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| Question | Answer |
| How are infectious diseases caused? | Infectious diseases are caused by pathogens. Pathogens are microorganisms that cause disease. |
| State the 4 types of pathogens and give an example of what they can cause. | fungi - athlete's foot bacteria - cholera viruses - flu protozoa (single-celled organisms) - dysentery |
| How are the symptoms of an infectious disease caused? | The symptoms of an infectious disease are caused by cell damage or by toxins produced by pathogens. |
| What are non-infectious diseases? | Diseases that are not caused by pathogens. |
| Give 3 examples of non-infectious diseases and what causes them. | Scurvy is caused by vitamin C deficiency Anaemia is caused by iron deficiency Diabetes and cancer are disorders of the body. |
| Give an example of a genetically inherited disorder. | Red-green colour vision deficiency. |
| Explain how malaria spreads throughout populations. | Malaria is caused by a protozoan (parasite) and carried by the mosquitoes (vectors). They pick up the malaria parasite when they feed on an infected animal. When the mosquito feeds on another animal it infects it by inserting the parasite into the animal's blood vessels. |
| Give 3 ways to reduce the spread of malaria. | Drain or spray the areas of water, that mosquitoes lay eggs in, with insecticides. Fish can be introduced to eat mosquito larvae People can be protected from mosquitoes using insecticides and mosquito nets. |
| How does the human body defend itself against pathogens? | Skin provides a barrier Blood clotting prevents entry of pathogens Pathogens are trapped by mucus Hydrochloric acid in the stomach kills pathogens. |
| How does the immune system deals with pathogens? | Consuming - White blood cells engulf foreign cells and digest them. Producing Antitoxins - Antitoxins counter the effect of any toxins produced by pathogens. Producing Antibodies - White blood cells produce antibodies, which lock on to the antigens and kill the invading cells. |
| What are memory cells? | The white blood cells stay in the blood after the pathogen has been fought off - these are called memory cells. If the person is infected with the same pathogen again these cells will remember it and immediately make antibodies to kill it. |
| What is immunisation? | Immunisation involves injecting dead or inactive pathogens into the body. These carry antigens, and will trigger an immune response. Memory cells will remain so antibodies to kill the same pathogen will be produced immediately. |
| What immunity is immunisation classed as? | Immunisation is classed as active immunity. |
| Explain the different types of immunity. | Active immunity is where the immune system makes its own antibodies after being stimulated by a pathogen. Passive immunity is where you use antibodies made by another organism, Passive immunity is only temporary. |
| Give 2 advantages of immunisation. | Immunisation stops you from getting ill. If most people are immunised the disease won't be able to spread as easily. |
| Give 2 disadvantages of immunisation. | There can be short-term side effects, eg. swelling and redness and feeling unwell Can't have some vaccines if your immune system is weakened. |
| What are antibiotics? | Antibiotics are drugs that kill bacteria without killing your own body cells. They're very useful for clearing up bacterial infections that the body can't handle, however they don't kill viruses. |
| What are antivirals? | Antivirals can be used to treat viral infections. Antivirals are drugs that stop viruses from reproducing. |
| What are resistant bacteria? | A bunch of bacteria, including a resistant variety get bathed in antibiotics. Most of the normal bacteria die. The resistant bacteria multiply and become more common. Eventually, the entire infection evolves into a resistant strain. |
| Explain the 3 stages of drug development. | 1. The drugs are tested using computer models and human cells. 2. Drugs are tested on animals. A typical test involves monitoring animals for any side-effects. 3. Drugs are used in clinical trials. They are tested on healthy volunteers to check that they are safe. |
| Explain why drug development is so expensive and takes a long time. | Most substances do not pass all of the tests and trials, so drug development is expensive and takes a long time. |
| What is a blind trial? | Blind trials aim to minimise the 'placebo effect'. They do this by designing a placebo that looks like the drug. Some patients are given the drug while others are given a placebo. The patients are not told who have received the drug or the placebo until the trial is over. |
| What is a double blind trial? | It is exactly the same as a blind trial except both the doctors and the patients do not know who have received the placebo or drug. |
| What is cancer? | A cancer happens when cells begin to divide out of control - forming tumours. |
| Explain the 2 types of tumours. | Benign tumours grow slowly and are usually harmless. Malignant tumours often grow more quickly and may spread throughout the body. They can be fatal. |
| How does diet and lifestyle affect the risk of developing cancer? | Smoking increases the risk of lung cancer Using sunscreen reduces the risk of skin cancer Eating more fruit and vegetables reduces the risk of bowel cancer. |
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