AQA A Level Biology Paper 1 WITH CORRECT AND
VERIFIABLE ANSWERS 100% YEAR 2024/2025
what are killer t-cells? - verified answers-- cytotoxic cells
- bind to non-self antigens
how do killer t-cells work? - verified 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? - verified answers-programmed cell death
how do killer t-cells destroy cancer? - verified 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? - verified answers-creates holes in the
cell membranes in order to destroy the infected cell
what do helper t-cells do? - verified answers-- produce
cytokines
- cytokines stimulate b-cells to divide into plasma and memory
cells
- activate killer t-cells
define helper t-cells - verified 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? - verified 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 - verified 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 - verified answers-regulate the
immune response by suppressing activity of killer t-cells and b-
cells
define 'microorganism' - verified answers-organism that is too
small to be seen without a microscope
define 'pathogen' - verified answers-microorganism that causes
disease
outline phagocytosis - verified 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? - verified answers-thymus gland
where do b-cells mature? - verified answers-bone marrow
what do b-cells do? - verified answers-- humoral response
- release antibodies
- complementary to a specific antigen
,what response are plasma cells? - verified answers-primary
what response are memory b-cells? - verified answers-
secondary
outline the humoral response - verified 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? - verified answers--
forms clones of b-cells (plasma and memory)
- clonal response
what do clones do? - verified answers-each clone can produce
one type of antibody (monoclonal) which can be used in
medicine
outline plasma cells - verified answers-- primary response
- secrete antibodies
- only survive for a few day
- slow response = person gets ill before pathogen is killed
outline memory cells - verified answers-- secondary response
- circulated in blood and tissue fluid
- divide rapidly
- rapid response so person doesn't get ill
what is an antibody? - verified answers-y-shaped globular
protein produced by b-cells
where are antibodies produced? - verified answers-plasma b-
cells
, what are antibodies made of? - verified answers-4 polypeptide
chains -- 2 heavy, 2 light
what are the two regions an antigen is made of? - verified
answers-- variable
- constant
what is special about the variable region? - verified answers-
complementary and specific to an antigen
what are the chains bonded by? - verified answers-disulphide
bridge
why do antibodies have a hinge region? - verified answers-to
allow the antibody to move to bind to more than one antigen
what is 'monoclonal antibody production' - verified answers-the
process by which large quantities of antibodies (targeted
against a particular antigen) can be produced
how are monoclonal antibodies produced? - verified 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? - verified answers-
myeloma
what can be monoclonal antibodies be used as? - verified
answers-specific probe to track down and purify specific protein
that induced its transformation
what needs to happen to monoclonal antibodies before human
use? - verified answers-humanisation
VERIFIABLE ANSWERS 100% YEAR 2024/2025
what are killer t-cells? - verified answers-- cytotoxic cells
- bind to non-self antigens
how do killer t-cells work? - verified 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? - verified answers-programmed cell death
how do killer t-cells destroy cancer? - verified 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? - verified answers-creates holes in the
cell membranes in order to destroy the infected cell
what do helper t-cells do? - verified answers-- produce
cytokines
- cytokines stimulate b-cells to divide into plasma and memory
cells
- activate killer t-cells
define helper t-cells - verified 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? - verified 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 - verified 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 - verified answers-regulate the
immune response by suppressing activity of killer t-cells and b-
cells
define 'microorganism' - verified answers-organism that is too
small to be seen without a microscope
define 'pathogen' - verified answers-microorganism that causes
disease
outline phagocytosis - verified 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? - verified answers-thymus gland
where do b-cells mature? - verified answers-bone marrow
what do b-cells do? - verified answers-- humoral response
- release antibodies
- complementary to a specific antigen
,what response are plasma cells? - verified answers-primary
what response are memory b-cells? - verified answers-
secondary
outline the humoral response - verified 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? - verified answers--
forms clones of b-cells (plasma and memory)
- clonal response
what do clones do? - verified answers-each clone can produce
one type of antibody (monoclonal) which can be used in
medicine
outline plasma cells - verified answers-- primary response
- secrete antibodies
- only survive for a few day
- slow response = person gets ill before pathogen is killed
outline memory cells - verified answers-- secondary response
- circulated in blood and tissue fluid
- divide rapidly
- rapid response so person doesn't get ill
what is an antibody? - verified answers-y-shaped globular
protein produced by b-cells
where are antibodies produced? - verified answers-plasma b-
cells
, what are antibodies made of? - verified answers-4 polypeptide
chains -- 2 heavy, 2 light
what are the two regions an antigen is made of? - verified
answers-- variable
- constant
what is special about the variable region? - verified answers-
complementary and specific to an antigen
what are the chains bonded by? - verified answers-disulphide
bridge
why do antibodies have a hinge region? - verified answers-to
allow the antibody to move to bind to more than one antigen
what is 'monoclonal antibody production' - verified answers-the
process by which large quantities of antibodies (targeted
against a particular antigen) can be produced
how are monoclonal antibodies produced? - verified 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? - verified answers-
myeloma
what can be monoclonal antibodies be used as? - verified
answers-specific probe to track down and purify specific protein
that induced its transformation
what needs to happen to monoclonal antibodies before human
use? - verified answers-humanisation
