A genetic disease can be expressed in the offspring when
1) both parents had a recessive gene for that disease.
2) both parents had a dominant gene for that disease.
3) only one parent had a dominant gene for that disease.
4) only one parent had a recessive gene for that disease.

Question

A genetic disease can be expressed in the offspring when
 1) both parents had a recessive gene for that disease.
2) both parents had a dominant gene for that disease.
3) only one parent had a dominant gene for that disease.
4) only one parent had a recessive gene for that disease.

Quizplus · Accepted Answer

A genetic disease can be expressed in the offspring if both parents carry a recessive gene for that disease (1), both parents have a dominant gene for that disease (2), or if only one parent carries a dominant gene for that disease (3). Recessive diseases require two copies of the gene (one from each parent) to be expressed, while a dominant disease can be expressed with just one copy of the gene from either parent.

A Genetic Disease Can Be Expressed in the Offspring When