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Biology 1a ­ Human Biology
The Nervous System
A stimulus is a change in your environment which you may need to react to.
Eyes ­ light receptors
Ears ­ sound and `balance' receptors
Nose ­ smell receptors
Tongue ­ taste receptors
Skin ­ sensitive to touch, pressure and temperature change…

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o act for a very short time
o act on a very precise area
Hormones:
o Slower message
o Act for a long time
o Act in a more general way

The Menstrual Cycle
FSH:
o Produced by the pituitary gland
o Causes an egg to mature
o Stimulates the…

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Hot day or exercising ­ sweat a lot, so produce less urine which will be
more concentrated. Also lose more water through breath.
o Sugar content ­ foods containing carbohydrate puts glucose into the blood from
gut.
o Temperature ­ enzymes within the human body work best at about 37°C…

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Thalidomide ­ was a sleeping pill (tested for that), but later was found to be effective in
relieving morning sickness in pregnant women (unfortunately wasn't tested for this) ­
caused stunted growth of foetus's arm & legs. Now used to treat leprosy, AIDS & certain
cancers.

Alcohol & Tobacco
Tobacco:…

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Looked at whether cannabis causes brain damage & mental health problems
or leads to further drug taking.
Results are open to different interpretations

Fighting Disease
2 main types of pathogen
o Bacteria:
Very small living cells, which can reproduce rapidly inside your body.
Make you feel ill by:
Damaging your…

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If antibiotics deal with an infection & some of the bacteria are killed, those which survive
may be resistant to the antibiotics & go on to flourish. ­ Which leaves you with an
antibioticresistant strain of bacteria.
E.g. MRSA (methicillinresistant Staphylococcus Aureus) ­ it's resistant to the antibiotic
methicillin.

Treating…

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1. Competition ­ organisms compete with other species for the same resources. ­
can affect the location, size & distribution of populations in the wild.
a) Plants compete with each other for light, water & nutrients from the soil
b) Animals ­ compete with each other for space, food, water…

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Egg & sperm fuses together to form a cell with the full number of chromosomes.

Cloning
Plants can be cloned by 1 of the following:
o Cutting ­ gardeners can take cuttings from good plants & plant them to produce
identical copies of the parent plant. ­ can be produced…

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Theory of evolution = life on Earth began as simple organisms from which all the more
complex organisms evolved.
Species become extinct for 3 main reasons:
1. Environment changes too quickly ­ e.g. destruction of habitat
2. A new predator or disease kills them all ­ e.g. humans hunting them…

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Several different gases in the atmosphere which help keep the heat in, called greenhouse
gases. Main ones are:
o Carbon dioxide ­ humans release this all the time as part of our everyday lives ­
car exhausts, industrial processes, as we burn fossil fuels, deforestation etc.
o Methane ­ rice…

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