(a(i))[2]
State the names of the virus parts marked X and Y in Fig. 6.1.
(a(ii))[2]
State two differences between the structure of bacteria and the structure of viruses.
(b(i))[2]
State two ways in which a pathogen may be spread indirectly.
(b(ii))[2]
State two mechanical barriers of the body.
(c)[4]
Describe the role of antibodies in defence of the body.
(d)[3]
Explain how active immunity is different from passive immunity.