In 1900 Bateson and his colleagues studied inheritance of comb shape in fowls. There are four types of combs in fowls: rose, pea, walnut and single. Bateson first performed a cross between rose and single. The Fx hens all had a rose comb, and on inbreeding gave rise to an F2 progeny of rose and [...]
A monohybrid cross between a red-flowered snapdragon (Antirrhinum majus) and a white flowered variety does not produce red or white flowered plants in Fl as expected from mendelism. Instead the flowers are pink, i.e. intermediate between the two parents. This is because neither red flower colour nor white is dominant, but each allele has its [...]
Mendel extended his observations to trihybrid crosses involving three pairs of contrasting characters. The characters he considered were: seed shape—smooth (S) vs. wrinkled (s); colour of cotyledons—yellow (Y) vs. green (y); and flower colour—violet (V) vs. white (u). The F1 hybrid produces 8 types of gametes. These on selfing have equal chances to combine with [...]
Dominant versus Recessive: When two pure breeding varieties are crossed, the parental character that expresses itself unchanged in the F1 generation hybrids is dominant: the one that does not appear in Fl but appears in F2 is called recessive. In the above cross three- fourths of the F2 progeny show the dominant character and one-fourth [...]
Mendel crossed varieties of edible peas which showed clearcut differences in morphological characters such as colour of flowers (red vs. white), shape of pod (inflated vs.constricted), colour of pod (green vs. yellow), texture of seed (round vs. wrinkled), colour ofcotyledons (yellow vs. green), flower position (axial vs. terminal) and height of plant (tall vs.dwarf). He [...]
