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neurologyYou need to know

• A pathogen is a microorganism or virus that causes infectious disease in a host.
• Pathogens can be spread by direct contact, contaminated food or water, droplets in the air, body fluids, and vectors such as insects.
• The human body has non-specific defences against pathogens, including skin as a physical barrier, blood clotting to seal wounds, mucus and cilia in the respiratory system, stomach acid, and antimicrobial secretions.
• Bacteria can make us ill by reproducing rapidly inside the body and producing toxins that damage tissues.
• Viruses can make us ill by entering host cells, reproducing inside them, and causing cell damage when new virus particles are released.
• The spread of communicable disease can be reduced by hygiene measures, isolation of infected individuals, destroying or controlling vectors, safe food preparation, clean water, barrier methods, and vaccination.
• White blood cells defend the body by phagocytosis, producing specific antibodies, and producing antitoxins that neutralise toxins.
• Antibodies are specific because their binding sites have a complementary shape to antigens on a particular pathogen.
• Vaccines contain dead, weakened, or harmless parts of a pathogen that stimulate lymphocytes to produce specific antibodies and memory cells without causing serious disease.
• The secondary immune response is quicker and stronger because memory lymphocytes recognise the antigen and rapidly produce large amounts of the correct antibody.
• Vaccinating a large proportion of a population reduces disease transmission because fewer people can become infected and pass on the pathogen, which is called herd immunity.
• Antibiotics treat bacterial infections by killing bacteria or stopping their growth, but they do not kill viruses.
• Antiviral drugs are difficult to develop because viruses reproduce inside host cells, so treatments must target the virus without damaging the body’s cells.
• Antibiotic resistance increases when random mutations produce resistant bacteria and antibiotic use creates selection pressure, allowing resistant bacteria to survive and reproduce.
• Digitalis was traditionally extracted from foxglove plants, aspirin was originally developed from compounds found in willow bark, and penicillin was discovered from the Penicillium mould.
• New medicines are developed through discovery, preclinical testing on cells, tissues and animals, and clinical trials on healthy volunteers and patients to test toxicity, efficacy and dose.
• A double-blind trial is a clinical trial in which neither the patients nor the doctors know who has received the drug or placebo, reducing bias in the results.
• Monoclonal antibodies are identical antibodies made from a single clone of hybridoma cells, formed by fusing a lymphocyte that makes the desired antibody with a tumour cell that divides rapidly.
• Plant diseases may be caused by pathogens or ion deficiencies, and they can be detected by symptoms such as stunted growth, spots on leaves, discolouration, malformation, and areas of decay.
• Health is a state of physical and mental well-being, and it can be affected by communicable diseases, non-communicable diseases, diet, stress, life situation and interaction between diseases.

• Compare transmission routes and prevention methods for bacterial, viral, fungal and protist diseases, using named examples and accurate terminology.
• Evaluate methods of reducing disease transmission by weighing effectiveness, practicality, cost, social impact and possible limitations.
• Explain immune responses in sequence, linking antigen recognition, antibody production, memory cells and the faster secondary response.
• Interpret vaccination data to judge the effect of herd immunity on infection rates across a population.
• Describe the production and uses of monoclonal antibodies, including their use in pregnancy tests, diagnosis, measuring substances, locating specific molecules, and targeted treatment.
• Use aseptic technique to investigate the effect of antiseptics on bacterial growth, including sterilising equipment, using controls, measuring inhibition zones and safely disposing of cultures.
• Identify possible plant diseases by matching visible symptoms to pathogens or ion deficiencies, then suggest appropriate confirmatory methods such as laboratory testing or using identification guides.
• Distinguish correlation from causation when analysing epidemiological data, explaining whether evidence supports a causal mechanism.
• Interpret graphs and tables about risk factors, cancer, and non-communicable disease by describing trends, comparing groups, and identifying limitations in the data.
• Evaluate the human and financial costs of non-communicable diseases at local, national and global scales using evidence such as healthcare costs, reduced quality of life and lost productivity.