In response to pathogen invasion, plants synthesize and deposit the polysaccharide callose at plasmodesmata, between the cell wall and plasma membrane of infected cells, and within sieve tubes.
Which of the following describes the primary mechanism by which callose maintains plant health?
It acts as a physical barrier to prevent the symplastic and systemic transport of the pathogen.
It functions as a chemical defence by enzymatically degrading the pathogen's cell wall.
It acts as an antigen-presenting molecule to recruit plant immune cells to the site of infection.
It is released into the vascular system to act as an opsonin, marking pathogens for phagocytosis.
97 exam-style questions on OCR GCSE Biology 6.3 Monitoring and maintaining health, covering 6.3.1 Health and disease, 6.3.2 Interactions between diseases, 6.3.3 Spread of communicable diseases, 6.3.4 Common infections and diseases, 6.3.5 Physical plant defence responses, 6.3.6 Chemical plant defence responses, 6.3.7 Detecting and identifying plant diseases, 6.3.8 White blood cells and platelets, 6.3.9 Non-specific defence systems, 6.3.10 The immune system, 6.3.11 Monoclonal antibodies, 6.3.12 Vaccines and medicines, 6.3.13 Aseptic techniques, 6.3.14 Discovery and development of new medicines, 6.3.15 Causes of non-communicable diseases, 6.3.16 Treatments for cardiovascular disease, 6.3.17 Lifestyle factors and non-communicable diseases, 6.3.18 Cancer, 6.3.19 Stem cells in medicine, 6.3.20 Gene technology in medicine, and 6.3.21 The human genome and medicine. Each one has a worked solution and a mark scheme showing where the marks go.