Question

19. a) in a dihybrid cross 1600 plants were
obtained. Find out the number of plants
having genotype
RRYy and rryy respectively,​

Answer 1

Answer:

Dihybrid cross is a cross between two different lines/genes that differ in two observed traits. In the Mendelian sense, between the alleles of both these loci there is a relationship of complete dominance - recessive. In the example pictured to the right, RRYY/rryy parents result in F1 offspring that are heterozygous for both R and Y (RrYy).

Now the question demands the frequency of Round and yellow coloured seeds in F2 generation, which will be possible if the progeny have the genotype of R_Y_, where the blank spaces can be filled by either R or r. The probability of finding a R_ or Y_ genotype is 3/4. So the cumulative result will be (3/4) X (3/4).