At the trophic level of consumers, the rate at which food energy is assimilated, is called:
1. Secondary productivity
2. Gross primary productivity
3. Net primary productivity
4. None of these
Secondary production represents the formation of living mass of a heterotrophic population or group of populations over some period of time. It is the heterotrophic equivalent of net primary production by autotrophs.
The term "detritivore" includes
2. primary consumers
3. secondary consumers
Read page 243, Xll NCERT
Net primary productivity is the gross primary productivity less
1. that which is consumed by herbivores
2. that which is consumed by producer in metabolism
3. secondary productivity
4. loss due to mortality
Read page 243, XII NCERT
The major reservoir for phosphorous is
(b) Soil and rocks
(c) The atmosphere
Read page 254, XII NCERT
The accumulation of herbivore biomass in an ecosystem is an example of
1. biogeochemical cycles
3. net primary productivity
4. secondary productivity
Read page 243, Xll NCERT
Which of the following pyramids can never be inverted in a natural ecosystem?
1. pyramid of numbers
2. pyramid of energy
3. pyramid of biomass
4. all can be inverted
Read page 249, XII NCERT
The earth is an open system with respect to
4. all of the above
A constant input of energy is required to keep the stability of the ecosystem and overcome any entropy. This input is ultimately provided by the sun.
Plants capture approximately __________________ of the sun's energy while other trophics levels capture about _________________ of the energy available to them in their food.
1. 1%, 10%
2. 10%, 60%
3. 10%, 1%
4. 60%, 10%
Read page 245, Xll NCERT
Which trophic level is incorrectly defined?
1. Carnivores- secondary or tertiary consumer
2. Decomposer- microbial heterotrophs
3. Herbivores - primary consumer
4. Omnivores - Molds, yeast and mushrooms
Read page 246, Xll NCERT
Nitrogen gas makes up nearly 80% of Earth's atmosphere, yet nitrogen is often a limiting factor for plant growth. Why ?
1. The atmospheric form of nitrogen cannot be used by plants.
2. Nitrifying bacteria remove usable nitrogen from the soil more repidly than plants can absorb it.
3. Atmospheric nitrogen dissolves readily in the soil but is washed out with every rainfall.
4. Plants must absorb nitrogen through their roots, which are not in contact with the atmosphere.
The dinitrogen is a tough molecule with triple covalent bond. Only prokaryotes have the capability to fix it.