B6.3 Flashcards
What can Human papilloma virus (HPV) lead to?
Certain types of cervical cancer
What can Human immunodeficiency virus (HIV) lead to?
Tuberculosis
How can pathogens spread between animals?
- through cuts in the skin
- through the digestive system (when food and drink is shared)
- through the respiratory system
- through the reproductive system (during intercourse)
How can pathogens spread between plants?
- vectors, such as insects
- soil and water in which the plants grow
- direct contact of sap from infected to healthy
- the wind, fungal spores can be blown between plants
What is the ‘incubation period’?
The time delay between harmful microorganisms entering your body, and you feeling unwell.
How does a virus ‘take over’ an organisms cells?
The virus attacks a cell and inserts its genes. It ‘tells’ the nucleus to copy its genes and new viruses are made. The cell then bursts releasing the new viruses and destroying your cell.
How do farmers prevent the spread of disease in plants and animals?
- diseased plant material is normally burnt to prevent the disease spreading
- livestock cannot be moved
- animals may be treated using drugs
Example of fungi in animals
Athletes foot
An example of a viral plant disease
Tobacco Mosaic Virus
Symptoms of tobacco mosaic virus
- mottled or discoloured leaves, it does this by preventing chloroplasts from forming, which stunts the growth of the plant
- almost never kills the plant, but lowers quality and quantity of crop they produce
Example of bacterial plant disease
Agrobacterium tumefaciens
Example of a fungal plant disease
Powdery mildew
Symptoms of powdery mildew
Displaying white powdery spots on the leaves and stems
What are the two types of plant defences against communicable diseases?
Physical defences
Chemical defences
Example of physical plant defences
Waxy cuticle
Cell wall
Ways to identify plant diseases in the field
Microscopy
Observation
How does skin act as a defence mechanism?
It’s a physical barrier. Sweat glands also help to kill microorganisms.
How does acid in the stomach act as a defence mechanism?
Kills pathogens present in contaminated food or drink
How do tears act as a defence mechanism?
They contain lysozymes which are enzymes that destroy bacteria
What is the immune systems main form of defence?
White blood cells
What are the two types of white blood cells?
Lymphocytes and phagocytes
What do phagocytes do?
They engulf the microorganisms and then make enzymes that digest the microorganisms.
What do lymphocytes do?
They make antitoxins or antibodies.
Where are monoclonal antibodies produced and what are they produced with?
In the laboratory using special cells known as hybridomas.
What are hybridomas?
A fusion of myelomas (cancer cells) and lymphocytes
How are monoclonal antibodies produced?
Genetically modified mice are injected with the required antigen. Their bodies then produce antibodies to that specific antigen. The antibody-producing lymphocyte cells are then collected. These cannot survive outside the body so they are fused with myeloma cells (cancerous cells) from the bone marrow, which reproduce indefinitely.
As the hybridoma cells reproduce, they form clones. Each clone produces the required antibody, which is harvested. These proteins are called monoclonal antibodies.
What are vaccines?
They usually contain small amounts of weakened or dead versions of a pathogen. They are injected into the body and cause your lymphocyte cells to produce antibodies to the pathogen.
What do antiseptics do?
Kill or neutralise all types of pathogen, but do not damage the human tissue.
e.g. alcohol or iodine
What do antivirals do?
They are drugs that destroy viruses, usually preventing them from replicating.
What are antibiotics?
Drugs that kill bacteria without damaging your cells.
What does aseptic technique do?
Prevents foreign microorganisms from being introduced into a test sample.
What does aseptic mean
Without microorganisms
Why should you wash working areas with alcohol before and after working?
To ensure that no microorganisms are present in the working area
Why should you wear gloves if at risk of working with pathogens?
To prevent microorganisms passing from a sample to your skin
Why should you work close to a Bunsen burner flame?
To prevent unwanted microorganisms from falling into an open sample.
Describe how some plants use chemicals as a defence against pathogens.
Some plants produce antimicrobial chemicals to kill pathogen or inhibit their growth.
How would you sterilise and inoculating loop?
By passing it through a hot flame
Why are cultured incubated at a maximum of 25 degrees Celsius in schools?
Harmful bacteria are more likely to grow above this temperature.
Why are tumour cells used to produce hybridomas?
Tumour cells can be grown easily, because they divide a lot
What do antibodies bind to on the surface of cancer cells?
Tumour markers