Question

How can the 9:3:3:1 ratio be converted into 9:7 and 15:1 ratios?

Answer 1

The ratio 9:3:3:1 is the normal dihybrid phenotypic ration in Mendelian genetics.

However, this ratio changes in case of epistasis.

They can be converted by epistasis.

The ratio 9:7 is a modified version of the standard ratio and it represents duplicate recessive epistasis or complementary epistasis.

Here, recessive alleles present at both the loci suppresses the expression of alleles which are dominant.

An example is the sweet pea flower colour.

The ratio 15:1 represents duplicate dominant epistasis.

Here, the expression of the recessive alleles are suppressed by the dominant alleles at the two loci.

An example is the awn character present in rice.

Answer 2

"The given ratio is 9:3:3:1

In order to convert the ratio into 9: 7,

We need to take the sum of the digits after 9, that is, 3+3+ 1 = 7

Therefore the final ratio is

9: 7

Similarly,

In order to make the ratio 15: 1,

We need to take the sum of the first three digits, that is, 9+3+3= 15

Therefore the final ratio is 15: 1.

"