Question 2 Not yet answered Points out of 25.00 Not flaggedFlag question Question text Human genetic disorders are not usually evenly distributed among all rac

Question

Human genetic disorders are not usually evenly distributed among all racial and cultural groups due to the different genetic histories of the world's people. One example of such a recessive inherited disorder is cystic fibrosis.
Cystic fibrosis
The most common lethal genetic disease in the United States, strikes 1 in every 2,500 Caucasians (it is much rarer in other races).
Four percent of the Caucasian population are carriers.
The dominant allele codes for a membrane protein that controls chloride traffic across the cell membrane. Chloride channels are defective or absent in individuals that are homozygous recessive for the cystic fibrosis allele.
Disease symptoms result from the accumulation of thickened mucus in the pancreas and lungs.
Statistics from: http://iws.collin.edu/biopage/faculty/mcculloch/1406/outlines/chapter%2013/chap13.html
Use a Punnett square to predict the results of a monohybrid cross and state the phenotypic and genotypic ratios of the offspring (F2 generation). F= dominant cystic fibrosis allele, f = recessive cystic fibrosis allele
a. Punnett square:


b. The phenotypic ratio (no CF : yes CF) is
a. 2:2
b. 1:3
c. 1:1
d. 3:1

c. The genotypic ratio (homozygous dominant for CF : heterozygous for CF : recessive for CF) is
a. 2:1:1
b. 3:1:0
c. 1:2:1
d. 0:2:2

Answer 1

F | f

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F | FF | Ff

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f | Ff | ff

FF = no CF

Ff = carrier, no CF

ff = has CF

Phenotypic ratio = 3:1

Genotypic ratio = 1:2:1