AQA Infection and response Knowledge organiser

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controlled be antiviral drugs; this stops the viruses replicating. The virus attacks the cells in the immune system. If the immune system is badly damaged, the body cannot cope with other infections. This is the late stage and is called Aids. Tobacco mosaic virus affects plants. Parts of the leaves become discoloured. This means plants cannot carry out photosynthesis; this will affect the plants growth. Fungal and Protist Diseases Fungal Rose black spot shows as black spots on the leaves of the plant. This means less photosynthesis occurs. As a result, the plant does not grow as well. It is spread by the wind or the water. They can be treated by using fungicides and taking the leaves off the infected plant. Protists Malaria is caused by a protist; mosquitoes are the vectors. They become infected when they feed on an infected animal. The protist is inserted into the blood vessel. Malaria can cause fever and it can also be fatal. Page 1 of 3 Bacterial Diseases Salmonella bacteria causes food poisoning. Symptoms include fever, stomach cramps, vomiting and diarrhoea. The symptoms are caused by the toxins produced by the bacteria. Food contaminated with salmonella can give you food poisoning. Most poultry in the UK will have had a vaccination against salmonella. Gonorrhoea is a sexually transmitted bacterial disease, passed on by sexual contact. Symptoms include pain when urinating and thick yellow/green discharge from the vagina or penis. To prevent the spread, people should be treated with antibiotics and use a condom. How to prevent the spread: Being hygienic - washing hands thoroughly. Destroying vectors - killing vectors by using insecticides or destroying their habitat. Isolation - isolating an infected person will prevent the spread. Vaccination - people cannot develop the infection and then pass it on. visit twinkl.com twinkl AQA Infection and Response Knowledge Organiser Plant Diseases and Defences Plants need ions from the soil. If there isn't enough, then the plants suffer deficiency symptoms. Ion nitrates magnesium Symptoms stunted growth yellow leaves Plant Diseases common signs include stunted growth, spots on the leaves, patches of decay, abnormal growth, malformed stems or leaves and discolouration. Plants have physical, chemical and mechanical defences to stop pathogens. Physical waxy cuticle, cell walls, layer of dead cells. Mechanical - thorns, hairs, leaves that droop or curl and some plants can mimic other organisms. Fighting Diseases Defence System 1. The skin acts as a barrier to pathogens. 2. 3. 4. Hairs and mucus in your nose trap particles. The trachea and bronchi secrete mucus to trap pathogens. They also have cilia which move backwards and forwards to transport the mucus towards the throat. This traps any pathogens and the mucus is usually swallowed. The stomach contains hydrochloric acid to kill any pathogens that enter the body via the mouth. Secondary The Immune System This kills any pathogens that enter the body. White blood cells: 0 Phagocytosis is when white blood cells engulf pathogens and then digest them. They produce antitoxins to neutralise the toxins. They also produce antibodies. Pathogens have antigens on their surface. Antibodies produced by the white blood cells lock on to the antigen on the outside of the pathogen. White blood cells can then destroy the pathogens. Antibodies are specific to one antigen and will only work on that pathogen. Vaccinations Vaccinations have been developed to protect us from future infections. A vaccination involves an injection of a dead or weakened version of the pathogen. They carry antigens which cause your body to produce antibodies which will attack the pathogen. If you are infected again, the white blood cells can produce antibodies quickly. Pros Helps to control communicable diseases that used to be very common. Epidemics can be prevented. Cons They don't always work. Some people can have a bad reaction to a vaccine however, that is very rare. Page 2 of 3 Fighting Disease - Drugs Painkillers relive the pain and symptoms, but do not tackle the cause. Antibiotics kill the bacteria. causing the problem, but do not work on viruses. Viruses are very difficult to kill because they live inside the body cells. Developing Drugs There are three main stages in drug testing: Pre-clinical testing: 1. Drugs are tested on human cells and tissues. 2. Testing carried out on living animals. Clinical testing: 3. Tested on healthy human volunteers in clinical trials. Starts with a very low dose, then tested on people with the illness to find the optimum dose. Placebo is a substance that is like the drug but does not do anything. Placebo effect is when the patient thinks the treatment will work even though their treatment isn't doing anything. Blind trial is when the patient does not know whether they are getting the drug or the placebo. Double-blind trial is when both the doctor and the patient do not know whether they are getting the drug. visit twinkl.com twinkl AQA Infection and Response Knowledge Organiser Drugs from Plants Chemicals produced by plants to defend themselves can be used to treat human diseases or help with symptoms. aspirin digitalis Drug penicillin Key Vocabulary antibodies antigens antitoxins bacteria blind trial double-blind fungus Plant/Microorganism mould penicillium New drugs are now made by chemists, who work for the pharmaceutical industry, in laboratories. willow foxglove Secondary microorganism phagocytosis placebo protist toxins vaccination vector virus Monoclonal Antibodies Monoclonal antibodies are identical antibodies. Antibodies are produced by B lymphocytes. It is possible to fuse a B lymphocyte from a mouse with a tumour cell to create a cell called a hybridoma - these can be cloned. They will all produce the same antibodies; the antibodies can be collected and purified. antigen immunization C isolate immune cells $$ clonal monoclonal expansion antibodies antibody- forming cells antibody-producing hydromas cloned tumor cells fusion hybridomas Page 3 of 3 hybridomas screened for production of desired antibody There are many uses of monoclonal antibodies. For example: Pregnancy testing: HCG hormone is found in the urine of women when pregnant. Pregnancy testing sticks detect this hormone. The HGC binds to the antibodies on the stick and changes the colour if you are pregnant. If the woman is not pregnant, there is no HCG. This means there is nothing to stick to the blue beads on the test strip, so it does not go blue. Treating diseases: anti-cancer drugs can be attached to monoclonal antibodies. They can target specific cells (cancer cells) by binding to the cancer marker. This kills the cancer cells, but not the normal body cells. Research to find specific substances: used to bind to hormones and chemicals in the blood to measure levels. Also used in blood tests for pathogens and locating molecules on a cell or in tissue. Problems: they have more side-effects than originally thought. For example: fever, vomiting, low blood pressure. They are not used by doctors as much as was first thought. visit twinkl.com twinkl Approved