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AQA GCSE Biology ­ Unit 1 summary notes
















AQA




GCSE Biology




Unit 1




Summary Notes














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AQA GCSE Biology ­ Unit 1 summary notes




11.1 Internal Control

The Nervous System

The nervous system enables humans to react to their surroundings and coordinate their
behaviour.
Information from receptors passes along cells (called neurones) in nerves to the brain.
Nerve impulses are electrical signals that travel along neurones.…

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Reflexes

A reflex is a rapid automatic response to a stimulus, which does not involve conscious
control.

Functions:
Protection from dangerous stimuli.
Eg hand withdrawal from a hot object.
Maintenance of body processes
eg. Heart rate and breathing
Muscle coordination and posture…

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Hormones

Many processes within the body are coordinated by chemical substances called hormones.
Hormones are secreted by glands and are transported to their target organs by the
bloodstream.
Hormones regulate the functions of many organs and cells.

Hormones in the menstrual cycle…

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Multiple births ­ some babies may die.
People do not like embryos to be used for research.
Oral contraceptives
Contain hormones that inhibit FSH production so that no eggs mature.

Benefits:
It can reduce population growth in the developed world.

Concerns:
Health…

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Higher concentration of ions than in body fluids
Water is drawn into the gut ­ this dehydrates you not sensible in a sports drink!





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11.2 Healthy lifestyles

Balanced Diet

A healthy diet contains the right balance of different foods.
A healthy diet contains the right amount of energy.
It will provide carbohydrates for energy.
It will provide fat for energy and insulation.
It will provide protein…

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In the developed world too much food and too little exercise are leading to high levels of
obesity.

Some diseases linked to excess weight:
arthritis (worn joints)
diabetes (high blood sugar)
high blood pressure
heart disease.

Malnourishment

A person is malnourished if…

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11.3 Drugs

Drug Abuse

Drugs can be beneficial but may harm the body.
Many drugs derived from natural substances have been known to indigenous peoples for
many years.
Some people use drugs recreationally.
Some of these recreational drugs are more harmful than…

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11.4 Infectious Disease

Pathogens

Microorganisms that cause infectious disease are called pathogens.

Bacteria

Bacteria are very small singlecelled organisms.
Not all cause disease.
Pathogenic bacteria reproduce rapidly inside the body and may produce poisons (toxins)
which make us feel ill.
Example: E.coli…

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