AQA A Level Biology-LATEST UPDATE 2025 Edition – Practice
Questions and Model Answers Covering Full Spec-ALREADY
GRADED A+ | GUARANTEED PASS!!
what are killer t-cells? - (answers)- cytotoxic cells
- bind to non-self antigens
how to killer t-cells work? - (answers)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? - (answers)programmed cell death
how do killer t-cells destroy cancer? - (answers)- cancerous = mutations
- mutations = abnormal antigens
- killer t-cell binds to abnormal antigens
- killer t-cells induces death of cancerous cell
What does perforin do? - (answers)creates holes in the cell membranes in order to
destroy the infected cell
what do helper t-cells do? - (answers)- produce cytokines
- cytokines stimulate b-cells to divide into plasma and memory cells
- activate killer t-cells
define helper t-cells - (answers)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? - (answers)- 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 - (answers)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 - (answers)regulate the immune response by suppressing
activity of killer t-cells and b-cells
define 'microorganism' - (answers)organism that is too small to be seen without a
microscope
define 'pathogen' - (answers)microorganism that causes disease
,outline phagocytosis - (answers)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? - (answers)thymus gland
where do b-cells mature? - (answers)bone marrow
what do b-cells do? - (answers)- humoral response
- release antibodies
- complementary to a specific antigen
what response are plasma cells? - (answers)primary
what response are memory b-cells? - (answers)secondary
outline the humoral response - (answers)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? - (answers)- forms clones of b-cells (plasma
and memory)
- clonal response
what do clones do? - (answers)each clone can produce one type of antibody
(monoclonal) which can be used in medicine
outline plasma cells - (answers)- primary response
- secrete antibodies
- only survive for a few day
- slow response = person gets ill before pathogen is killed
outline memory cells - (answers)- secondary response
- circulated in blood and tissue fluid
- divide rapidly
- rapid response so person doesn't get ill
,what is an antibody? - (answers)y-shaped globular protein produced by b-cells
where are antibodies produced? - (answers)plasma b-cells
what are antibodies made of? - (answers)4 polypeptide chains -- 2 heavy, 2 light
what are the two regions an antigen is made of? - (answers)- variable
- constant
what is special about the variable region? - (answers)complementary and specific to an
antigen
what are the chains bonded by? - (answers)disulphide bridge
why do antibodies have a hinge region? - (answers)to allow the antibody to move to
bind to more than one antigen
what is 'monoclonal antibody production' - (answers)the process by which large
quantities of antibodies (targeted against a particular antigen) can be produced
how are monoclonal antibodies produced? - (answers)- 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? - (answers)myeloma
what can be monoclonal antibodies be used as? - (answers)specific probe to track
down and purify specific protein that induced its transformation
what needs to happen to monoclonal antibodies before human use? -
(answers)humanisation
why do monoclonal antibodies need to be 'humanised' before used by humans? -
(answers)to stop the trigger of an immune response
what are monoclonal antibodies used for? - (answers)- pregnancy tests
- diagnostic tools for AIDS
- industrial production of interferon
what is a vaccine? - (answers)a dead or weakened version of a disease with relevant
antigens
, what is a vaccination? - (answers)introduction of a vaccine containing appropriate
disease antigens into the body to induce artificial immunity
how do vaccines work? - (answers)- 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? - (answers)- protected from certain diseases
- economic benefits
- eradicate diseases
- prevent epidemics
what are the cons of immunisation? - (answers)- 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 - (answers)a retrovirus that attacks the body's immune system
what are the modes of transmission of HIV - (answers)- blood (transfusions)
- sharing needles
- breast feeding/ giving birth
- sex
what is herd immunity'? - (answers)vaccinating enough people so there isn't enough
hosts for the virus to spread
define 'epidemic' - (answers)infection of a country
define 'endemic' - (answers)infection of a specific area
define 'pandemic' - (answers)infection of more than one country
give 2 types of natural immunity - (answers)- infection
- maternal antibodies
give 2 types of artificial immunity - (answers)- vaccine
- monoclonal antibodies
how does HIV result in the death of a t-cell? - (answers)- HIV recognises helper t-cell
- apoptosis
Questions and Model Answers Covering Full Spec-ALREADY
GRADED A+ | GUARANTEED PASS!!
