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In a dihybrid cross between RrTt and RRtt, what are the genotype and phenotype ratios of the offspring, assuming R and T are dominant?

I did the punnett square but can't figure out the branch diagram

Respuesta :

80willjr
this punnett square will require you to do 4 letters on the top and the right. usually is 2 there are around 16 possible combinations at most.
samueladesida43

Answer:

Phenotypic ratio=1:1

Genotypic ratio=1:1:1:1

Explanation:

This is a dihybrid cross involving two genes R and T where the alleles R and T are dominant over alleles r and t respectively I.e. allele R and T will mask the expression of alleles r and t respectively, in a heterozygous state.

In a cross between RrTt and RRtt, meiotic division will occur and each parental's allele will separate into gametes independently of one another. The following possible gametes produced are:

RrTt: RT, Rt, rT and rt

RRtt: Rt, Rt, Rt, and Rt

According to the punnet square (see attached image), 16 possible offsprings will be produced with the following genotypes:

4 RRTt, 4 RRtt, 4 RrTt, and 4 Rrtt

Hence, the genotypic ratio will be 1:1:1:1

Among the 16 possible offsprings, 8 will have a genotype in which both R and T are expressed, while 8 will have a genotype where only R is dominant and t is recessive (tt). Hence, only two phenotypes will be produced in equal ratio 1:1.

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