The movement of nutrient elements through the various components of an ecosystem is called

1. A

   Bio-geo-chemical cycle

   (a) Bio-geo-chemical cycle. Movement of nutrient elements through biotic and abiotic components of an ecosystem is the biogeochemical cycle. That is the official key.

2. B

   Bio-geological cycle

   (b) Bio-geological cycle. Not the standard term; geology alone does not name the nutrient loop.

3. C

   Ecological succession

   (c) Ecological succession. Succession is the directional change of communities in time, not nutrient circulation.

4. D

   Biological cycle

   (d) Biological cycle. Too vague; it omits the geological/abiotic reservoir that biogeochemistry includes.

Summary. Official key is (a). Nutrient flow through ecosystem components is the bio-geo-chemical cycle, not succession or a merely ‘biological’ cycle.