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Biology · 2025 · 5 marks
CBSE 2025 · Region 1 · Set 3 · Q31
Student to attempt either option-(A) or (B). (A) (i) You are given axial pea flowers with violet colour whose genotypes are unknown. How would you…
Student to attempt either option-(A) or (B).
(A)(i)
You are given axial pea flowers with violet colour whose genotypes are unknown. How would you find the genotype of these plants? Explain with the help of cross.
(ii)
Explain Haplodiploidy in honey-bees.
OR
(B)
Explain the steps of DNA fingerprinting that will help in processing of the two blood samples R and S picked up from the crime scene.
Marking-scheme solution
(i)
Case I : AAVV X aavv
Result : $\displaystyle 100$% axial Violet
Genotype : AAVV
Case II : AaVV X aavv
Result : $\displaystyle 50$% axial violet, $\displaystyle 50$% terminal violet
Genotype : AaVV
Case III : AAVv X aavv
Result : $\displaystyle 50$% axial violet, $\displaystyle 50$% axial white
Genotype : AAVv
Case IV : AaVv X aavv
Result : $\displaystyle 50$% axial violet, $\displaystyle 50$% terminal white
Genotype : AaVv
(ii)
In Honey bee males are haploid, females are diploid
Steps of DNA fingerprinting:
1. Isolation of DNA from both the samples R and S
2. Digestion of the DNAs of both the samples same restriction endonucleases
3. Separation of DNA fragments by electrophoresis by placing them in different wells of the agarose gel
4. Transferring (blotting) of separated DNA fragments to synthetic membranes, such as nitrocellulose or nylon.
5. Hybridisation using labelled VNTR probe followed by detection of hybridised DNA fragments by autoradiography
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