An inbred strain of plants has a mean height of 24 cm. A second strain of the same species from a different geographical region also has a mean height of 24 cm. When plants from the two strains are crossed together, the Fl plants are the height as the parent plants. However, the F2 generation shows a wide range of heights: the majority are like the P1 and Fl plants, but approximately 4 of 1000 are only 12 cm high, and about 4 of 1000 are 36 cm high.

(a) What mode of inheritance is occurring here?

(b) How many gene pairs are involved?

(c) How much does each gene contribute to plant height?

(d) Indicate one possible set of genotypes for the original P1 parents and the Fl plants that could account for these results.

(e) Indicate three possible genotypes that could account for F2 plants that are 18 cm high and three that account for F2 plants that are 33 cm high.

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a One of the parent is 12 cm high and the other is 36 cm high Therefore the mean height is 24 cm In this cross the F1 plants also have a mean height o... View the full answer