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AQA AS level biology June 2024 Exam Review
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AQA AS level biology June 2024 Exam Review
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AQA AS level biology June 2024 ExamReview
What are the three ways a pathogen can damage hosts cells? -
Answer>> 1) rupturing them to release nutrients inside them
2) breaking down nutrients inside the cell for their own use. This
starves and eventually kills the cell.
3) replicating inside the cells and bursting them when they're
released
What are the two ways pathogens cause disease? - Answer>>
1) production of toxins
2) cell damage
What are the lifestyle factors that can affect your chances of
getting cancer? - Answer>> 1) smoking
2) excessive exposure to sunlight
3) excessive alcohol intake
What are the three surfaces of contact- where pathogens enter
our body? and how do they get in? - Answer>> 1) gas-
exchange system = if you breathe in air that contains pathogens,
most of them will be trapped in mucus lining the lung epithelium.
Some pathogens are able to reach the alveoli where they can
invade cells and cause damage.
2) Skin = if you damage your skin, pathogens on the surface can
enter your bloodstream. blood clots prevent pathogens from
entering.
3) Digestive system = if you eat or drink food that contains
pathogens. Some will survive from the acidic conditions of the
stomach, and invade cells of the gut wall and cause disease.
, Explain the process of phagocytosis. - Answer>> 1) A
phagocyte recognises the antigens on a pathogene
2) The cytoplasm of the phagocyte moves round the pathogen,
engulfing it.
3) The pathogen is now contained in a vacuole or a vesicle in the
cytoplasm of the phagocyte.
4) A lysosome fuses with the phagocytic vacuole and the lytic
enzymes break down with the pathogen
5) The phagocyte presents the pathogens antigens, it sticks the
antigens on its surface to activate other immune system cells.
What is the cellular and humoral response? - Answer>> Cellular
= The T-cells and other immune system cells that they interact
with e.g phagocytes , form the cellular response
Humoral - B cells and the production of antibodies form the
humoral response.
Explain what is meant by a primary response. - Answer>> The
primary response is slow because there aren't many B-cells that
can make the antibody needed to bind to it.
The infected person will show symptoms of the disease while the
body produces enough of the right antibody to overcome the
infection.
T-cells and B-cells produce memory cells. Memory T-cells
remember the specific antigen and will recognise it second time
round. Memory B-cells record the specific antibodies needed to
bind the antigen.
The body is now immune.
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