3 - Infection and Response

• Antibiotics are medicines that help to cure bacterial disease by killing infective bacteria inside the body.
• Clinical drug testing is drug testing done on healthy human volunteers and patients.
• Communicable disease is a disease that can be spread between individuals either directly or indirectly.
• Double blind trial is a study performed where neither the researcher or patient know whether the patient is taking the drug or a placebo.
• Gonorrhoea is a sexually transmitted disease (STD) caused by a bacterium with symptoms of a thick yellow or green discharge from the vagina or penis and pain on urinating.
• Human Immunodeficiency Virus (HIV) is an infectious virus that weakens the immune system and can lead to AIDS (acquired immunodeficiency syndrome).
• Malaria is a disease caused by a protist that causes recurrent episodes of fever and can be fatal.
• Measles is a serious disease caused by a virus that shows symptoms of fever and a red skin rash.
• Monoclonal antibodies are antibodies produced from a single clone of cells that are specific to one binding site on one protein antigen.
• Non-communicable disease is a disease which cannot be spread between individuals.
• Side effects: Other additional effects that the drug has that are different from the expected effect of the drug
• Rose black spot: A fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early
• White blood cell: An important type of cell that makes up the immune system and produces antibodies and antitoxins
• Preclinical drug testing: Drug testing done in a laboratory using cells, tissues and live animals
• Vaccination: The process of introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies
• Tobacco Mosaic Virus (TMV): A widespread plant pathogen affecting many species of plants which produces a mosaic pattern on the leaves and limits the plant growth
• Placebo: A substance designed to be indistinguishable from a drug being tested but has no actual effect on the patient
• Salmonella: A bacterial disease that is spread by bacteria ingested in food and can cause a fever, abdominal cramps, vomiting and diarrhoea
• Non-specific defence: General physical and chemical barriers that defend the body against lots of different types of pathogen
• Pathogens: Microorganisms that cause infectious disease
• Pathogens, which include viruses, bacteria, protists and fungi, are microorganisms that cause infectious disease.
• Pathogens can infect plants or animals, spreading through either direct contact, by water or by air.
• Viruses are very small, move into cells and use the biochemistry of it to make many copies of itself, leading to the cell bursting and releasing all of the copies into the bloodstream.
• Bacteria are small, multiply very quickly through dividing by a process called binary fission, and produce toxins that can damage cells.
• Protists are some that are parasitic, meaning they use humans and animals as their hosts, causing damage.
• Fungi can either be single celled or have a body made of hyphae (thread-like structures), can produce spores which can be spread to other organisms.
• Some leaves can droop or curl when touched, allowing them to move away and move insects off their leaves.
• Mimicry is used in some plants to trick animals, with some drooping to look like unhealthy plants so that animals avoid them.
• Chemical defences are used to deter predators or kill bacteria, with poisons coming from foxgloves, tobacco plants, deadly nightshades, and yew, which deter herbivores.
• Mechanical defences include thorns and hairs that make it difficult and painful for animals to eat them, but do not defend against insects.
• Species from the 'ice plant family' have a stone and pebble-like appearance in order to avoid predation.
• Plants can have patterns that appear to look like butterfly eggs, so butterflies do not lay their eggs here in order to avoid competition.
• Communicable (Infectious) Diseases are caused by pathogens, which include viruses, bacteria, protists and fungi, and can infect plants or animals, spreading through either direct contact, by water or by air.
• Viruses are particularly dangerous as they can enter all types of cells, and scientists are yet to develop medicines to cure them.
• Measles symptoms include fever and red skin rash, which can lead to other problems such as pneumonia, encephalitis and blindness.
• HIV symptoms initially include flu-like symptoms, then the virus attacks the immune system and leads to AIDS, a state in which the body is susceptible to many different diseases.
• HIV is spread by sexual contact or exchange of bodily fluids such as blood.
• An example of using antibodies is screening donated blood for HIV infections.
• Monoclonal antibodies can be engineered to treat many different conditions, but they are expensive to develop.
• Plants can also be affected by viral, bacterial and fungal pathogens, and the common signs of plant diseases are: stunted growth, spots on leaves, areas of decay, abnormal growths, malformed stems or leaves, and discolouration.