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Title: GCSE Biology 2.5 - Response and Regulation
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A.) This is one of eight topics in the unit.
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A.) This is one of eight topics in the unit.
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2
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g
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The retina
•
•
•
The pupil
•
•
a hole in the centre of the iris
allows light to enter
The blind spot
The iris
•
•
•
muscles that alter the size of the pupil
to control the amount of light
entering
where the optic nerve leaves the eye
where there are no light-sensitive
cells
The optic nerve
The lens
•
a light sensitive layer
where images are formed
where impulses are sent to the optic
nerve
•
changes shape to focus light onto
retina
12
carries impulses from the retina to
the brain
Homeostasis
•
regulating the conditions inside the body to keep them constant and protected from harmful
effects
Hormones
•
•
•
chemical messengers
carried by the blood
control many body functions
Glucose levels
•
need to be kept within a constant range
Insulin
•
•
•
•
a hormone
a protein
released by the pancreas into the blood
causes the liver to reduce the glucose level by converting glucose into insoluble glycogen
then storing it
Diabetes
•
•
a common disease in which a person has a high blood glucose level
detected by glucose in urine using Benedict’s solution
Type 1 diabetes
•
caused by the body not producing insulin
Type 2 diabetes
•
caused by the body cells not properly responding to the insulin that is produced
The methods of treating diabetes
•
•
•
•
regularly injecting insulin
a low sugar diet
a low carbohydrate diet
a possible transplant of pancreatic tissue
13
Metabolism
•
•
operates only within a narrow range of temperature and pH
requires appropriate nutrients and water
The structure of a section through the skin
Blood
vessels
•
Body temperature regulation when too warm
•
•
vasodilation
sweating
Vasodilation
•
•
•
The arterioles get wider
...
The amount of heat loss from the skin increases
...
The sweat travels up the sweat duct
...
The sweat evaporates and takes excess body heat with it
...
The hair is raised
...
Vasoconstriction
•
•
•
The arterioles get narrower
...
The amount of heat loss from the skin decreases
...
illustrated by the control of glucose levels by insulin and glucagon and by the control
of body temperature
Phototropism
•
•
the positive response of plant shoots to light
due to a plant hormone called auxin
Gravitropism
•
the positive response of plant shoots to gravity
15
Lifestyle choices
•
affect some conditions
Alcohol
•
•
•
changes various chemical processes in the body, including reaction time
may cause people to become dependent on, addicted to and suffer withdrawal
symptoms without it
can cause long-term physical damage, e
...
liver, circulatory and heart diseases
Drugs
•
•
misused
affect people’s bodies
Obesity and type 2 diabetes
•
There is a link between rising levels of obesity and increasing levels of type 2
diabetes
Title: GCSE Biology 2.5 - Response and Regulation
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A.) This is one of eight topics in the unit.
Description: These are concise, exam-focused notes made using the WJEC specification and BBC Bitesize. (I achieved an A.) This is one of eight topics in the unit.