Systolic and diastolic blood pressure
Systolic blood pressure is the maximum pressure that the heart produces.
Diastolic blood pressure is the blood pressure between heart beats.
Explain how immunisation works
A person is injected with a weakened or dead strain of the pathogen, which is incapable of multiplying (it's harmless).
The antigens trigger the production of specific antibodies by the white blood cells.
Long after the pathogen has been dealt with, the white blood cells remain in the blood (memory cells are produced). This means that more antibodies can be produced very quickly if the same pathogen is detected again.
The difference between passive and active immunity
Passive immunity occurs when antibodies are put into an individual's body, rather than the body producing them itself.
Active immunity is when the body produces antibodies in responce to the presence of an antigen.
Difference between monocular and binocular vision
Monocular vision is when the eyes are positioned on either side of the head. Each eye has a wide field of view - can see in front and behind. It is difficult to judge distance or speed as the fields of view only overlap slightly.
Binocular vision is when the eyes are positioned at the front of the head. Each eye has a limited field of view but they over lap so can judge speed and distance accurately.
Functions of the eye
How your body controls heat
Vasdilation - the widening of the blood vessels to increase heat loss from the surface of the skin (cool down).
Vasoconstricion - the narrowing of the blood vessels to reduce heat loss from the surface of the skin (warm up).
How insulin works
Insulin helps to regulate a person's blood sugar levels by converting excess glucose in the blood to glycogen in the liver.
It is used to maintain blood sugar levels in those who are suffering from diabetes.
Types of diabetes
Type 1 - caused when the pancreas fails to produce insulin. It can lead to blood sugar levels rising fatally high. Is controlled by injecting insulin into the body
Type 2 - affects the cells that respond to insulin. They become desensitised to insulin and do not respond. Injecting insulin is no use so is controlled by diet.
Dominant and recessive alleles
Dominant alleles control the development of a characteristic even if present on only one chromosome pair.
Recessive alleles control the development of a characteristic only if a dominant allele isnt present.