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) Litter and detritus
(f) Primary and secondary productivity .

Explanation

(a) Refer to article 14.5.3, page V/1 04.
(b) Production refers to the process of synthesis of organic compounds from inorganic substances such as carbon dioxide, water and minerals utilizing generally the sunlight. It is mainly done by plants.
Decomposition, on the other hand, is the process of breaking down a substance into its constituent parts. It is brought about by reducer organisms (bacteria, fungi of decay).
(c) When the number of producer organisms or their biomass is maximum in an ecosystem and these decrease progressively at each trophic level in a food chain, we get upright pyramids. On the contrary, when number of individuals or their biomass at producer level is minimum and it increases progressively at each trophic level in a food chain, then we get inverted pyramid.
(d) Refer to articles 14.5 and 14.6, pages V/103, V/107.
(e) Dead remains of plants and animals constitute the detritus. It is differentiated into litter fall (above ground detritus) and below ground detritus.
Litter, on the other hand, is above ground detritus. The dead remains of plants (leaves, bark, flowers etc.) and dead remains of animals, their faecal matter that fall on the surf ace of earth in terrestrial ecosystem is litter (above ground detritus).
(f) Primary productivity refers to the rate of production of biomass or organic matter per unit area over a time period by the producers in an ecosystem. On the secondary productivity refers to rate of production of biomass or organic matter over a time period by the consumer.