Answer: The combination produced is RRtt.
The combination rrTt does not appear in this punnett square.
Explanation:
As the problem does not indicate more information, I assume that punnett square is made between two RRtt genotypes. It can produce gametes that have the alleles Rt. A gamete is a sexual cell (egg or sperm) that has only one allele of each gene. And, each gamete codes for a different gene. Since here we have two different types of alleles (R and t), it is a dihybrid cross.
<u>A Punnett square is a diagram used to predict the genotypes of a cross or breeding experiment.</u> It is used to determine the genotypes and phenotypes of the offspring. To do it, you have to label the rows with one parent's gametes and label the columns with the other parent's genotype. Then, have each box inherit letters from its row and column, and interpret the results.
Then, the punnett square (shown in the picture) will be between RRtt and RRtt whose gametes can only be Rt, so Rt x Rt will be made.
The result in an offspring which will be 100% RRtt, and there is no rrTt combination here because non of the parents have an r allele, then none of the children can inherit it.
To have an offspring where rrTt genotype is shown, a different genotype must be used, in which both parents must have at least one r allele and one t allele. For example, it could be Rrtt x rrTt.
