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Science · 2022 · 2 marks
CBSE 2022 · Region 1 · Set 1 · Q5
(a) What is variation? List two main reasons that may lead to variation in a population.
What is variation ? List two main reasons that may lead to variation in a population.
(i)
In a cross between violet flowered plants and white flowered plants, state the characteristics of the plants obtained in the $\displaystyle \mathrm{F}_{1}$ progeny.
(ii)
If the plants of $\displaystyle \mathrm{F}_{1}$ progeny are self-pollinated, then what would be observed in the plants of $\displaystyle \mathrm{F}_{2}$ progeny?
(iii)
If $\displaystyle 100$ plants are produced in $\displaystyle \mathrm{F}_{2}$ progeny, then how many plants will show the recessive trait?
Marking-scheme solution
The differences in the traits shown by the individuals of a species.
Two reasons :
i) Inaccurate / Error in DNA copying
ii) Sexual reproduction
(b)
OR
(i) F1 Progeny : Violet flowered plants
(ii) F2 Progeny : Violet as well as white flowered plants
(iii)
$\displaystyle 25$ plants
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CBSE Class 10 Science past-paper question from the 2022 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.