591: 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?
(a) Ecotone
(b) Ecological niche
(c) Habitat
(d) Home range
592: Natural rubber is a plant product which is chemically known as
(a) Mucilage
(b) Gum
(c) Latex
(d) Resin
593: Which of the following is a cash crop ?
(a) Groundnut
(b) Wheat
(c) Rice
(d) Gram
594: Where was the selection of suitable candidates for a particular job first started through competitive examinations?
(a) China
(b) Great Britain
(c) U.S.A.
(d) Germany
595: Consider the following statements :
Chlorofluorocarbons, known as ozone-depleting substances, are used
1. in the production of plastic foams
2. in the production of tubeless tyres
3. in cleaning certain electronic components
4. as pressurizing agents in aerosol cans
Which of the statements given above is/are correct?
(a) 1, 2 and 3 only
(b) 4 only
(c) 1, 3 and 4 only
(d) 1, 2, 3 and 4