1. What does destruction refer?

137. What does regulatory function of ecosystem relate?
A) regulate essential ecological processes and life support systems through bio-
geochemical cycles and other biospheric processes
B) provide refuge and a reproduction habitat to wild plants and animals
C) contribute to the maintenance of human health by providing opportunities for reflection, 
spiritual enrichment, cognitive development, recreation and aesthetic experience
D) the distribution of various species and ecosystems geographically and throughout 
geological time and space
E) Photosynthesis and nutrient uptake by autotrophs converts energy, carbon dioxide, 
water and nutrients into a wide variety of carbohydrate structures which are then used by 
secondary producers to create an even larger variety of living biomass
138
. Choose the correct definition for functional unit of ecosystem “productivity”
A) It is the sequential process through which energy flows from one trophic level to another
B) It is the process of breakdown of dead organic material. The top-soil is the major site for 
decompositionIn an ecosystem nutrients are consumed and recycled back in various forms 
for the utilisation by various organisms
C) The energy captured from the sun flows from producers to consumers and then to 
decomposers and finally back to the environment
D) It refers to the biomass production
E) In an ecosystem nutrients are consumed and recycled back in various forms for the 
utilisation by various organisms
139. Foremost among the immediate threats to ecosystem services are:
A) Destruction of natural habitats

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B) Climate change
C) Invasion of non-native species
D) Physical pollutants
E) Brownification
140. The Biosphere 2 experiment attempting to duplicate the earth's environment