In some plants, the red pigment cyanidin is synthesized from a colorless precurs
ID: 206301 • Letter: I
Question
In some plants, the red pigment cyanidin is synthesized from a colorless precursor. Cyanidin can then be converted to the purple pigment violicin by addition of a methyl group.
Product of Gene A Product of Gene B
Colorless ------------------------> Cyanidin ------------------------> Violicin
Precursor
In a cross of two randomly selected purple plants, the following F1 progeny were obtained:
92 purple-flowered 31 red-flowered 42 white-flowered
Note that this ratio is close to a 9/16 : 3/16 : 4/16, confirming that two genes must be involved in determining flower color. Based on this 9:3:4 ratio in the progeny, what do the genotypes of the purple parents have to be?
A) Draw a punnett square showing the genotypes and phenotypes of the F1 progeny to show how they created that 9:3:4 ratio.
- Having a lot of trouble with punnett square
Explanation / Answer
Answer:
B_A_ = Purple
B_aa= Red
bbA_ or bbaa = White
BbAa (purple) x BbAa (purple)-----Parents
BA
Ba
bA
ba
BA
BBAA (purple)
BBAa (purple)
BaAA (purple)
BbAa (purple)
Ba
BBAa (purple)
BBaa (Red)
BbAa (purple)
Bbaa (Red)
bA
BbAA (purple)
BbAa (purple)
bbAA (white)
bbAa (white)
ba
BbAa (purple)
Bbaa (Red)
bbAa (white)
bbaa (white)
Purple = B_A_ = 9/16
Red = B_aa= 3/16
White = bbA_ or bbaa = 4/16
BA
Ba
bA
ba
BA
BBAA (purple)
BBAa (purple)
BaAA (purple)
BbAa (purple)
Ba
BBAa (purple)
BBaa (Red)
BbAa (purple)
Bbaa (Red)
bA
BbAA (purple)
BbAa (purple)
bbAA (white)
bbAa (white)
ba
BbAa (purple)
Bbaa (Red)
bbAa (white)
bbaa (white)
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