Is the common edible mushroom an autotroph or a heterotroph?
Common edible mushroom (Agaricus) is achlorophyllous (does not possess chlorophyll) and is a heterotroph.
Why are oceans least productive?
Oceans are least productive because
(i) There is insufficient radiation as sunlight decreases with the increasing depth of the ocean.
(ii) Oceans are nitrogen deficient which is an important nutrient for plants.
(iii) Conditions of high salinity which is not favourable for all plants.
(iv) there is no substratum to support plants.
Why is the rate of assimilation of energy at the herbivore level called secondary productivity?
The rate of assimilation of energy at herbivore level is called secondary productivity because the biomass available to the organisms of next trophic level (consumer) for further consumption is a resultant of the primary productivity which is formed by autotrophs (plants).
Why are nutrient cycles in nature called biogeochemical cycles?
Nutrient cycles are called biogeochemical cycles because ions/molecules of a nutrient are transferred from the environment (rocks, air and water) to organisms (life) and then brought back to the environment in a cyclic pathway. The literal meaning of biogeochemical is bioliving organism and georocks, air and water.
Give any two examples of xerarch succession.
Xerarch succession of ecological communities originates in extremely dry conditions such as sand deserts and rock deserts (as there is no water and the substratum does not absorb rain water).