(i) Colour blindness is an X-linked inheritence. Women have two Xchromosomes. so even when one X-chromosome carry colour blindness, the other X-chromosome over comes the abnormal trait Whereas men have only one Xchromosome. So when it is affected the man becomes a colour blindness. 

(ii) Medulla oblongata controls the involuntary activities like respiration, heart beats etc. So any injury to this part of brain arrests these movements and cause death. 

(iii) Menstrual cycle occurs due to rupture and shedding oi the endometrium lining of the uterus. When an ovum gets fertilised the endometrium gets thickned, and vascularized to house the embryo. So during the whole term when the embryo/foetus is in the uterus, menstrual cycle stops temporarily. 

(iv) Presence of nucleus would occupy space and reduce the oxygen carrying capacity. Nucleus is also not required as a mature RBC does not divide. Mitochrondria is absent so that oxygen is not consumed by the RBC and all the oxygen is transported to target areas. 

(v) Arteries carry blood from heart. With every pump of heart blood flows with a jerk and pressure through it.