In tomato plants, leaf shape is determined by a single gene with two alleles. The allele for regular leaves is dominant over the allele for potato-type leaves.
A geneticist crossed homozygous regular-leaved tomato plants with homozygous potato-leaved tomato plants. All of the offspring (F1 generation) had regular leaves.
Use a genetic diagram to show the parent genotypes, the gametes formed, and the genotypes of the F1 offspring. Use L L\,L to represent the allele for regular leaves and l l\,l to represent the allele for potato-type leaves.
The geneticist then ensured that the F1 offspring plants could only self-pollinate. The seeds produced grew to give F2 plants with a 3:1 3 : 1\,3:1 phenotypic ratio of regular-leaved to potato-leaved plants. (i) Suggest how the geneticist could ensure that these tomato plants self-pollinated and were not cross-pollinated by other plants.
(ii) Give the genotypes of the F2 offspring obtained from the self-pollinated F1 plants.
What is meant by the term recessive allele?
Some phenotypes are controlled by codominant alleles. What is meant by the term codominant alleles?
