In rabbits, noses can be pink or black and the fur can be either white or spotte
ID: 273175 • Letter: I
Question
In rabbits, noses can be pink or black and the fur can be either white or spotted. In a field of clovers, two rabbits of unspecified phenotypes met and the following progeny is obtained in the course of a summer:
Pink nose and white fur 25
Pink nose and spotted fur 7
Black nose and white fur 22
Black nose and spotted fur 9
A. Identify the ratio for the 4 phenotypic classes in the progeny. And state your hypothesis
B. What would be the expected number of rabbits with black nose and white fur?
C. What are the degrees of freedom?
D.If the total chi square value is 8.2, which decision would you make on your hypothesis? Species.
Explanation / Answer
A. Identify the ratio for the 4 phenotypic classes in the progeny. And state your hypothesis.
The ratio of phenotypic classes here is 3:1:3:1. As this ratio is not equal to 9:3:3:1 (dihyrbid F2 ratio) and 1:1:1:1 (dihyrbid testcross ratio) which means those genes are linked.
B. What would be the expected number of rabbits with black nose and white fur?
As the data is showing results of linked genes, the proportion of black nose and white fur is 1/4, so the expected number is = 63*1/4 = 15.72 ~ 16.
C. What are the degrees of freedom?
The formula is = number of phenotypic classes - 1; so here the answer is 4-1 = 3
D. If the total chi square value is 8.2, which decision would you make on your hypothesis?
Null hypothesis: The observed values are not deviating from the expected values.
Chisquare test:
Category
Pink nose and white fur
Pink nose and spotted fur
Black nose and white fur
Black nose and spotted fur
Total
Observed values (O)
25
7
22
9
63
Exptected Ratio (ER)
1
1
1
1
4
Exprected Values (E)
15.75
15.75
15.75
15.75
Deviation (O-E)
9.25
-8.75
6.25
-6.75
D^2
85.5625
76.5625
39.0625
45.5625
D^2/E
5.43254
4.861111
2.480159
2.892857
15.66667
X^2
15.66667
Degrees of freedom
4
-
1
3
Inference: The calculated chisquare value i.e. 15.66 is greater than the provided chisquare in the problem i.e. 8.2, hence the null hypothesis is rejected.
Category
Pink nose and white fur
Pink nose and spotted fur
Black nose and white fur
Black nose and spotted fur
Total
Observed values (O)
25
7
22
9
63
Exptected Ratio (ER)
1
1
1
1
4
Exprected Values (E)
15.75
15.75
15.75
15.75
Deviation (O-E)
9.25
-8.75
6.25
-6.75
D^2
85.5625
76.5625
39.0625
45.5625
D^2/E
5.43254
4.861111
2.480159
2.892857
15.66667
X^2
15.66667
Degrees of freedom
4
-
1
3
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.