Importance of NCERT Exemplar Class 12 Biology:
The difficulty level of these questions is quite higher than the questions usually given at the end of the chapter of NCERT book. It will help students to enhance their preparation level for CBSE board and competitive examinations.
Few problems along with their solutions from this chapter are given follows:
Q.┬аWhich of the following is not a cause for loss of biodiversity?
(a) ┬аDestruction of habitat
(b) Invasion by alien species
(c) ┬аKeeping animals in zoological parks
(d) Over-exploitation of natural resources
Ans.┬а(c) Keeping animals in zoological parks
Keeping animals in zoological parks helps in conservation of biodiversity. It gives a natural and safe environment to the protected animals.
Q.┬аWhat characteristics make a community stable?
Ans.┬аThe characteristics that make a community stable are
(i)┬а┬а┬а┬а Less variation in productivity from year to year.
(ii)┬а┬а Resistance or resilience to occasional disturbances (natural or man-made)
(iii) Resistance to invasions by alien species.
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Q.┬аDefine the terms (i) Bioprospecting (ii) Endemism
Ans.┬а(i) Bioprospecting is a term that describes the process of discovery and
commercialisation of new products based on biological resources.
(ii) Endemism┬аis the condition┬аunder which some species are restricted to a particular region only.
Q.┬аDiscuss one example, based on your day-to-day observations, showing how loss of one species may lead to the extinction of another.
Ans.┬аCo-extinction is the extinction of two mutually related or interested species for instance extinction of a host fish leads to the extinction of all those parasites exclusively found on it. Another example is plant pollinator mutualism, where extinction of one leads to the extinction of other.
Insect, aphids are polyphagous (feed on more than one plant species) or monophagous (feed on a particular species of plant). Monophagous insects may become extinct, if the plant species upon which they feed becomes extinct.
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