Cystic fibrosis is a recessive gene disorder. The pedigree chart for a family known to have cystic fibrosis is shown below. What percentage of the offspring neither have the disease nor are carriers for the disease?
0%
25%
50%
75%

thrombocytopenia, which is a deficiency in blood platelets, can cause bleeding and bruising in the dermis similar to senile purpura. other possible causes include: exposure to ultraviolet rays and aging skin are common causes of senile purpura. senile purpura may also be a sign of collagen loss in the skin and bones.