question_answer 6)

Distinguish between : (a) Grazing food chain and detritus food chain. (b) Production and decomposition. (c) Upright and inverted pyramid. (d) Food chain and food web. (e) Detritus and litter. (f) Primary and secondary productivity.  

Answer:

(a) Characters Grazing food chain Detritus food chain 1. Primary source of energy Solar radiations. Detritus. 2. First trophic level All herbivores. Detritivores (a mixed group in terms of trophic levels and may be herbivores, omnivores and primary carnivores). 3. Size Long-sized chains. Small-sized chains. 4. Examples Predatory food chains on land and in water. Mangrove fallen leaves in brackish zone south Florida. (b) Production is the process of formation of complex organic compounds or formation of biomass by the organisms of a particular trophic level. It is called primary production at the level of producers while is called secondary production at the level of consumers. On the other hand, decomposition is the process of breaking of complex organic compounds into simpler and inorganic compounds by the microscopic organisms called decomposers e.g. bacteria and fungi. (c) Upright pyramid is characterized by having a-broad base and tapering towards the tip so is triangular- shaped e.g. pyramid of number of a predatory food chain in a grassland or a pond ecosystem. In this pyramid, the size of organisms increases with each trophic level from the producer level to the top carnivore level, while their number decreases in a food chain. On the other hand, an inverted pyramid is characterized by haying narrow base which broadens towards the top so is like an inverted triangle e.g. pyramid of number of a parasitic food chain on an oak tree. (d) A food chain is a series of trophic levels in which there is repeated eating and eaten by to transfer the food energy, while a food web is a network formed by interconnection of many food chains to provide alternative pathways of food availability. (e) Detritus is the dead organic matter formed of excreta of animals and dead bodies of plants (e.g. fallen leaves, bark, flowers, etc.) and animals and represents the initial stage of decomposition, while litter is the partially decomposed organic matter of detritus by specific enzymatic actions. (f) Primary productivity is the amount of food energy formed or biomass produced by the process of photosynthesis or chemosynthesis at the autotroph or producer level while secondary productivity is the amount of assimilated food energy at the trophic levels of consumers.