(a(i))[1]
State one kind of blood cell that helps defend the body against disease.
(a(ii))[2]
State two ways in which blood cells protect the body against disease.
(b(i))[2]
Define what is meant by a sexually transmitted infection.
(b(ii))[2]
State why antibiotics are not suitable for treating HIV infections.
(b(iii))[3]
Explain ways in which the spread of STIs can be controlled.