biology - health and disease

• What is the definition of health?


  a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity
• What is a communicable disease?

  A disease that can be transmitted between individuals
• What is ebola, its symptoms, and how is it transmitted?

  It is a virus, which causes a haemorrhagic fever, and is spread by bodily fluids.
• How can we prevent or reduce the transmission of ebola?

  Isolating infected individuals, and sterilising areas where there the virus may present
• What is chalara ash dieback, its symptoms, and how is it transmitted?

  - a fungal disease which infects ash trees

  - symptoms include leaf loss and bark lesions

  - it is spread by fungal spores carried by the wind
• How can we help prevent the transmission of chalara ash dieback?

  removing young, infected ash treess, and replanting with different species, or restricting the movement and importation of ash trees
• What is malaria, its symptoms, and how is it transmitted?

  - a disease caused by a protist

  - effects include damage to red blood cells, and in severe cases, the liver

  - mosquitoes act as vectors which spread the disease
• how can we help prevent the spread of malaria?

  use of mosquito nets and repellent to prevent bites
• what is cholera, its symptoms, the pathogen that causes it, and how is it transmitted?

  - a disease caused by the bacterium VIBRIO CHOLERAE.

  - causes diarrhoea

  - spreads via contaminated water sources
• how can we help prevent the spread of cholera?

  making sure people have access to clean water supplies
• what is tuberculosis, its symptoms, the pathogen that causes it, and how is it transmitted?

  - a disease caused by the bacterium called MYCOBACTERIUM TUBERCULOSIS

  - causes coughing and lung damage

  - bacteria are spread through the air when people cough
• how can be reduce the spread of tuberculosis?

  infected people should avoid public spaces, sleep alone and their homes should be well ventilated
• what are stomach ulcers, its symptoms, the pathogen that causes it, and how is it transmitted?

  - caused by the bacterium HELICOBACTER PYLORI

  - symptoms include sotmach pain, nausea and vomiting

  - bacteria spread via oral transmission - eating infected food, for example
• how can we reduce the spread of stomach ulcers?

  having clean water supplies and hygenic living conditions
• What is chlamidia, its symptoms, and how can we reduce its transmission?

  - an STI caused by the bacterium chlamidia (however it behaves similarly to a virus

  - it doesn't cause symptoms, but can cause infertility in men and women

  - transmission can be reduced by wearing a condom. and screening individuals so they can be treated and avoid sexual contact.
• what is HIV, its symptoms, and how can we reduce its transmission?

  - the Human Immunodeficiency Virus

  - it eventually leads to AIDS

  - the infected person's immune system deteriorates and eventually fails as the disease attacks white blood cells

  - it is spread via bodily fluids

  - transmission can be reduced by drg users not sharing needles, people wearing condoms, and medication can also reduce the chances of an infection person passing the virus on during sex, or to a baby whilst pregnant
• Describe the lytic cycle


  - virus attatches to host cell, and injects its genetic material.

  - virus uses proteins and enzymes from hostto replicate its genetic material, and produce components of viruses

  - viral components assemble

  - host cell lyses (breaks open) releasing new viruses, which infect new cells
• Describe the lysogenic cycle

  Attachment → Entry of viral genome → Viral genome integrates itself into host DNA → Host reproduces (reproducing own and viral genome, but not the actual virus components, as the virus is dormant) → Can induce lytic cycle based on certain factors
• What physical defences do plants have?

  -Waxy cuticle on the stems and leaves

  -Surrounded by cell walls made from cellulose

  -Layers of dead cells around their stems
• What chemical defences do plants have?

  -They produce antiseptics which kill bacterial and fungal pathogens

  -They also produce chemicals to deter pests from feeding on the leaves
• What are possible uses of chemicals produced by plants?

  - Quinine comes from the bark of the cinchona tree, used to be the main treatment for malaria

  - Aspirin is used to relive pain and fever, and was developed from a chemical found in the bark of willow trees
• How can we detect plant diseases?

  - plant pathologists can recognise symptoms in the field

  - some symptoms may be ones of a deficiency, so more of the nutrient needed can be administered in order to rule out (or fix) the deficiency

  - different diseases are spread in different ways, so anaylising the distribution of a disease helps

  - finally laboratory-based testing can help diagnose the diasease
• What physical barriers do humans have against pathogens?

