In tomatoes, there are two alleles for the height gene. The tall allele is dominant over the short allele. You cross a heterozygous plant with a homozygous recessive plant. What phenotypes do you expect in their offspring?
Tt x tt ==> 1 Tt: 1tt which is 1 Tall : 1 Short
To determine the phenotypes of the offspring, let's represent the alleles for the height gene using letters: T for tall (dominant allele) and t for short (recessive allele).
Given that the tall allele (T) is dominant over the short allele (t), the genotype of the heterozygous plant would be Tt, and the genotype of the homozygous recessive plant would be tt.
To determine the phenotypes, we can use a Punnett square to cross these genotypes:
| T | t |
-----------------
T | TT | Tt |
t | Tt | tt |
From the Punnett square, we can see that there are two possible genotypes in the offspring: TT and Tt.
Phenotypically, plants with the genotype TT (homozygous dominant) will have the tall phenotype. Plants with the genotype Tt (heterozygous) will also have the tall phenotype since the tall allele is dominant over the short allele.
Therefore, we expect all the offspring to have the tall phenotype.
To determine the phenotypes of the offspring, we need to first understand the genetic makeup of the parent plants. Let's denote the tall allele as "T" (dominant) and the short allele as "t" (recessive).
The cross involves a heterozygous plant (Tt) and a homozygous recessive plant (tt).
To determine the possible genotypes and phenotypes of the offspring, we can use a Punnett square. Here's how you can set up the Punnett square:
| T | t
--------------
T | TT | Tt
--------------
t | Tt | tt
In this square, the rows represent the alleles from the heterozygous plant (Tt), and the columns represent the alleles from the homozygous recessive plant (tt).
Now, let's analyze the potential outcomes:
1. TT: This offspring will inherit the dominant "T" allele from the heterozygous parent and another "T" allele from the homozygous recessive parent. As a result, the phenotype will be tall because the dominant allele determines the height.
2. Tt: This offspring will inherit the dominant "T" allele from the heterozygous parent and the recessive "t" allele from the homozygous recessive parent. Again, the phenotype will be tall since the dominant allele determines the height.
3. Tt: Similarly, this offspring will have the same genotype as the previous case (Tt) and will also exhibit a tall phenotype.
4. tt: This offspring will inherit the recessive "t" allele from both parents. Since the recessive allele is responsible for the short phenotype, this offspring will be short.
So, in the offspring, you can expect three tall plants (Tt) and one short plant (tt).