A 3:1 ratio of tall to short plants in the F2 generation lends support to the principle of ________________.
Dominant:recessive
The 3:1 ratio of tall to short plants in the F2 generation supports the principle of Mendelian inheritance, specifically the principle of segregation. This principle states that during the formation of gametes, the two alleles responsible for a particular trait segregate from each other, so that each gamete carries only one allele.
To understand how this principle applies to the given scenario and how it leads to the 3:1 ratio, you need to start with the concept of dominant and recessive alleles. In this case, let's assume "T" represents the allele for tall plants and "t" represents the allele for short plants.
In the F1 generation (first filial generation), when a tall plant (TT) is crossed with a short plant (tt), all the offspring in the F1 generation are tall because the "T" allele is dominant over the "t" allele. So, all the plants in the F1 generation are heterozygous (Tt) for the trait.
Now, when you cross two plants from the F1 generation (Tt x Tt), each parent can pass on either the dominant "T" allele or the recessive "t" allele to their offspring. These possibilities can be represented in a Punnett square:
T t
T| TT | Tt |
t| Tt | tt |
In this Punnett square, you can see that there are four possible combinations of alleles in the offspring: TT, Tt, Tt, and tt. Out of these, three combinations (TT, Tt, and Tt) result in tall plants because the "T" allele is present. Only one combination (tt) results in a short plant because both alleles are "t".
This means that the ratio of tall plants to short plants in the F2 generation is 3:1, which supports Mendel's principle of segregation. By understanding the pattern of inheritance and applying Mendel's principles, you can explain and predict the observed ratios in the F2 generation.