Huntington disease and cystic fibrosis are examples of single-gene defects. Individuals who have disorders due to single-gene defects:
a. have one or more complete chromosomes with irregular structures.
b. usually have an error in both genes in the allele pair.
c. usually have an error in one of their dominant genes.
d. have two recessive genes and no dominant gene.
Question 2
Some physical disabilities are the result of genetic abnormalities. An example is Down syndrome, in which:
a. Children have a defective dominant gene
b. Children have a defective recessive gene
c. Children have an extra chromosome
d. Children are missing a chromosome