AQA A LEVEL Biology paper 1 - 6
markers
A farmer thinks a potato crop is infected with potato virus. The farmer obtains a monoclonal antibody
kit for PVY. To make the monoclonal antibodies a scientist first isolates the PVY protein from the virus.
Describe how the scientist would use the protein to produce the PVY monoclonal antibody. (4 marks) -
correct answer1. Inject the protein into a mouse
2. Combine lymphocytes with tumour cells to form hybridoma cells
3. Find a hybridoma that produces a monoclonal antibody specific to PVY
4. Clone the hybridoma to produce many cells to make the antibody
A monoclonal antibody has been produced to treat pancreatic cancer. Explain how the monoclonal
antibody works to treat pancreatic cancer. (3 marks) - correct answerMonoclonal antibody is attached
to a drug, it will only attach to target antigen of cancer cells so the drug will bind to cancer cells to stop
them dividing.
A person has a tumour blocking the tube leading from the gall bladder to the small intestine. Explain
why this person would have difficulty digesting fat. (5 marks) - correct answerLess bile reaches the small
intestine so no emulsification of fat so smaller surface area for lipase to break down fat. pH of small
intestine is not neutralised so lipase is not at its optimum pH to break down fat.
Compare the structure and function of xylem tissue to phloem tissue. (6 marks) - correct answer- xylem
is made of dead cells while the phloem is made of living cells
- phloem have pores in their end walls whereas the xylem does not
- xylem is hollow and does not contain a cytoplasm
- xylem transports water and mineral ions whereas the phloem transports dissolved sugars
- xylem is involved in transpiration whereas the phloem is involved in translocation
Compare the structure of a red blood cell with the structure of a plant cell. (6 marks) - correct answer-
red blood cells have no nucleus but a plant cell does
- plant cells are much larger than compared to red blood cells
- plant cells have chloroplasts whereas red blood cells do not
, - they both have a cytoplasm and cell membrane
- the red blood cells have a biconcave disk but a plant has many shapes
Compare the structure of an artery with the structure of a vein. (3 marks) - correct answer- an artery has
a smaller lumen than a vein because an artery needs to maintain the strong blood pressure while a vein
has lower blood pressure
- arteries have a thicker layer of muscle tissue while veins have a thinner layer
- arteries have a thicker layer of elastic tissue
Describe how a student could test cow's milk to show whether it contains protein and different types of
carbohydrates. (6 marks) - correct answerBiuret reagent tests for protein:
- add biuret to milk
- solution will turn from blue to purple if positive
Benedicts test for sugars:
- add benedicts reagent to milk
- boil
- solution will turn from blue to red if positive
Iodine test for starch:
- add iodine solution to milk
- solution will turn from orange to blue
Describe how clinical trials should be carried out. (6 marks) - correct answer- tested on live cells
- tested on animals
- tested on healthy volunteers at low dose to test toxicity
- tested on some patients with the disease to test dosage and side effects
- tested during a double blind trial for efficacy where neither patient nor doctor knows who has the
placebo
Describe how the human body: prevents pathogens from entering and defends itself against pathogens
inside the body. (6 marks) - correct answer- skin acts as a barrier to prevent pathogens entering
markers
A farmer thinks a potato crop is infected with potato virus. The farmer obtains a monoclonal antibody
kit for PVY. To make the monoclonal antibodies a scientist first isolates the PVY protein from the virus.
Describe how the scientist would use the protein to produce the PVY monoclonal antibody. (4 marks) -
correct answer1. Inject the protein into a mouse
2. Combine lymphocytes with tumour cells to form hybridoma cells
3. Find a hybridoma that produces a monoclonal antibody specific to PVY
4. Clone the hybridoma to produce many cells to make the antibody
A monoclonal antibody has been produced to treat pancreatic cancer. Explain how the monoclonal
antibody works to treat pancreatic cancer. (3 marks) - correct answerMonoclonal antibody is attached
to a drug, it will only attach to target antigen of cancer cells so the drug will bind to cancer cells to stop
them dividing.
A person has a tumour blocking the tube leading from the gall bladder to the small intestine. Explain
why this person would have difficulty digesting fat. (5 marks) - correct answerLess bile reaches the small
intestine so no emulsification of fat so smaller surface area for lipase to break down fat. pH of small
intestine is not neutralised so lipase is not at its optimum pH to break down fat.
Compare the structure and function of xylem tissue to phloem tissue. (6 marks) - correct answer- xylem
is made of dead cells while the phloem is made of living cells
- phloem have pores in their end walls whereas the xylem does not
- xylem is hollow and does not contain a cytoplasm
- xylem transports water and mineral ions whereas the phloem transports dissolved sugars
- xylem is involved in transpiration whereas the phloem is involved in translocation
Compare the structure of a red blood cell with the structure of a plant cell. (6 marks) - correct answer-
red blood cells have no nucleus but a plant cell does
- plant cells are much larger than compared to red blood cells
- plant cells have chloroplasts whereas red blood cells do not
, - they both have a cytoplasm and cell membrane
- the red blood cells have a biconcave disk but a plant has many shapes
Compare the structure of an artery with the structure of a vein. (3 marks) - correct answer- an artery has
a smaller lumen than a vein because an artery needs to maintain the strong blood pressure while a vein
has lower blood pressure
- arteries have a thicker layer of muscle tissue while veins have a thinner layer
- arteries have a thicker layer of elastic tissue
Describe how a student could test cow's milk to show whether it contains protein and different types of
carbohydrates. (6 marks) - correct answerBiuret reagent tests for protein:
- add biuret to milk
- solution will turn from blue to purple if positive
Benedicts test for sugars:
- add benedicts reagent to milk
- boil
- solution will turn from blue to red if positive
Iodine test for starch:
- add iodine solution to milk
- solution will turn from orange to blue
Describe how clinical trials should be carried out. (6 marks) - correct answer- tested on live cells
- tested on animals
- tested on healthy volunteers at low dose to test toxicity
- tested on some patients with the disease to test dosage and side effects
- tested during a double blind trial for efficacy where neither patient nor doctor knows who has the
placebo
Describe how the human body: prevents pathogens from entering and defends itself against pathogens
inside the body. (6 marks) - correct answer- skin acts as a barrier to prevent pathogens entering
