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Biology · 2023 · 5 marks
CBSE 2023 · Region 5 · Set 1 · Q32
(a) Name and describe the steps involved in the technique widely used in forensics that serves as the basis of paternity testing in case of disputes.
(a)
Name and describe the steps involved in the technique widely used in forensics that serves as the basis of paternity testing in case of disputes.
OR
(b)
It is sometimes observed that the $\displaystyle \mathrm{F}_{1}$ progeny has a phenotype that does not resemble either of the two parents and has intermediate phenotype. Explain by taking a suitable example and working out the cross upto $\displaystyle \mathrm{F}_{2}$ progeny.
Marking-scheme solution
(a)
DNA fingerprinting
Steps
(i)
Isolation of DNA
(ii)
Digestion of DNA by restriction endonuclease enzyme
(iii)
Separation of DNA fragments, by electrophoresis
(iv)
Transferring of separated DNA fragments to synthetic membrane such as nitrocellulose or nylon.
(v)
Hybridization, using labelled VNTR probe.
(vi)
Detection of hybridized DNA fragments by autoradiography
OR(b) Incomplete Dominance
Snapdragon flower / Dog flower / Antirrhinum
\[\begin{array}{ccc}
RR & \times & rr\\
(\text{Red}) & \downarrow & (\text{White})\\
& Rr\ (\text{Pink}) & \\
& \downarrow \text{Selfing} &
\end{array}
\]
| R | r | |
| R | RR Red | Rr Pink |
| r | Rr Pink | rr White |
Phenotype - Red : Pink : White
$\displaystyle 1\ :\ 2\ :\ 1$
Genotype - RR : Rr : rr
$\displaystyle 1\ :\ 2\ :\ 1$
All Molecular Basis of Inheritance questions2023 question paperNCERT solutions: Molecular Basis of InheritancePractice Molecular Basis of Inheritance →
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CBSE Class 12 Biology past-paper question from the 2023 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.