Which one of the following is the best description of the term ‘ecosystem’? 
(a) A community of organisms interacting with one another.
(b) That part of the Earth which is inhabited by living organisms.
(c) A community of organisms together with the environment in which they live.
(d) The flora and fauna of a geographical area.
Which one of the following terms describes not only the physical space occupied by an organism, but also its functional role in the community of organisms? 
(b) Ecological niche
(d) Home range
The Millennium Ecosystem Assessment describes the following major categories of ecosystem services provisioning, supporting, regulating, preserving and cultural. Which one of the following is supporting service? 
(a) Production of food and water
(b) Control of climate and disease
(c) Nutrient cycling and crop pollination
(d) Maintenance of diversity
Within biological communities, some species are important in determining the ability of a large number of other species to persist in the community. Such species are called _____ 
(a) Keystone species
(b) Allopatric species
(c) Sympatric species
(d) Threatened species
Which one of the following is the correct sequence of ecosystems in the order of decreasing productivity? 
(a) Oceans, lakes, grasslands, mangroves
(b) Mangroves, oceans, grasslands, lakes
(c) Mangroves, grasslands, lakes, oceans
(d) Oceans, mangroves, lakes, grasslands