  - skin acts as a barrier, and if it gets damaged, blots clots quickly seal cuts

  - hairs and mucus in your nose trap particles which could contain pathogens

  - cells in your trachea and bronchi produce mucus, which traps pathogens. other cells here have cilia, which waft the mucus bak up th throat to be swallowed, so that the pathogens will be killed by stomach acid
• what chemical barriers do humans have against pathogens?

  - hydrochloric acid in the stomach

  - lysozyme in tears kills bacteria on the surface on the eye
• Describe the immune response

  - every pathogen has unique antigens on its surface

  - when B-lymphocytes find them, they produce complementary antibodies.

  - the antibodies attatch to the antigens, marking them so other white blood cells (phagocytes) can find and engulf them
• What are memory lymphocytes?

  Long-lived descendents of activated lymphocytes, responsible for the speed and effectiveness of the secondary response
• How do vaccines work?

  The vaccine inserts dead or weakened pathogen to produce a primary immune response, triggering the production of memory lymphocytes
• What are the advantaes of immunisation?

  - can help herd immunity

  - some diseases like smallpox have been virtually wiped out by the immunisation process
• what are the disadvantages of immunisation?

  - it doesn't always work

  - some people can have a bad response to a vaccine
• How are monoclonal antibodies produced?

  - mouse immunised by injection of antigen to stimulate production of antibodies

  - plasma cells isolated from spleen

  - plasma cells fuse with tumor cells (myeloma) to form a hybridoma

  - hybridoma produces large amounts of identical antibody molecules
• How do pregnancy tests work?

  The application area contains antibodies for hCG bound to a blue bead. When urine is applied to the application area, and hCG will attach the antibodies, forming an antigen-antibody complex. The urine moves up the stick, carrying any beads with it. The test strip contains fixed antibodies for hCG, which attach to the antibody-antigen complex, stopping it from travelling any further. This creates a blue line, which indicates a positive test.
• How can monoclonal antibodies be used to find blood clots?

  - when blood clots, proteins in the blood join together

  - monoclonal antibodies which attatch to these proteins have been developed

  - you can attatch a radioactive ekement to these antiboies.

  -if you inject them into the body, and then take a picture with a camera which picks up radiation, there will be a bright spot where the clot is
• How can monoclonal antibodies be used to treat cancer?

  - an anti-cancer drug is attatched to monoclonal antibodies, and given to a patient through a drip

  - the antibodies target the cancer cells because they only bind to the tumor markers

  - the drug kills the cancer cells, but doesn't kills any normal body cells near the tumor

  - side affects are lower for this treatment than others because normal treatments can also attack healthy cells
• How do antibiotics work?

  They block the growth and reproduction of bacteria
• How did Fleming discover penicillin?

  There was a mould growing on a agar plate with bacteria growing in it, there was a clear ring around the penicillin
• Describe preclinical testing


  Done in the lab using cells, tissues and then live animals to find how the drug works, how toxic it is, and the best dosage
• Describe clinical testing


  - tested on human volunteers

  - first healthy volunteers to make sure there won't be any harmful side effects when the body is working normally

  - tested on people suffering from the illness, to find optimum dose

  - patients are put into two random groups, one receiving a placebo, one receiving the drug
• How can you grow bacteria in a lab?

  they can be cultured in a culture medium (which contains carbohydrates, minerals, proteins and vitamins they need to grow); for example nutrient broth solution or agar jelly. they should be kept at around 25 degrees because pathogens are less likely to grow at this temperature. all equipment used should be sterile.
• how can you investigate the effect of substances of bacterial growth?

  Place paper disks soaked in antibiotics/antiseptics (or plant extracts) on an agar plate, as well as a control that has not been soaked in antibiotic. A clear area will be left around the disks where the bacteria has died after 48 hours. The more effective the antibiotic against the bacteria, the larger the inhibition zone (clear area).
• How can you use aseptic techniques when growing /experimenting with bacteria in a petri dish?

  - petri dish should be sterilised

  - you can flame the equipment

  - should wipe the desk, and wear gloves