Cystic fibrosis is a fatal lung condition that results from a recessive gene. If one parent is a healthy carrier for the condition while the other is not a carrier, what is the likely outcome for any children they might have?
a. The children will be heterozygous for cystic fibrosis, and all will develop the disease.
b. Fifty percent of their children will develop the disease, and the other fifty percent will be carriers.
c. None of the children will have the disease, and none will be carriers.
d. None of the children will have the disease, but they have a fifty percent chance of becoming carriers.
Question 2
Sarah's mother has Huntington's disease, an illness that results from a dominant gene. Her father, on the other hand, does not have the illness. What is the likelihood that Sarah herself will develop the disease?
a. Sarah has no chance of developing the disease, as she would have inherited a healthy allele from her father.
b. Sarah probably has a 50 percent chance of developing the disease, as her mother could have given her either a healthy allele or an allele that produces the illness.
c. Sarah has a 50 percent chance of developing the disease, because her mother would not have the disease herself unless she was homozygous for Huntington's disease.
d. Sarah has a 25 percent chance of developing the disease, because her father could be a carrier.
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