Down syndrome can occur: a. as a result of translocation during mitosis. b. most frequently in the offspring of men under the age of 40. c. most frequently in the offspring of women under the age of 40. d. because of nondisjunction, which yields an extra chromosome.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.

a chain link fence because there so tiny even my albino donkey can't get out