Edexcel GCSE Biology Cells and control
What is a CT scan? - correct answer It shows the shapes of structure in the
brain. A x-ray beam moves in a circle around the head. The detector measures the absorption of these
xrays. A computer uses this information to build a view of images inside the brain. This is a series of
slices. Differences in the shape of the brain can be linked in the differences in which people think and
act, suggesting the functions of those parts of the brain.
What is a PET scan ? - correct answer A PET scan shows brain activity. A
patient is injected with radioactive glucose. More active cells take in more glucose than less active ones
for respiration. The radioactive atoms cause gamma rays, which the scanner detects. More rays come
from active cells.
What happens when there is spinal cord damage? - correct answer It reduces
the flow of information between the brain and parts of the body. Nerve damage can cause loss of
feeling in legs and their use. Damage in the neck and cause quadriplegia (the loss of use of legs and
hands). No adult stem cells can differentiate into neurones so they cannot be used for repair damage.
How does a brain tumour work and how can it be treated? - correct answer
Cancer cells often divide rapidly to form a tumour. A brain tumour may squish some parts of the brain or
it maybe stop it from working. Tumours may be cut out or the cells can be killed by radiotherapy or
chemotherapy. Chemotherapy may not work due to the blood-brain barrier. This is a natural filter that
only allows certain substances to get from the blood to the brain (due to the cells in the capillary walls in
the brain fitting closely together).
What forms the central nervous system? - correct answer brain and spinal
cord, this allows all of the body to communicate using electrical signals called impulses. Nerves make up
the rest of the nervous system.
What is neurotransmission? - correct answer The transmission (travelling) of
impulses
What happens in the nervous system when someone picks up a pencil? - correct answer
Impulses from receptor cells are transmitted by sensory neurones in the optic nerve to our brain. The
