Description: S2.1 Genetically selected barley seeds.
Natural barley seeds carry a gene for the expression of the green plant pigment, chlorophyll.
This gene has alternate alleles:
A: Pigment produced - green. (dominant)
a: No pigment - albino (or white). (recessive) where pigment production is dominant to albino.
The seed provided has been obtained as a result of crossing plants heterozygous for the gene concerned.
For example: Aa x Aa
Genotype of seed: AA: 2Aa : aa
When the seeds germinate, plants that are AA will be green, Aa plants will also be green, and aa plants
will be albino. So when the seeds provided are germinated, we would expect the plants obtained to
approximate a 3 green : 1white ratio. White (albino) plants lack chlorophyll and will die as young seedlings because they are unable to photosynthesize.
Ideal as a practical way of demonstrating genetic inheritance, and for explaining why organisms with weaker traits are not programmed for survival.