Question

Blue flower is dominant to yellow flower. Tall plant is dominant to short. Cross BbTt * BbTt. What precenetage of the offsprings are expected to be heterozygous for both traits?

Answer 1

Answer:

The correct answer would be - 25%.

Explanation:

It is given that the Blue flower is dominant over the yellow flower which means Blue is represented by allele B here and allele b for yellow and Bb is a heterozygous case with a blue phenotypic character. Similarly, the Tall plant is dominant over short and represented by T and t respectively.

BbTt is a heterozygous condition and a cross with itself will produce :

Gametes: BT Bt bT and bt

          BT       Bt       bT       bt

BT     BBTT   BBTt   BbTT   BbTt

Bt      BBTt    BBtt    BbTt   Bbtt

bT     BbTT   BbTt    bbTT   bbTt

bt      BbTt     Bbtt    bbTt     bbtt

Here 4 out of 16 offspring are heterozygous for both traits represented by bold alphabets. Therefore the correct answer is 25%