Which of the following is correct about x-linked characteristics?
a. more males then females are affected.
b. equal numbers of males and females are affected.
c. more females then males are affected.
d. males have two copies of the alleles for these characteristics.

Select the correct answer. which statement applies only to the axial skeleton, not the appendicular skeleton? a. it contains a pivot joint. b. it has muscles attached that work in pairs. c. it contains red bone marrow. d. it possesses fossa for bone articulation. e. it protects the heart and lungs.