slack pathway [D] Krebs cycle
[A] Vary according to type of ecosystem
[B] Vary on seasonal basis
[C] Both (a) and (b) [D] None of the above
How many types of nutrient cycles are there?
[C] 3 [D] 4
The following elements shows gaseous type of nutrient cycles except:
[C] Oxygen [D] Phosphorus
The following factors regulate the release of nutrients into the atmosphere:
[A] Soil and moisture
[C] Temperature [D] All of these
Which nutrients flows through the sedimentary cycle?
[C] Both (a) and (b) [D] Carbon
What percentage of the dry weight of an organism does carbon constitute?
[C] 49% [D] 35%
What percentage of global carbon does the atmosphere contain?
[C] 1% [D] 10%
How much carbon is fixed approximately in biosphere annually through the process of photosynthesis?
[B] 4x 1010kg
[C] 4×108kg [D] 4×1020kg
Which of the following majorly regulates the amount of CO, in the atmosphere?
[A] Respiratory activities of the producers and consumers
[C] Burning of fossil fuel [D] Oceanic reservoir
Human activities mainly influence the:
[A] Carbon cycle
[B] Nitrogen cycle
[C] Phosphorus cycle [D] Sulphur cycle
Phosphorus is a major constituent of:
[A] Biological membrane
[B] Nucleic acids
[C] Cellular energy transfer system [D] All of the above