Problem 1: Tongue Rolling
Tongue Rolling
Problem 2: Eye Colour
Eye Colour
Problem 3: Diabetes
Problem 4: Blood Type
Blood Type

Diabetes is a disorder of the pancreas in which insulin cannot be produced or is not effective. As a result, blood sugar cannot be properly controlled.

Diabetics have a homozygous recessive genotype (dd).

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A father carries the recessive gene for diabetes and a mother does not (generation 1). They have two children (generation 2), a daughter and a son. The daughter does not suffer from diabetes and marries a man who does not carry the gene for diabetes. They have one child, a girl who is a carrier (generation 3). The son marries a diabetic woman and they have two boys, both who suffer from diabetes (generation 3).

homozygous dominant male

heterozygous/carrier male

homozygous recessive male

homozygous dominant female

heterozygous/carrier female

homozygous recessive female

homozygous dominant genotype
heterozygous/carrier genotype
homozygous recessive genotype
  1. Can the parents in generation 1 produce a child with diabetes?


  2. How many individuals in the entire generation 2 suffer from diabetes (1, 2, 3 or 4)?


  3. If you only knew that the girl in generation 3 didn't suffer from diabetes, what is the best way to write her genotype?


  4. What genotype must the boys in generation 3 marry so their children do not suffer from diabetes?


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© Copyright 2008, E. Kimmel