In humans, the condition for normal blood clotting dominates the condition for non- clotting (hemophilia). these genes are sex-linked. if a male hemophiliac marries a woman who is a carrier for this trait, what are the chances that a male child will be normal for blood clotting? show work for credit!

Tlymphocytes mature in the? a. thyroid gland. b. bone marrow. c. spleen. d. thymus.

The table shows dates and appearance of index fossils. which rock layers can be dated most precisely? a) a layer containing both a fossil 4 and a fossil 3 b) a layer containing both a fossil 2 and a fossil 3 c) a layer containing both a fossil 1 and a fossil 4 d) a layer containing both a fossil 1 and a fossil 2

Aperson with age is more likely to catch diseases that healthy people usually don’t catch.what are these infections called?