let\'s say you have 9 black mices, 19 black and white mices and and 14 white mic
ID: 12982 • Letter: L
Question
let's say you have 9 black mices, 19 black and white mices and and 14 white mices. black is dominant to white.1) what phenotypic ratio is observed setting the lowest number to one: black? white and black? white?
I answered: 2.1 Black/white : 1.5 White : 1 Black. is that correct?
2) what is the most likely genotype for each phenotype observed
I answered: B=black and b=white:
pure black BB
black/white Bb
pure white bb
3) you have 3 phenotypes present in these mice what genetic condition would result in this kind of segregation? ans: epistasis but I am not sure.
4) suppose you were given another box of mice but from a different set of parents. bases on te observed phenotypes what would be the most likely genotypes of the mouse parents for this micelings. 18 black and white mices and 15 white mices. I answered BB for white and Bb for white and black, but I am not sure.
Explanation / Answer
1) yes, 2.1 Black/white: 1.5 White: 1 Black is correct - except I would consider rounding 1.5555... up to 1.6. 2) Yes, since black is dominant it would be BB (making the other two genotypes obvious). 3) The 3 phenotypes could be caused by either codominance or incomplete dominance: incomplete dominance would result in a heterozygote (Bb) with neither phenotype fully expressed (neither black or white, but probably gray instead). Codominance would result in a heterozygote with the phenotypes for both alleles being expressed (like in this problem, the mice have black and white coats). So, I would contribute this to Codominance. 4) Since it is given that black is dominant, BB represents the black mice. The correct answer for this question is Bb for black and white and bb for white since all the micelings are Bb and bb. Example cross: Bb x bb --> Bb and bb in a 1:1 ratio 18 Bb and 15 bb is pretty close to a 1:1 ratio (since there is some expected variance from the ratio).
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