2026 AQA A Level Biology with
Merged Question Papers & Mark
Schemes
what are killer t-cells? -Answer--- cytotoxic cells
- bind to non-self antigens
how to killer t-cells work? -Answer--1. virus attaches to and enters host cell
2. viral DNA causes host cell to express viral antigens on its surface
3. killer t-cells attaches to viral antigens on infected cells
4. killer t-cells induces death of infected cell (apoptosis)
what is apoptosis? -Answer--programmed cell death
how do killer t-cells destroy cancer? -Answer--- cancerous = mutations
- mutations = abnormal antigens
- killer t-cell binds to abnormal antigens
- killer t-cells induces death of cancerous cell
What does perforin do? -Answer--creates holes in the cell membranes in order to
destroy the infected cell
what do helper t-cells do? -Answer--- produce cytokines
- cytokines stimulate b-cells to divide into plasma and memory cells
- activate killer t-cells
define helper t-cells -Answer--help humoral response by involvement in the
maturation of b-cells and by triggering the production of antibodies by b-cells
what do suppressor t-cells do? -Answer--- halt immune response
- prevent wastage of energy and resources
- prevent overactive immune response
- causes reduction of white blood cells after being ill
define memory t-cells -Answer--work in the same way as memory b-cells, ensuring
rapid response on subsequent exposure to the same non-self antigens
,define suppressor t-cells -Answer--regulate the immune response by suppressing
activity of killer t-cells and b-cells
define 'microorganism' -Answer--organism that is too small to be seen without a
microscope
define 'pathogen' -Answer--microorganism that causes disease
outline phagocytosis -Answer--1. phagocyte follows conc gradient of
chemoattractants
2. phagocyte attaches to pathogen
3. pathogen engulfed and placed in a vesicle (phagosome)
4. lysosomes migrate to phagosome and bind with it to form a phagolysosome
--> lytic enzymes released from lysosome
5. pathogen digested
6. useful parts absorbed
7. all waste products released by exocytosis
8. non-self antigens of the pathogen displayed on the phagocytes surface
(antigen-presenting)
where are t-cells made? -Answer--thymus gland
where do b-cells mature? -Answer--bone marrow
what do b-cells do? -Answer--- humoral response
- release antibodies
- complementary to a specific antigen
what response are plasma cells? -Answer--primary
what response are memory b-cells? -Answer--secondary
outline the humoral response -Answer--1. antigen attaches to complementary
antibody on b-cell
2. antigen taken into cell (endocytosis)
3. presented on cell surface membrane
4. t-helper cells bind to antigen and stimulate b-cell to divide
what does mitosis do in humoral response? -Answer--- forms clones of b-cells
(plasma and memory)
- clonal response
what do clones do? -Answer--each clone can produce one type of antibody
(monoclonal) which can be used in medicine
,outline plasma cells -Answer--- primary response
- secrete antibodies
- only survive for a few day
- slow response = person gets ill before pathogen is killed
outline memory cells -Answer--- secondary response
- circulated in blood and tissue fluid
- divide rapidly
- rapid response so person doesn't get ill
what is an antibody? -Answer--y-shaped globular protein produced by b-cells
where are antibodies produced? -Answer--plasma b-cells
what are antibodies made of? -Answer--4 polypeptide chains -- 2 heavy, 2 light
what are the two regions an antigen is made of? -Answer--- variable
- constant
what is special about the variable region? -Answer--complementary and specific to
an antigen
what are the chains bonded by? -Answer--disulphide bridge
why do antibodies have a hinge region? -Answer--to allow the antibody to move to
bind to more than one antigen
what is 'monoclonal antibody production' -Answer--the process by which large
quantities of antibodies (targeted against a particular antigen) can be produced
how are monoclonal antibodies produced? -Answer--- mouse immunised by injection
of antigen to stimulate production of antibodies
- plasma cells isolated from spleen
- plasma cells fuse with tumor cells to form a hybridoma
- hybridoma produces large amounts of identical antibody molecules
what is the scientific term for a tumor cell? -Answer--myeloma
what can be monoclonal antibodies be used as? -Answer--specific probe to track
down and purify specific protein that induced its transformation
what needs to happen to monoclonal antibodies before human use?
-Answer--humanisation
, why do monoclonal antibodies need to be 'humanised' before used by humans?
