What proportion of blue flowed progeny plants will breed true if self-fertilized?

Blue flowers are dominant to pink flowers. When a blue flower is self-pollinated, its progeny are 32 blue flowered plants %26amp; 9 pink plants. What proportion of the blue progeny plants will breed true if self-fertilized? Why/how?

What proportion of blue flowed progeny plants will breed true if self-fertilized?
The blue flower is heterozygous since it contains the alleles for blue and pink. Lets call the dominant allele, blue, B and pink, b.


So crossing Bb with itself Bb yields:


BB, Bb, Bb, bb





so about 3/4 should be blue and 1/4 pink. Our theoretical is similar to actual data.





Of the blue (BB, Bb, Bb) 2/3 if self fertilized will still yield pink.


But 1/3 (BB) will breed true blue!
Reply:Silly. Divide 32 by 9, that's your ratio.





That's how many blue flowers to pink flowers you'll have if you let your blue flowers breed.





If you were to look at the problem as a box, you would see that the answer should be about 4 to 1:





this is why:





BB Bp


Bp pp = where B is the dominant blue flower, and p the recessive trait to be a pink flower.





We cross multiply them, like fractions. We get


BB Bp - blue flower


BB Bp - blue flower


BB Bp - blue flower


BB pp - pink flower.





B is "true" as BB Bp, a blue flower with no pink gene.


BB Bp will show as a blue flower, but has a "carrier" for a pink flower. When breeding BB, you will get either Bp or pp or BB. Most frequently you will get BB, but those recessive genes show up. About one flower in four will be the recessive pink combination.





Of course you just learned nothing. What's the point of homework again?