Secondary producers are

Select the incorrect statement from the following.

The primary succession in a sere is

What is true about the phosphorus cycle?
$I.$ Rocks are the natural reservoirs of phosphorus.
$II.$ Weathering of sedimentary rocks makes phosphate available to the soil.
$III.$ Herbivores and carnivores obtain phosphorus from plants directly or indirectly.
Choose the correct option.

Select the incorrect statement for the detritus food chain.

The 'Reed-swamp' stage refers to which of the following?