Answer:
1:2:1
Step-by-step explanation:
If two alleles of a gene are incompletely dominant then selfing between two individuals which are heterozygous for these alleles will produce phenotypic ratio as 1:2:1. In such cases phenotypic and genotypic, both the ratios are same.
For example, if two alleles T1 (dominant) and T2 (recessive) represent a flower color in which homozygous dominant alleles produce red colored flower, heterzogygous alleles produce pink flower and homozygous recessive alleles produce white colored flower then selfing between heterzogygous plants will produce three type of flower colors which are red (T1T1), pink (T1T2) and white (T2T2) in the ratio 1:2:1.
The cross is depicted as under:
Parental T1T2 x T1T2
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Progeny T1T1 T1T2 T1T2 T2T2
Here, genotypic ratio is also 1:2:1
Such inheritance is known as incomplete inheritance or blended inheritance.