-Answer--to stop the trigger of an immune response
what are monoclonal antibodies used for? -Answer--- pregnancy tests
- diagnostic tools for AIDS
- industrial production of interferon
what is a vaccine? -Answer--a dead or weakened version of a disease with relevant
antigens
what is a vaccination? -Answer--introduction of a vaccine containing appropriate
disease antigens into the body to induce artificial immunity
how do vaccines work? -Answer--- pathogen stimulaties wbc into making antigens
- dead or inactive pathogen enter body via injection
- antibodies stick to antigens and clump them together
- memory cells = immunity
what are the pros of immunisation? -Answer--- protected from certain diseases
- economic benefits
- eradicate diseases
- prevent epidemics
what are the cons of immunisation? -Answer--- chance of contracting diseases from
vaccine
- religions might be against it
- side effects
- only work for a certain amount of time
- antigenic variability
- certain pathogens hide from immune system
what is HIV -Answer--a retrovirus that attacks the body's immune system
what are the modes of transmission of HIV -Answer--- blood (transfusions)
- sharing needles
- breast feeding/ giving birth
- sex
what is herd immunity'? -Answer--vaccinating enough people so there isn't enough
hosts for the virus to spread
define 'epidemic' -Answer--infection of a country
Merged Question Papers & Mark
Schemes
what are killer t-cells? -Answer--- cytotoxic cells
- bind to non-self antigens
how to killer t-cells work? -Answer--1. virus attaches to and enters host cell
2. viral DNA causes host cell to express viral antigens on its surface
3. killer t-cells attaches to viral antigens on infected cells
4. killer t-cells induces death of infected cell (apoptosis)
what is apoptosis? -Answer--programmed cell death
how do killer t-cells destroy cancer? -Answer--- cancerous = mutations
- mutations = abnormal antigens
- killer t-cell binds to abnormal antigens
- killer t-cells induces death of cancerous cell
What does perforin do? -Answer--creates holes in the cell membranes in order to
destroy the infected cell
what do helper t-cells do? -Answer--- produce cytokines
- cytokines stimulate b-cells to divide into plasma and memory cells
- activate killer t-cells
define helper t-cells -Answer--help humoral response by involvement in the
maturation of b-cells and by triggering the production of antibodies by b-cells
what do suppressor t-cells do? -Answer--- halt immune response
- prevent wastage of energy and resources
- prevent overactive immune response
- causes reduction of white blood cells after being ill
define memory t-cells -Answer--work in the same way as memory b-cells, ensuring
rapid response on subsequent exposure to the same non-self antigens
,define suppressor t-cells -Answer--regulate the immune response by suppressing
activity of killer t-cells and b-cells
define 'microorganism' -Answer--organism that is too small to be seen without a
microscope
define 'pathogen' -Answer--microorganism that causes disease
outline phagocytosis -Answer--1. phagocyte follows conc gradient of
chemoattractants
2. phagocyte attaches to pathogen
3. pathogen engulfed and placed in a vesicle (phagosome)
4. lysosomes migrate to phagosome and bind with it to form a phagolysosome
--> lytic enzymes released from lysosome
5. pathogen digested
6. useful parts absorbed
7. all waste products released by exocytosis
8. non-self antigens of the pathogen displayed on the phagocytes surface
(antigen-presenting)
where are t-cells made? -Answer--thymus gland
where do b-cells mature? -Answer--bone marrow
what do b-cells do? -Answer--- humoral response
- release antibodies
- complementary to a specific antigen
what response are plasma cells? -Answer--primary
what response are memory b-cells? -Answer--secondary
outline the humoral response -Answer--1. antigen attaches to complementary
antibody on b-cell
2. antigen taken into cell (endocytosis)
3. presented on cell surface membrane
4. t-helper cells bind to antigen and stimulate b-cell to divide
what does mitosis do in humoral response? -Answer--- forms clones of b-cells
(plasma and memory)
- clonal response
what do clones do? -Answer--each clone can produce one type of antibody
(monoclonal) which can be used in medicine
,outline plasma cells -Answer--- primary response
- secrete antibodies
- only survive for a few day
- slow response = person gets ill before pathogen is killed
outline memory cells -Answer--- secondary response
- circulated in blood and tissue fluid
- divide rapidly
- rapid response so person doesn't get ill
what is an antibody? -Answer--y-shaped globular protein produced by b-cells
where are antibodies produced? -Answer--plasma b-cells
what are antibodies made of? -Answer--4 polypeptide chains -- 2 heavy, 2 light
what are the two regions an antigen is made of? -Answer--- variable
- constant
what is special about the variable region? -Answer--complementary and specific to
an antigen
what are the chains bonded by? -Answer--disulphide bridge
why do antibodies have a hinge region? -Answer--to allow the antibody to move to
bind to more than one antigen
what is 'monoclonal antibody production' -Answer--the process by which large
quantities of antibodies (targeted against a particular antigen) can be produced
how are monoclonal antibodies produced? -Answer--- mouse immunised by injection
of antigen to stimulate production of antibodies
- plasma cells isolated from spleen
- plasma cells fuse with tumor cells to form a hybridoma
- hybridoma produces large amounts of identical antibody molecules
what is the scientific term for a tumor cell? -Answer--myeloma
what can be monoclonal antibodies be used as? -Answer--specific probe to track
down and purify specific protein that induced its transformation
what needs to happen to monoclonal antibodies before human use?
-Answer--humanisation
, why do monoclonal antibodies need to be 'humanised' before used by humans?
-Answer--to stop the trigger of an immune response
what are monoclonal antibodies used for? -Answer--- pregnancy tests
- diagnostic tools for AIDS
- industrial production of interferon
what is a vaccine? -Answer--a dead or weakened version of a disease with relevant
antigens
what is a vaccination? -Answer--introduction of a vaccine containing appropriate
disease antigens into the body to induce artificial immunity
how do vaccines work? -Answer--- pathogen stimulaties wbc into making antigens
- dead or inactive pathogen enter body via injection
- antibodies stick to antigens and clump them together
- memory cells = immunity
what are the pros of immunisation? -Answer--- protected from certain diseases
- economic benefits
- eradicate diseases
- prevent epidemics
what are the cons of immunisation? -Answer--- chance of contracting diseases from
vaccine
- religions might be against it
- side effects
- only work for a certain amount of time
- antigenic variability
- certain pathogens hide from immune system
what is HIV -Answer--a retrovirus that attacks the body's immune system
what are the modes of transmission of HIV -Answer--- blood (transfusions)
- sharing needles
- breast feeding/ giving birth
- sex
what is herd immunity'? -Answer--vaccinating enough people so there isn't enough
hosts for the virus to spread
define 'epidemic' -Answer--infection of a country
