AQA A LEVEL BIOLOGY Questions With Accurate Answers
what are killer t-cells? - Accurate answers - cytotoxic cells
- bind to non-self antigens
how to killer t-cells work? - Accurate 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? - Accurate answers programmed cell death
how do killer t-cells destroy cancer? - Accurate 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? - Accurate answers creates holes in the cell membranes in order to
destroy the infected cell
what do helper t-cells do? - Accurate answers - produce cytokines
- cytokines stimulate b-cells to divide into plasma and memory cells
- activate killer t-cells
define helper t-cells - Accurate 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? - Accurate 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 - Accurate 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 - Accurate answers regulate the immune response by suppressing activity
of killer t-cells and b-cells
define 'microorganism' - Accurate answers organism that is too small to be seen without a
microscope
define 'pathogen' - Accurate answers microorganism that causes disease
outline phagocytosis - Accurate 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? - Accurate answers thymus gland
where do b-cells mature? - Accurate answers bone marrow
what do b-cells do? - Accurate answers - humoral response
- release antibodies
- complementary to a specific antigen
what response are plasma cells? - Accurate answers primary
what response are memory b-cells? - Accurate answers secondary
outline the humoral response - Accurate 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? - Accurate answers - forms clones of b-cells (plasma
and memory)
- clonal response
what do clones do? - Accurate answers each clone can produce one type of antibody (monoclonal)
which can be used in medicine
outline plasma cells - Accurate answers - primary response
- secrete antibodies
- only survive for a few day
- slow response = person gets ill before pathogen is killed
outline memory cells - Accurate answers - secondary response
- circulated in blood and tissue fluid
- divide rapidly
- rapid response so person doesn't get ill
what is an antibody? - Accurate answers y-shaped globular protein produced by b-cells
where are antibodies produced? - Accurate answers plasma b-cells
what are antibodies made of? - Accurate answers 4 polypeptide chains -- 2 heavy, 2 light
,what are the two regions an antigen is made of? - Accurate answers - variable
- constant
what is special about the variable region? - Accurate answers complementary and specific to an
antigen
what are the chains bonded by? - Accurate answers disulphide bridge
why do antibodies have a hinge region? - Accurate answers to allow the antibody to move to bind
to more than one antigen
what is 'monoclonal antibody production' - Accurate answers the process by which large quantities
of antibodies (targeted against a particular antigen) can be produced
how are monoclonal antibodies produced? - Accurate 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? - Accurate answers myeloma
what can be monoclonal antibodies be used as? - Accurate answers specific probe to track down
and purify specific protein that induced its transformation
what needs to happen to monoclonal antibodies before human use? - Accurate answers
humanisation
why do monoclonal antibodies need to be 'humanised' before used by humans? - Accurate answers
to stop the trigger of an immune response
what are monoclonal antibodies used for? - Accurate answers - pregnancy tests
- diagnostic tools for AIDS
- industrial production of interferon
what is a vaccine? - Accurate answers a dead or weakened version of a disease with relevant
antigens
what is a vaccination? - Accurate answers introduction of a vaccine containing appropriate disease
antigens into the body to induce artificial immunity
how do vaccines work? - Accurate 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? - Accurate answers - protected from certain diseases
- economic benefits
, - eradicate diseases
- prevent epidemics
what are the cons of immunisation? - Accurate 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 - Accurate answers a retrovirus that attacks the body's immune system
what are the modes of transmission of HIV - Accurate answers - blood (transfusions)
- sharing needles
- breast feeding/ giving birth
- sex
what is herd immunity'? - Accurate answers vaccinating enough people so there isn't enough hosts
for the virus to spread
define 'epidemic' - Accurate answers infection of a country
define 'endemic' - Accurate answers infection of a specific area
define 'pandemic' - Accurate answers infection of more than one country
give 2 types of natural immunity - Accurate answers - infection
- maternal antibodies
give 2 types of artificial immunity - Accurate answers - vaccine
- monoclonal antibodies
how does HIV result in the death of a t-cell? - Accurate answers - HIV recognises helper t-cell
- apoptosis
how might the global distribution of HIV/AIDS change in coming years? - Accurate answers - could
decrease due to potential cures and treatments being discovered
- could increase due to new strains
how does HIV replicate? - Accurate answers - virus fuses with cells plasma membrane
- reverse transcriptase synthesises dna to rna
- second strand is synthesised by reverse transcriptase to be complementary
- double strand is incorporated as provirus is cell's dna
- proviral gene transcribed into rna
- rna transcriped as mrna
- capsids assemble around viral genomes
