AQA AS level biology(2023 A+)
What are the three ways a pathogen can damage hosts cells? - 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? - 1) production of toxins
2) cell damage
What are the lifestyle factors that can affect your chances of getting cancer? - 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? - 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. - 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? - 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. - 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.
Explain what is meant by the secondary response. - If the same pathogen enters the body again, the
immune system will produce a quicker, stronger immune response.
Memory B-cells divide into plasma cells that produce the right antibody to the antigen. Memory T-cells
divide into the correct type of T cells to kill the cell carrying the antigen.
The secondary response often gets rid of the pathogen before you begin to show any symptoms.
Explain how monoclonal antibodies target cancer - 1) Cancer cells have antigens called tumour markers
that are not found on body cells.
2) Monoclonal antibodies can be made that will bind to the tumour markers.
What are the three ways a pathogen can damage hosts cells? - 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? - 1) production of toxins
2) cell damage
What are the lifestyle factors that can affect your chances of getting cancer? - 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? - 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. - 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? - 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. - 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.
Explain what is meant by the secondary response. - If the same pathogen enters the body again, the
immune system will produce a quicker, stronger immune response.
Memory B-cells divide into plasma cells that produce the right antibody to the antigen. Memory T-cells
divide into the correct type of T cells to kill the cell carrying the antigen.
The secondary response often gets rid of the pathogen before you begin to show any symptoms.
Explain how monoclonal antibodies target cancer - 1) Cancer cells have antigens called tumour markers
that are not found on body cells.
2) Monoclonal antibodies can be made that will bind to the tumour markers.
