What is the first step in producing a vaccine against an infectious disease? A inactivating the disease agent
B testing for vaccine side effects
C finding and isolating the disease agent
D isolating antigens

Red blood cells are responsible for transporting oxygen in the blood. people with sickle cell anemia were born with a defective gene that results in sickle-shaped red blood cells. individuals with the disease often suffer pain in their extremities due to the build-up of these cells causing blockages in the blood vessels. the shape of the blood cells also reduces the amount of oxygen transported in the blood.