Energy Flow Through Ecosystems

Decomposers are the part of biotic component of an ecosystem. They are heterotrophic (saprotrophs) microconsumers that feed on dead bodies of organisms and organic wastes of living organisms.

Step 1: Understanding xerarch succession.
Xerarch succession begins in dry, barren areas such as bare rocks where soil is absent.
Step 2: Pioneer community.
Lichens are the first colonizers as they can survive harsh, dry conditions and initiate soil formation.
Step 3: Progressive stages.
Mosses grow next on thin soil, followed by herbs, shrubs, and finally trees as soil depth and moisture increase.
Step 4: Climax community.
Trees form the climax community, representing a stable ecosystem.

Step 1: Role of saprophytes.
Saprophytes feed on dead and decaying organic matter.
Step 2: Ecological classification.
They break down complex organic substances into simpler forms and recycle nutrients.
Step 3: Correct classification.
Thus, saprophytes are classified as micro-consumers or decomposers.

Step 1: Understanding the carbon cycle.
The carbon cycle involves the movement of carbon through various reservoirs. The largest reservoir of carbon is the ocean, which stores carbon in dissolved forms and marine organisms.
Step 2: Analyzing the options.
(A) Ocean: Correct — The ocean holds the largest amount of carbon, primarily in the form of dissolved CO2.
(B) Detritus in soil: Incorrect — While the soil holds some carbon, it is not the largest reservoir.
(C) Plants and animals: Incorrect — Plants and animals hold carbon, but they are smaller reservoirs compared to the ocean.
(D) Atmosphere: Incorrect — The atmosphere holds a smaller amount of carbon compared to the ocean.
Step 3: Conclusion.
The correct answer is (A) Ocean, as it is the largest reservoir of carbon.