Biology 1 revision notes IMPORTANT

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B1a 1 Co-ordination and Control
1.2 Responding to change
1.3 Reflex actions
1.4 The menstrual cycle
1.5 Controlling fertility artificially
1.6 Controlling conditions
B1a 1.1 Responding to Change
· It is the nervous system that enables you to react to your surroundings and co-
ordinates your behaviour
· The nervous system carries electrical signals, or impulses, at fast speeds that allow
you to react to surroundings very quickly
· Controlling many of your body's processes are chemical substances called
hormones, which are made and released, or secreted, by special glands
· Any changes in the surroundings are called stimuli and are picked up by specialised
cells called receptors. These are usually clustered together in special sense
organs, such as your eyes and skin
· Once a sensory receptor picks up a stimulus, the information is sent as an electrical
impulse along special cells called neurones, which are collected in bundles called
nerves. The impulse travels until it reaches the central nervous system (CNS),
made up of the brain and spinal cord
· The cells which carry impulses from sense organs to the CNS are sensory
neurones
· The brain processes the information it is given and sends impulses out along special
cells, which carry impulses from the CNS to the rest of your body. These cells are
called motor neurones and they carry impulses to make the right bits of your body ­
the effector neurones respond
· Effector organs are muscles or glands. Your muscles respond to the arrival of
impulses by contracting. Your glands respond by secreting chemical substances
· The way the nervous system works can be summarises by:
receptor sensory neurone co-ordinator (CNS) motor neurone effector
GCSE Science Revision Page 1 BIOLOGY

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B1a 1.2 Reflex Actions
· Automatic responses in your body happen when, for example, you touch something
hot or sharp and pull your hand away quickly before you even feel the pain.…read more

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B1a 1.5 Controlling Conditions
· Your body's internal environment (i.e. the conditions inside your body) is very
important. Organs cannot work properly if it keeps changing, so many of the
processes taking place inside your body try to keep things as constant as possible.…read more

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B1a 2.3 Fast Food
· The amount of, and type of, fat you have in your body also affects you cholesterol
levels
· Cholesterol is a substance made in the liver, which is transported around the body in
blood.…read more

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B1a 3.2 Legal and Illegal Drugs
· The most common drugs around are everyday drugs, such as caffeine
· Many drugs used for medicinal purposes have no or little effect on your nervous
system, whereas all drugs which people use for pleasure affect your brain and
nervous system, and these are the changes people enjoy taking drugs for
· People might take drugs to help them cope with everyday life, such as alcohol,
nicotine and caffeine.…read more

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B1a 4 Controlling infectious diseases
4.1 pathogens
4.2 defence mechanisms
4.3 using drugs to treat diseases
4.4 changing pathogens and mutation
4.5 developing new medicines
4.6 pathogen immunity
B1a 4.1 Pathogens
· An infectious disease is caused by a microorganism entering and attacking your
body.…read more

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B1a 4.3 Using Drugs to
Treat Disease
· When we have infectious
diseases, we take
medicines, but often they
don't destroy pathogens,
they simply ease the
pain, e.g.…read more

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B1b 5.3 Competition in Animals
· Animals best adapted to their environment are most likely to succeed in competition
· Animals compete for many things, including water, territory and mates.…read more

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