Download H2 HomeFun Worksheet -Teacher`s Copy - CIA-Biology

Grade 11 Biology
Unit: Genetic Processes
Name: ____Answer Key______
Date: _____________________
Answer Key: Home Fun: Genetic Problems relating to Human Conditions H2
1. In humans, the gene causing diabetes is recessive to the normal gene. What
would be the genotypes and phenotypes for the following individuals?
a) children of a normal man and a diabetic woman?
b) the children of two diabetics
c) the children of two normal people one of whom is a carrier
d) the children of two normal people both of whom are carriers
Hint: Let N be the allele for the normal gene and let n be the allele for the diabetic gene.
a) Normal man = NN; Diabetic woman = nn
N
N
Genotype of Children: Phenotype of Children:
n
Nn
Nn
n
Nn
Nn
100% Nn
100% carriers
All their children will be carriers
b) Both parents = nn
n
n
Genotype of Children: Phenotype of Children:
n
nn
nn
n
nn
nn
100% nn
100% diabetic
All their children will be diabetic.
c) Normal parent = NN; Carrier parent = Nn
N
N
Genotype of Children: Phenotype of Children:
N
NN
NN
n
Nn
Nn
50% NN
50% Nn
50% normal
50% carrier
Half of their children are predicted to be normal and the other half are predicted to be carriers.
d) Both parents = Nn
N
n
Genotype of Children: Phenotype of Children:
N
NN
Nn
n
Nn
nn
25% NN
50% Nn
25% nn
25% normal
50% carriers
25% diabetic
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Grade 11 Biology
Unit: Genetic Processes
Name: ____Answer Key______
Date: _____________________
There is 25% chance that their children will be normal, 50% chance that their children will be
carriers and 25% chance that their children will be diabetic.
Answer Key Home Fun: Genetic Problems relating to Human Conditions H2
2. Brachydactyly is an inherited trait where the fingers and toes are short. This trait
is dominant trait to the normal condition. A heterozygous brachydactylous man
marries a normal woman. What is the chance that:
a) their first child will be brachydactylous?
b) all their three children will be brachydactylous?
c) none of their three children will be brachydactylous?
Let B represent the allele for the Brachydactyly trait.
Let b represent the allele for the normal trait.
Man= Bb; woman bb
B
b
Genotype of Children: Phenotype of Children:
b
Bb
bb
b
Bb
bb
50% Bb
50% bb
50% brachydactylous
50% normal
a) There is 50% chance that their first child will be bachydactylous.
b) There is 50% chance that all three children will be brachydactylous.
c) There is 50% chance that all three children will inherit the normal gene
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