Which of the options, A to D, represents a secondary non-specific defence mechanism against pathogens?
The destruction of bacterial cell walls by lysozyme in tears
The trapping of inhaled microbes by mucus in the airways
The engulfment and digestion of pathogens by macrophages
The synthesis and secretion of antibodies by plasma cells
40 exam-style questions on OCR A A Level Biology Communicable diseases, disease prevention and the immune system. Each one has a worked solution and a mark scheme showing where the marks go.