- new viruses bud off from host cell
what are killer t-cells? - Accurate answers - cytotoxic cells
- bind to non-self antigens
how to killer t-cells work? - Accurate 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? - Accurate answers programmed cell death
how do killer t-cells destroy cancer? - Accurate 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? - Accurate answers creates holes in the cell membranes in order to
destroy the infected cell
what do helper t-cells do? - Accurate answers - produce cytokines
- cytokines stimulate b-cells to divide into plasma and memory cells
- activate killer t-cells
define helper t-cells - Accurate 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? - Accurate 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 - Accurate 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 - Accurate answers regulate the immune response by suppressing activity
of killer t-cells and b-cells
define 'microorganism' - Accurate answers organism that is too small to be seen without a
microscope
define 'pathogen' - Accurate answers microorganism that causes disease
outline phagocytosis - Accurate 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? - Accurate answers thymus gland
where do b-cells mature? - Accurate answers bone marrow
what do b-cells do? - Accurate answers - humoral response
- release antibodies
- complementary to a specific antigen
what response are plasma cells? - Accurate answers primary
what response are memory b-cells? - Accurate answers secondary
outline the humoral response - Accurate 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? - Accurate answers - forms clones of b-cells (plasma
and memory)
- clonal response
what do clones do? - Accurate answers each clone can produce one type of antibody (monoclonal)
which can be used in medicine
outline plasma cells - Accurate answers - primary response
- secrete antibodies
- only survive for a few day
- slow response = person gets ill before pathogen is killed
outline memory cells - Accurate answers - secondary response
- circulated in blood and tissue fluid
- divide rapidly
- rapid response so person doesn't get ill
what is an antibody? - Accurate answers y-shaped globular protein produced by b-cells
where are antibodies produced? - Accurate answers plasma b-cells
what are antibodies made of? - Accurate answers 4 polypeptide chains -- 2 heavy, 2 light
,what are the two regions an antigen is made of? - Accurate answers - variable
- constant
what is special about the variable region? - Accurate answers complementary and specific to an
antigen
what are the chains bonded by? - Accurate answers disulphide bridge
why do antibodies have a hinge region? - Accurate answers to allow the antibody to move to bind
to more than one antigen
what is 'monoclonal antibody production' - Accurate answers the process by which large quantities
of antibodies (targeted against a particular antigen) can be produced
how are monoclonal antibodies produced? - Accurate 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? - Accurate answers myeloma
what can be monoclonal antibodies be used as? - Accurate answers specific probe to track down
and purify specific protein that induced its transformation
what needs to happen to monoclonal antibodies before human use? - Accurate answers
humanisation
why do monoclonal antibodies need to be 'humanised' before used by humans? - Accurate answers
to stop the trigger of an immune response
what are monoclonal antibodies used for? - Accurate answers - pregnancy tests
- diagnostic tools for AIDS
- industrial production of interferon
what is a vaccine? - Accurate answers a dead or weakened version of a disease with relevant
antigens
what is a vaccination? - Accurate answers introduction of a vaccine containing appropriate disease
antigens into the body to induce artificial immunity
how do vaccines work? - Accurate 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? - Accurate answers - protected from certain diseases
- economic benefits
, - eradicate diseases
- prevent epidemics
what are the cons of immunisation? - Accurate 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 - Accurate answers a retrovirus that attacks the body's immune system
what are the modes of transmission of HIV - Accurate answers - blood (transfusions)
- sharing needles
- breast feeding/ giving birth
- sex
what is herd immunity'? - Accurate answers vaccinating enough people so there isn't enough hosts
for the virus to spread
define 'epidemic' - Accurate answers infection of a country
define 'endemic' - Accurate answers infection of a specific area
define 'pandemic' - Accurate answers infection of more than one country
give 2 types of natural immunity - Accurate answers - infection
- maternal antibodies
give 2 types of artificial immunity - Accurate answers - vaccine
- monoclonal antibodies
how does HIV result in the death of a t-cell? - Accurate answers - HIV recognises helper t-cell
- apoptosis
how might the global distribution of HIV/AIDS change in coming years? - Accurate answers - could
decrease due to potential cures and treatments being discovered
- could increase due to new strains
how does HIV replicate? - Accurate answers - virus fuses with cells plasma membrane
- reverse transcriptase synthesises dna to rna
- second strand is synthesised by reverse transcriptase to be complementary
- double strand is incorporated as provirus is cell's dna
- proviral gene transcribed into rna
- rna transcriped as mrna
- capsids assemble around viral genomes
- new viruses bud off from host cell
