Question

Radix peregra is a species of air-breathing freshwater snail. The direction in which the shell coils can be dextral  (righthand) or sinistral (left-hand). The maternal genotype determines will follow shell coil pattern the progeny will have, regardless of the zygote's genotype. If the maternal genotype has the dominant genes s+, all the progeny will coil dextrally; if the maternal genotype is ss, all the progeny will coil sinistrally. This coiling pattern persists for the life of the snail.

Radix peregra is a hermaphroditic snail that can reproduce either by crossing or by self-fertilization.

Question: A Raddy the snail (Radix peregra)has a sinistral shell. Raddy produces progeny by self-fertilization and they are all dextral shelled. Raddy was the product of a cross-fertilization.  Draw a pedigree with Raddy, Raddy's parents, and one of Raddy's progeny. Include as much genotype information as you can

Answer 1

Ans- Mother's genotype- ss

Mother's phenotye- sinistral shell

  Father's genotype- S+

Father's genotype -dextral shell

Raddy's genotype- s+

Raddy's phenotype - sinistral shell (beacause mother of raddy is sinistral.The maternal genotype determines will follow shell coil pattern the progeny will have, regardless of the zygote's genotype)

On self fertilization Raddy will have offspering-

Parent's gamete s+s+ x s+ s+

Gametes- s+,  s+

Self fertilization- s+ x s+

Genotype of offspring's- s+s+

Phenotype of offspring's- dextral shell