A plant breeder crossed two plants, one with red flowers, and the other with white flowers. Red is dominant. Calculate the phenotype and genotype ratios of the F2 generation of this cross.

Is this a monohybrid or dihybrid cross?


closed as off-topic by Chris, rg255, Remi.b, Léo Léopold Hertz 준영, Ilan Apr 17 '14 at 16:17

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  • $\begingroup$ In the problem, is this simple dominance? In real life, isn't this trait incomplete dominance? $\endgroup$ – evamvid Apr 17 '14 at 2:07
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    $\begingroup$ I've voted to close because this question shows no effort to come up with an answer - this is not in one with the biology SE homework policy. $\endgroup$ – rg255 Apr 17 '14 at 11:28

Unfortunately, that isn't a very well-written problem, but I think I can help. If we assume simple Mendelian genetics, this would be a monohybrid cross, as you're only examining one trait (flower color).

You have a pure-breeding white flower and a pure-breeding red flower. These make up the P (parental) generation. Their offspring will be the F1 (first filial) generation. A cross of two plants from the F1 generation produces the F2 (second filial) generation.

Since each P-generation plant in the has only one possible allele to give, each of the F1 plants will inherit one red and one white allele. Because red is dominant, all F1 plants's phenotypes will be red.

When you cross two F1 plants, each has a 50% chance to pass on either the red or the white allele.

Using Punnett Squares: enter image description here


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