The energy flow in an ecosystem is unidirectional '. Justify the statement .

Read the following statements and select the correct ones. (i) A given species may occupy more than one trophic level in the same ecosystem at the same time. (ii) Productivity of an aquatic ecosystem is less than that of a terrestrial ecosystem. (iii) Producers constitute the first trophic level of a detritus food chain. A) i and ii B) ii and iii C) i and iii D) i, ii and iii

Justify the following statement in terms of ecosystem dynamics. 'Nature tends to increase the gross primary productivity, while man tends to increase the net primary productivity'.

Study the given flow chart and select the correct statement regarding this. (i) It represents phosphorus cycling in a terrestrial ecosystem. (ii) It represents phosphorus cycling in an aquatic ecosystem. (iii) Natural resenvoir of phosphorus is phosphate rocks. (iv) There is no repiratory release of phosphorus into atmosphere. (v) Gaseous exchange of phosphorus between organisms and enviornment occurs to a considereable extent.

Study the following statements and select the incorrect ones. (i) Pyramids of energy and yearly biomass production can never be inverted, since this would violate the laws of thermodynamics. (ii) Pyramids of standing crop and numbers can be inverted, since the number of organisms at a time does not indicate the amount of energy flowing through the system. (iii) There are certain limitations of ecological pyramids such as they do not take into account the same species belonging to two or more trophic levels. (iv) Saprohytes are not given any place in ecological pyramids even though they play a vital role in the ecosystem.