Q6 of 21 Page 9

Why is variation beneficial for the species, but not necessarily for the individual? ( CBSE 2013)

Accumulation of variation ina species enables them to adapt according to the change and the new needs. This provides a survival advantage to the species. But an individual does not get any advantage due to the variation that takes pale on him. Thus, variation is beneficial for a species, but not necessary for the individual.

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4 A blue colour flower plant denoted by BB is crossbred with a white colour flower plant denoted by ww.
(a) State the colour of flower we would expect in their F1 progeny.
(b)Write the percentage of plants bearing white flower in F2 generation when the flowers of F1 plants were selfed.
(c) State the expected ratio of the genotype BB and Bw in the F2 progeny. ( CBSE 2013, 2012) 5

A cross was carried out between a pure bred tall pea plant and a pure bred dwarf pea plant and F1 progeny was obtained. Later, the F1 progeny was salted to obtain F2 progeny. Answer the following questions:(a) What is the phenotype of the F1progeny andwhy?

(b) Give the phenotypic ratio of theF2 progeny.


(c) Why is the F2 progeny different from the F1 progeny? ( CBSE 2013, 2012)

 7

‘‘Evolution and classification of organisms are interlinked.’’ Give reasons to justify this statement. ( CBSE 2017)

 8

Will geographical isolation be a major factor in the speciation of a self-pollinating plant species? Why or why not? ( CBSE 2013, 2012)