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In this Punnett square, what is the ratio of homozygous to heterozygous offspring? In the Punnett square, what percentage of the offspring are homozygous recessive?

In this Punnett square what is the ratio of homozygous to heterozygous offspring In the Punnett square what percentage of the offspring are homozygous recessive class=

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ali015
In a Punnet square, the alleles (one letter: either T or t, here) go horizontally across the top for one parent and vertical down the left for the other parent. In the 2 by 2 square (outlined in blue) are the possible offsprings. The genotypes (two letters: TT, Tt, or tt) of the offspring is the combination of the two parent alleles that intersect in that square.

Start by filling in the rest of the box!
1) Since you know the bottom right square is tt, that means both alleles must be t. You already have the allele of the parent on the left filled in, so fill in the top one with t (shown in green).

2) Since you know the top left square in the 2 by 2 box is Tt, one allele from the parent is T and the other allele is t. You're already given T by the top parent, so fill in the box for the left parent with t (shown in purple).

3) Finally fill in the top right box in the 2 by 2. The top parent donates a t allele (green) and the left parent also donates a t allele (purple). The genotype is tt.

Now back to the questions:
1) Homozygous offspring means that for it's genotype, both alleles are the same: either TT or tt. Heterozygous means that the alleles are different: Tt.

Looking at the 2 by 2 box, which shows your possible offspring, two are Tt (heterozygous) and two are tt (homozygous). The ratio is 2:2, which is the same as 1:1.

2) For homozygous alleles, you can either have homozygous dominant or recessive. Usually the problem tells you which allele is dominant, but the dominant allele is usually shown with a capital letter, or T in this problem! That means homozygous dominant is two capital T's, TT, and homozygous recessive is two lowercase t's, or tt. We will be looking for how many are homozygous recessive, or tt.

Looking at the 2 by 2 box, two of the four offspring have the genotype tt. 2/4 = 50%.

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Answer:
1) 1:1
2) 50%
Ver imagen ali015
Histrionicus

Answer:

1. The Ratio of homozygous to heterozygous: 1:1 2. Percentage of homozygous recessive: 50%

Explanation:

In Punnett square box we put alleles of one parent in top horizontally- T is given here and another parent in vertically- t is given.

Alleles of parents cross to produce offspring. First of all we need to find what are the rest of the alleles of parents, in bottom right offspring is tt that means the second allele of the horizontal parent must be t too.

And now as Tt offspring is given on the top left so the other allele for vertical parent must be t.

As now we get all alleles for parents now the cross between t from horizontal and t from vertical parent cross n produce tt.

So,  we have four offspring- Tt, tt, Tt, and tt where tt is homozygous recessive and Tt is heterozygous.

The Ratio between homozygous and heterozygous is 2/2= 1/1 or 1:1, the percentage of homozygous recessive is 2/4×100 = 50%

Ver imagen Histrionicus

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