What is a vaccine, and how does it help protect against some pathogens?
A vaccine is a dead or inactive form of a pathogen which, when injected into the body, can protect against bacterial and viral pathogens.
White blood cells produce antibodies against the vaccine, and memory cells are made so antibodies can be made faster next time so the virus is killed before symptoms occur.
What did Semmelweiss do and why did other doctors not accept his ideas at first?
Semmelweiss realised that infection could be transferred from person to person, and that washing hands removes pathogens from them.
Other doctors did not accept his ideas at the time because they didn't know about microorganisms back then.
What is the metabolic rate and what affects it?
How fast chemical reactions take place in the body.
Metabolic rate is effected by genes, age, gender and muscle:fat ratio.
What is a pathogen, and what can each type do?
A pathogen is a microorganism which causes an infectious disease. Bacteria produce toxins which make people feel ill. Viruses reproduce in and then kill host cells. Pathogens can also be fungi.
What is a balanced diet?
Why do different people need different amounts of energy?
A balanced diet includes everything needed to keep the body healthy. Different people need different amounts of energy because metabolic rate varies from person to person.
To keep bacteria cultures pure you must:
-Sterilise Petri dishes before use.
-Sterilise inoculating loop under the flame of a Bunsen burner.
-After putting in the bacteria, close the lid as soon as possible.
-Seal the Petri dish lid with sellotape to prevent microorganisms escaping or entering.
-Keep incubated in maximum 25*C and don't sellotape all the way round to prevent growth of harmful anaerobic bacteria.
What is the advantage of vaccinating a large proportion of the population against a virus?
Reduces spread of infection/ less likely to get an epidemic.
Why are viruses difficult to destroy?
Viruses reproduce inside our cells, so any treatment could also damage our cells.
What are the two types of cholesterol?
LDL- low density lipoproteins aka: bad= because fat is less dense than muscle, so there is more fat in LDLs.
HDL- high density lipoproteins aka: good.
How does the body prevent most pathogens getting in, and how does it get rid of pathogens that have gotten in?
Skin, eyelashes and tears stop bacteria getting in. Mucus traps pathogens and stomach acid (hydrochloric acid) kills them.
Give a benefit and problem with vaccinations.
Vaccination protects individuals and society from the effects of disease.
Some vaccines cause side effects which may be mild or serious.
Why can't antibodies be used to treat viruses (2 marks)?
Antibiotics only kill bacteria (1) and don't work on viruses because viruses live inside cells (1).
How can antibiotic resistance occur and what can this lead to?
If a pathogen is not completely killed off, it may mutate to a new resistant strain and spread rapidly. Some new strains can cause epidemics (country) and pandemics (world).
The MRSA 'superbug' is a resistant bacterium that has evolved through natural selection.
How do white blood cells defend the body?
1. They can ingest pathogens.
2. They produce antibodies, which bind to antigens on the surface of the pathogens and clumps them all together to be ingested.
3. They produce anti toxins to counteract toxins pathogens produce.
Describe what happens in the body after immunisation to stop a person catching (e.g: measles) in the future (3)
1. White blood cells.
2. Make antibodies.
3. Antibodies are quickly produced if they get measles again and kill it before symptoms occur.
Who discovered penicillin?
Alexander Fleming in 1928.
What happens to your body if you take in too much energy or too few vitamins?
If you eat more food than needed your mass will increase.
If the diet is unbalanced you can become malnourished.
What is meant by a balanced diet?
Right amount of energy (1) for individual needs (1).
Why is high cholesterol bad?
Cholesterol can build up in artery walls, blocking blood flow.
This is especially dangerous in coronary arteries and can lead to heart disease/attacks.
Give examples of what different weight problems can lead to.
Obesity can lead to type 2 diabetes.
Starvation can make it hard to walk and cause deficiency diseases due to lack of vitamins and minerals.
How can people change their lifestyles to help lower blood cholesterol levels?
By exercising regularly, a person can increase their metabolic rate and lower high cholesterol levels.
Why do we need cholesterol?
We need 'good' cholesterol for cell membranes and to make vital substances.
Vaccination against the measles virus will not protect the child against the rubella virus.
The rubella antigen is a different shape so different antibodies are needed.
What is the difference between anti-biotics and painkillers?
Painkillers relieve the symptoms of a disease but do not kill the pathogen, whilst anti-biotics kill infective bacteria in the body.