Question

Given below is a simplified model of phosphorus cycling in a terrestrial ecosystem with four blanks (A-D). Identify the blanks.

	A	B	C	D
(1)	Rock minerals	Detritus	Litter fall	Producers
(2)	Litter	Producers	Rock minerals	Detritus
(3)	Detritus	Rock minerals	Producer	Litter fall
(4)	Producers	Litter fall	Rock minerals	Detritus

• A. (3)
• B. (4)
• C. (2)
• D. (1)

Answer 1

The correct option is A (3)

The given model represents the phosphorus cycle which is an example of the sedimentary cycle.

Rock is the natural reservoir of phosphorus.

Minor amounts of phosphorus get dissolved in the soil solution due to the weathering of rocks which is absorbed by the roots of plants.

Herbivorous animals obtain phosphorus by consuming plants and carnivores obtain it by feeding on herbivores.

Decomposition of the dead plants and animals (detritus) by phosphate-solubilising bacteria also releases phosphorus. This way the phosphorus is cycled.

A - Detritus, B - Rock minerals, C - Producer, D - Litter fall

So, the correct answer is option C.