OCR 21st Century Science: B2- Keeping Healthy

This is detailed overview of the B2 module in OCR 21st Century Science. 


-CGP GCSE Core Science OCR 21st Century Science Revision Guide.

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B2-Keeping Healthy
Ultimate Revision Guide…read more

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Microorganisms and Disease
· Microorganisms that cause disease are called Pathogens.
· Microorganisms that cause disease: Bacteria, Protozoa, Fungi and
· Most microorganisms reproduce fastest in warm, damp places. (Like the
human body)
· Once microorganisms reproduce, they cause an infection.
· Symptoms can be caused by cell damage or by toxins (chemicals that
Microorganisms produce)
· The body has natural barriers to keep microorganisms out
· The skin; rapid repair if you are cut, your sweat; forms an extra protective
layer, your tears; contain enzymes that kill bacteria. If any microorganisms
do get into your body through food, the hydrochloric acid in your
stomach will kill them.…read more

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The Immune System
· The immune system's role is to deal with any pathogens that enter the body. Any
immune response always involves white blood cells.
· The white blood cells are able to detect things that are `foreign' to the body.
· White blood cells then engulf the microbes and digest them.
· These type of white blood cells are non-specific- they will attack anything.
· A different type of white blood cell attacks specific microorganisms.
· These white blood cells recognise particular antigens. Antigens trigger immune
· This kind of white blood cells produces antibodies. Antibodies latch onto
invading microorganisms and do one of three things:
1. Mark the microorganism so other white blood cells can engulf and digest
2. Bind to and neutralise viruses or toxins.
3. Some can even attach to bacteria and kill them directly.
· Once the right white blood cell recognises the antigens it divides into more
identical cells. The white blood cells stay in the blood after the original infection
so, it can fight the microorganism if it returns. This is called immunity.…read more

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· Vaccination involves injecting dead or inactive microorganisms.
· They still carry the same antigens which means your body produces
antibodies to attack them- even though it is harmless.
· If you are actually infected, the white blood cells can rapidly mass-
reproduce antibodies to kill off the pathogen.
· However, vaccinations cannot be made for every disease.
· Changes to DNA of a microorganism is called mutation and it is
completely random.
· Some microorganisms mutate often, making it hard to develop vaccines
because the changes in their DNA can lead to different antigens.
· The virus that causes influenza mutates very quickly. New vaccines are
developed on a regular basis.
· The HIV virus damages the immune system, so if your vaccinated your
immune system won't respond as it should. It also has a high mutation
rate (Yikes!)…read more

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Vaccination-Pros and Cons
Pros Cons
Big out
1) Big outbreaks of diseases- 1) Vaccinations can never be
called epidemics- can be completely safe for
prevented of a large everyone, because
percentage of population individual immune systems
is vaccinated. That way, will have different
even the people who aren' reactions to the vaccine.
t vaccinated are unlikely to
catch the disease.
2) Some disease, such as 2) Vaccines sometimes cause
smallpox, have been virtually side effects, which are worse
wiped out by vaccination in some people than in
programmes others. They feel the risks
outweigh the benefits of
having the vaccine.…read more

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· Antibiotics can kill bacteria and fungi, but NOT viruses.
· Antibiotics are useful for clearing up infections your immune system cannot
deal with.
· Sometimes, bacteria can evolve and become antibiotic-resistant.
· Like all organisms, microorganisms sometimes develop random mutations.
· This can lead to changes in the microorganism's characteristics, which may
lead to the organism being less effected by a particular antibiotic.
· This new resistant microorganism may reproduce and create a whole antibiotic-
resistant population (Not good!) They are not easily removed once they are
· Superbugs are resistant to most known antibiotics. They are being far to
· The more antibiotics are used, the bigger the antibiotic-resistance problem
· If there are too many resistant individuals left behind, they may create a whole
new resistant army!
· It is important that you finish your course of antibiotics as the hardcore ones
could still be there.
· Also do not use antibiotics unless it is vital. Antibiotics creates a situation
where naturally resistant microorganisms can reproduce.…read more

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Fantastic! Can you make this for the other topics too - B1, B3, B4, C1, C2 etc? It would be a great help :)

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