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Table 1 Mendel's novel observations summarised. Mendel demonstrated that crossing parental plants bearing alternative forms (A) and (a) of any one of seven traits generated a F1 population of plants (not shown) all of which were hybrids (Aa). Each of these F1 hybrid plants displayed only one of the two alternative parental traits, defined as the dominating trait (A). When these F1 hybrid plants were allowed to self-fertilise, the ratio of dominant to recessive traits in the F2 population was always close to 3:1.

From: We still fail to account for Mendel's observations

Pairs of parental plants Their F2 progeny
Dominant traits (A) Recessive traits (a) Number of F2
plants examined
trait ratio in the
F2 population
Green pods Yellow pods 580 2.82:1
Axial flowers Terminal flowers 858 3.14:1
Red flowers White flowers 929 3.15:1
Long stems Short stems 1064 2.84:1
Inflated pods Constricted pods 1181 2.95:1
Round seeds Wrinkled seeds 7324 2.96:1
Yellow seeds Green seeds 8023 3.01:1