what are killer t-cells? - (answers)- cytotoxic cells
- bind to non-self antigens
how to killer t-cells work? - (answers)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? - (answers)programmed cell death
how do killer t-cells destroy cancer? - (answers)- cancerous = mutations
- mutations = abnormal antigens
- killer t-cell binds to abnormal antigens
- killer t-cells induces death of cancerous cell
What does perforin do? - (answers)creates holes in the cell membranes in order to
destroy the infected cell
what do helper t-cells do? - (answers)- produce cytokines
- cytokines stimulate b-cells to divide into plasma and memory cells
- activate killer t-cells
define helper t-cells - (answers)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? - (answers)- 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 - (answers)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 - (answers)regulate the immune response by suppressing
activity of killer t-cells and b-cells
define 'microorganism' - (answers)organism that is too small to be seen without a
microscope
define 'pathogen' - (answers)microorganism that causes disease
,outline phagocytosis - (answers)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? - (answers)thymus gland
where do b-cells mature? - (answers)bone marrow
what do b-cells do? - (answers)- humoral response
- release antibodies
- complementary to a specific antigen
what response are plasma cells? - (answers)primary
what response are memory b-cells? - (answers)secondary
outline the humoral response - (answers)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? - (answers)- forms clones of b-cells (plasma
and memory)
- clonal response
what do clones do? - (answers)each clone can produce one type of antibody
(monoclonal) which can be used in medicine
outline plasma cells - (answers)- primary response
- secrete antibodies
- only survive for a few day
- slow response = person gets ill before pathogen is killed
outline memory cells - (answers)- secondary response
- circulated in blood and tissue fluid
- divide rapidly
- rapid response so person doesn't get ill
,what is an antibody? - (answers)y-shaped globular protein produced by b-cells
where are antibodies produced? - (answers)plasma b-cells
what are antibodies made of? - (answers)4 polypeptide chains -- 2 heavy, 2 light
what are the two regions an antigen is made of? - (answers)- variable
- constant
what is special about the variable region? - (answers)complementary and specific to an
antigen
what are the chains bonded by? - (answers)disulphide bridge
why do antibodies have a hinge region? - (answers)to allow the antibody to move to
bind to more than one antigen
what is 'monoclonal antibody production' - (answers)the process by which large
quantities of antibodies (targeted against a particular antigen) can be produced
how are monoclonal antibodies produced? - (answers)- 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? - (answers)myeloma
what can be monoclonal antibodies be used as? - (answers)specific probe to track
down and purify specific protein that induced its transformation
what needs to happen to monoclonal antibodies before human use? -
(answers)humanisation
why do monoclonal antibodies need to be 'humanised' before used by humans? -
(answers)to stop the trigger of an immune response
what are monoclonal antibodies used for? - (answers)- pregnancy tests
- diagnostic tools for AIDS
- industrial production of interferon
what is a vaccine? - (answers)a dead or weakened version of a disease with relevant
antigens
, what is a vaccination? - (answers)introduction of a vaccine containing appropriate
disease antigens into the body to induce artificial immunity
how do vaccines work? - (answers)- 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? - (answers)- protected from certain diseases
- economic benefits
- eradicate diseases
- prevent epidemics
what are the cons of immunisation? - (answers)- 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 - (answers)a retrovirus that attacks the body's immune system
what are the modes of transmission of HIV - (answers)- blood (transfusions)
- sharing needles
- breast feeding/ giving birth
- sex
what is herd immunity'? - (answers)vaccinating enough people so there isn't enough
hosts for the virus to spread
define 'epidemic' - (answers)infection of a country
define 'endemic' - (answers)infection of a specific area
define 'pandemic' - (answers)infection of more than one country
give 2 types of natural immunity - (answers)- infection
- maternal antibodies
give 2 types of artificial immunity - (answers)- vaccine
- monoclonal antibodies
how does HIV result in the death of a t-cell? - (answers)- HIV recognises helper t-cell
- apoptosis
