Tag: deviation from mendelism

Questions Related to deviation from mendelism

What percentage of progenies would have broad leaves and pink flower in F2 generation of Snapdragon if the first trait follows the law of dominance and the other shows incomplete dominance?

botany classical genetics incomplete dominance deviation from mendelism inheritance

  1. 37.5%

  2. 56.25%

  3. 62.5%

  4. 12.5%

Show answer
Correct Option: A
Explanation:

Assume that the broad shape of leaves is governed by alleles B,b where 'B' represents dominant allele for broad leaves. Similarly, 'R' and 'r' are alleles for the colour of the flower. 'RR' progenies show red colour,' rr' progenies show white colour and 'Rr' progenies show pink colour due to incomplete domination.


Dihybrid cross for F2 generation in Snapdragon can be shown as below - 

 Gamete type  BR  Br  bR  br
 BR  BBRR  BBRr  BbRR   BbRr
 Br  BBRr BBrr   BbRr  Bbrr
 bR  BbRR   BbRr bbRR   bbRr
 br   BbRr  Bbrr  bbRr  bbrr
We can see, 6 out of 16 ( Genotypes BbRr and BBRr ) progenies will have broad leaves and pink flower which is equal to 37.5%.
So, the correct option is '37.5%'.