question archive Hello there, Would you please help me with this question
Hello there, Would you please help me with this question
Subject:BiologyPrice:2.84 Bought3
Hello there,
Would you please help me with this question. Thank you so much!
Loplins have horns, with wild type horns being a conical shape. Horn shape is determined by one gene - Horn. The Horn gene is located on the X chromosome and male loplins have XY chromosomes and female loplins have XX chromosomes. There is a gain-of-function mutation of Horn which causes a branched horn. The wild-type phenotype (conical shape; H) is dominant to the branched horn phenotype (h).
You cross individuals from two true-breeding lines: a yellow eyed female with a branched horn to a white eyed male with a wild type horn. You then intercross the F1s (cross the F1s to each other). Of the 270 offspring (F2) produced how many do you expect would have wild type eyes and mutant (branched) horns? Assume all genes sort independently.
Note: only whole numbers of offspring are possible (can't have a fraction of a child) so there may have been some rounding.
Select one:
a. 38 with more males having branched horns than females.
b. 76 with equal numbers of males and females having branched horns.
c. 51 with more males having branched horns than females.
d. 110 with equal numbers of males and females having branched horns.
e. 76 with more males having branched horns than females.
f. 51 with equal numbers of males and females having branched horns.
g. 110 with more males having branched horns than females.
h. 38 with equal numbers of males and females having branched horns.
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Since the F1 is produced from true breeding lines, the genotype of parental generations are: (w for yellow eye and W for white eye)
(female) wwXhXh x WWXHY (male)
For the F1 generations, all of them will have Ww alleles. Females will have XHXh whereas males will have XhY.
By intercrossing the F1 generations, their offspring will have the following eye gene in the following ratio:
WW : Ww: ww = 1 : 2 : 1
Their offspring (F2) will have the following horn gene in the following ratio:
XHXh : XhXh : XHY : XhY = 1:1:1:1
Since the two genes are independent to each other, number of F2 individuals having wild type eye = 3/4 (270) = 203
Of the 203 individuals, 2/4 of them have branched horns
Individuals with branched horns = 203 (2/4) = 102
The genotype of branched horns are XhXh and XhY, the male to female ratio is 1:1
Therefore the best answer should be d. 110 with equal numbers of males and females having branched horns.
