let
us look at the given picture.
(a) The sinistral female egg is the mother and the genotype of the left coiling mother is SS that is sinistral homozygous. as mother's genotypes govern offspring's phenotype.
(b) The genotype of the offspring will be SS* heterozygous because the progeny is right coiling.
(c) the genotype of right coiling snail must be SS* upon self-fertilization it must give 2 SS, SS* and 1 S*S*
so the frequrncy will be 3:1
4. A snail whose shell coils to the left undergoes self-fertilization. All the progeny have shells...
Maternal effect genes are a special class of genes that have their effect in the reproductive organs of the mutant. They are interesting because the mutant organism may appear phenotypically normal, and it is the progeny that express detectable differences, and they do so whether the progeny have inherited the mutant gene or not. The first maternal effect gene identified was the gene controlling shell coiling in the water snail Lymnaea peregra. Alleles of this maternal effect gene are non-lethal...