Biology Higher Tier GCSE AQA Revision Notes Complete Unit


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  • Created on: 12-06-12 22:45
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Biology revision
Diet and exercise
A balanced diet does a lot to keep you healthy
For good health, your diet must provide the energy you need - but not more
You need to have the right balance of foods as well.
So you need: ... Enough carbohydrates and fats to keep warm and provide energy
... Enough protein for growth, cell repair and cell replacement
... Enough fibre to keep everything moving smoothly through your digestive system
... And tiny amounts of various vitamins and minerals to keep your skin, bones,
blood and everything else generally healthy
People whose diet is not very good person to be malnourished
People's energy needs vary because of who they are...
Your energy to fuel chemical reactions in the body that keep you alive. These reactions are called
your metabolism, and the speed at which it occurs is called your metabolic rate.
There are differences in the resting metabolic rate of different people. E.g. muscle needs more
energy than fatty tissue, so people with a higher proportion of muscle to fat ratio will have a
higher metabolic rate.
Physically bigger people are likely to have a higher metabolic rate - the bigger your body the
more energy is needed.
Men usually have a higher rate than woman as they are slightly bigger and have a larger
proportion of muscle. Other genetic factors may also have some effect.
Regular exercise can boost your resting metabolic rate because it builds muscle.
... And because of what they do
When you exercise, you obviously need more energy so metabolic rate goes up and stays high
for some time.
Temperatures and also affected metabolic rate. When it's cold, your body has to produce more
heat which uses up energy, this also increases metabolic rate. Vice versa
Weight problems
In developed countries problem is too much food
Hormonal problems can lead to obesity, however main issue is about the lack of exercise and a
bad diet
The problems of obesity are related to the blood and joints, e.g. arthritis, diabetes, high blood
pressure and heart disease
In developing countries the problem is often too little
The main problem is the lack of food
The lack of specific food types can cause malnutrition and not enough food and lead to

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The effects of starvation can lead to slower growth and poor resistance to infection
Fighting disease
Bacteria are very small living cells
Bacteria very small cells, which can reproduce rapidly inside your body.
It make you feel ill by doing two things:
1. Damaging your cells b) Producing toxins ­ Poisons
Some bacteria are useful in the right place - such as your digestive system
Viruses are not cells - they're much smaller
Viruses are not cells.…read more

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Immunisation involves injecting dead or inactive microorganisms - these carry antigen, which
will tell your body to produce antibody, these will then attack them - even though it harmless
The MMR vaccine contains weakened versions of the viruses that cause measles, mumps and
rubella stuck together
If the microorganism reappears the body rapidly mass-produce antibodies to kill the pathogen
Vaccinations - Wear off - overtime. So booster injection can be given to increase the level of
antibodies again
Some drugs just relieve symptoms
Painkillers, e.g.…read more

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Sense Organs detect Stimuli
The stimulus is a change in your environment you may need to react to, you need to constantly
monitor what's going on around you so you can respond if you need to
Your five sense organs are - eyes, ears, nose, tongue and skin
They all contain different receptors. Receptors are groups of cells which are sensitive to stimulus.…read more

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The connection between two neurones is called a Synapse
The nerve signals are transmitted by chemicals which diffuse (move) across the gap
These chemicals then set off a new electrical signal in the next neurone
Homeostasis means keeping internal conditions in your body constant (the same). Your body needs to
be kept within narrow limits so it can function at its OPTIMUM (best) level. This means that our body
cells and enzymes are working efficiently.
We have to control:
1.…read more

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Hormones are made and released from glands
Different types of hormones
Adrenaline - Stress response in emergency situations - fight or flight hormones
Sex hormones ­ Males: Testosterone, Females: Oestrogen, FSH etc... - Over 3 to 4 years brings
about puberty and sexual maturity
Pituitary gland - This produces many important hormones including LH, FSH and ADH (controls
water content)
Pancreas - Produces insulin for the control of blood sugar
Menstrual Cycle
There are three main hormones involved:
1.…read more

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Decreasin Contraception methods Contraceptive methods
g fertility Age-related such as condoms etc...…read more


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