What are pathogens?
Microoraganisms that cause infectious diseases
What can pathogens infect?
Plants
Animals
How can pathogens be spread?
Direct contact
Water or air
Vectors
What are Vectors?
Organisms that carry and pass on the pathogen without getting the disease
How can the spread of disease be reduced?
Simple hygiene measures e.g. Washing hands
Destroying vectors
Isolating infected individuals
Giving people at risk a vaccination
How did viruses cause damage to cells?
Reproduce rapidly in body cells
Describe measles
- Symptoms are fever and red skin rash
- Measles is spread by breathing in droplets from sneezes and coughs
- fatal complications
- most young people vaccinated
Describe HIV
- spread through sexual contact and sharing body fluids
- first flu like illness
- if untreated virus enters lymph nodes and attacks body’s immune cells
How do bacteria damage cells?
Directly or produce toxins that damage tissues
Describe Salmonella
Type of food poisoning caused by bacteria
Bacteria ingested in food
Secrete toxins which cause fever abdominal cramps vomiting and diarrhoea
Chicken and eggs can contain bacteria
Describe gonorrhea
Sexually transmitted disease
Spread through sexual contact
Thick yellow or green discharge from vagina or penis
Easily hearted with penicillin but resistant trains now appeared
Contraception can act as a barrier and protects
What are Protists?
Single cells organisms that are eukaryotic
Describe malaria
Caused by protists The protists uses mosquito as a vector Passed on by being bitten by mosquito Malaria causes severe fever Kill mosquitos or use nets
Describe rose black spot
Fungal disease
Spread when spores are carried from plant to plant by water or wind
Black spots develop on leaves
Stunted growth due to reducing of photosynthesis
Fungicides can be treatment
Remove affected leaves also is a treatment
Name some non-specific defences of the body that work against all pathogens
Glands in stomach Wall that produce hydrochloric acid that kills bacteria in food
Sebaceous gland in skin that produces sebum-kills bacteria and fungi
The nose traps particles
Enzymes in tears destroy microorganisms
Goblet cells create mucus which traps particles and bacteria
What does the immune system do?
Tries to destroy pathogens that enter the body
What does phagocytosis involve?
Pathogen being surrounded engulfed and digested
How do white blood cells help to defend against pathogens?
Phagocytosis
Production of special protein molecules called antibodies which attach to antigen molecules on the pathogen
Production of antitoxins which are chemicals that neutralise the poisonous effects of the toxins
What happens when someone has a vaccination?
Small quantities of dead or inactive forms of pathogen are injectors into the body
Vaccination stimulates the white blood cells to produce antibodies and to develop immunity
Why does vaccination work?
If a large proportion of the population can be made immune to a pathogen, then the pathogen cannot be spread easily
What are antibiotics?
Medicines that kill bacteria inside the body. However they cannot destroy viruses
What is MRSA?
A strain of bacteria that is resistant to antibiotics
What can we do to reduce the rate at which resistant strains of bacteria develop?
Doctors should not prescribe antibiotics unless they are really needed, for non serious infections and viral infections
Patients must complete their course of antibiotics so that all bacteria are killed and none survive to form resistant strains
What have new pain killers been developed to do?
To treat the symptoms of disease but they do not kill the pathogens
Why are antiviral drugs needed?
That will kill viruses without damaging the body’s tissues
Why are new antibiotics needed?
Because resistant strains of bacteria are developing
What is digitalis?
A heart drug that originates from foxgloves
What is aspirin?
A pain killer that originates from willow
What is penicillin?
Discovered by Alexander Fleming from the Penicillium mould
Why are new medical drugs tested?
New medical drugs have to be tested and trialled before being used to make sure they are safe
If a drug is found to be safe, it is then tested on patients to:
See if it works
Find out the optimum dose
What are double-blind trials?
Some patients are given a placebo and others given the drug
Neither doctors or patient knows who has received drug
What is a monoclonal antibody?
Produced from a single cell that has divided to make many cloned copies of itself
What do monoclonal antibodies bind to?
One type of antigen, so they can be used to target a specific chemical or specific cells in the body
What is a hybridoma?
Combining a mouse cell and a tumour cell
How can monoclonal antibodies be used?
In pregnancy tests
In laboratories
In research
To treat some diseases
How are monoclonal antibodies used in pregnancy tests?
Binds to the hormone HCG found in urine during early pregnancy
How are monoclonal antibodies used in laboratories?
To measure the levels of hormones and other chemicals in blood or to detect pathogens
How are monoclonal antibodies used in research?
To locate or identify specific molecules in a cell or tissue by binding to them with a fluorescent dye
How are monoclonal antibodies used to treat some diseases?
For example in cancer they can be used to deliver a radioactive substance, a toxic drug or a chemical that stops cells dividing, specifically the cancer cells
Why are monoclonal antibodies not widely used?
They created more side effects than expected, so they are not widely used.
Name signs that show a plant may be diseased
Stunted growth Spots on leaves Areas of decay Growths Malformed stems or leaves Discolouration The presence of pests
How can you identify a plant disease?
Consulting a garden manual or website
Taking infected plants to a laboratory
Using testing kits
What can plants be infected by?
Viral bacterial and fungal pathogens as well as insects
Describe TMV
Widespread pathogen
Infects tobacco plants and other plants such as tomatoes
Produces distinctive mosaic pattern of discolouration on the leaves m, which reduces chlorophyll content and affects photosynthesis
It effects growth of plant due to lack of photosynthesis
Why are aphids?
Small insects often known as greenfly or black fly. They feed form phloem taking sugars away from the plant
What does nitrate deficiency cause?
Stunted growth, because nitrates are needed for protein synthesis
What does magnesium deficiency cause?
Chlorosis, because magnesium ions are needed to make chlorophyll
Name some physical defences of plants
Cellulose cell walls
A tough waxy cuticle on leaves
Layers of dead cells around stems, which fall off and take pathogens with them
Name some chemical defences of plants
Antibacterial chemicals which are made by plants such as mint and witch hazel
Poisons deter herbivores, which are made by plants such as tobacco, foxgloves and deadly nightshade
Name some mechanical adaptations of plants
Thorns and hairs to deter animals from animals from eating or touching them
Leaves that droop or curl when touched
Mimicry to trick animals into not eating them or not paying eggs on leaves e.g. The white dead nettle does not sting but it looks very similar to the stinging nettle
