Immunity Questions Flashcards
A test strip that uses monoclonal antibodies can be used to determine whether a person is infected by Plasmodium. It can also determine which species they are infected by.
- a sample of the persons blood is mixed with antibody A solution that binds to a protein found in both species of Plasmodium. This antibody has a coloured dye attached.
- a test strip is put into the mixture. The moisture moves up the strip by capillary action to absorbant pad.
- three other antibodies B, C, D, are attached to test strip. D is at the bottom of strip and binds only to Plasmodium Falciparum, C is in the middle and binds to Plasmodium Vivax, B is at the top and binds to antibody A.
A) Explain why antibody A attaches only to the protein found in species of Plasmodium. (2)
B) antibody B is important if this test shows a person is not infected with Plasmodium.
Explain why antibody B is important.(2)
C) image of test strip: bottom line isn’t dyed, middle line is dyed, top line is dyed.
What can you conclude from this result.
Explain how you reached your conclusion. (4)
A) -antibody A is complementary to binding site on protein
-antibody has specific tertiary structure
B) -prevent false negative
-shows antibody a has moved up the strip and not bound to any protein
C) -this person is infected with plasmodium vivax
-coloured dye where antibody C is present
-C only binds protein from vivax
-D isnt coloured so no falciparum
When a vaccine is given to a person, it leads to the production of antibodies against a disease-causing organism. Describe how. (5)
-a vaccine contains antigens from a specific pathogen
-macrophage presents antigen on its surface
-T-cell with complementary receptor protein bonds to antigen
-T-cell stimulates B cell with complementary antibody on it surface
-B cell secretes large amounts of antibody
-B cell divides to form clones all producing same antibody
Describe the difference between active and passive immunity. (5)
ACTIVE:
-production of antibody by plasma cells
-takes time to develop
-memory cells produced in response to antigen
-provide long term immunity
PASSIVE:
-antibody introduced to body from outside
-fast acting
-no memory cells produced as antibody is broken down so short term immunity
What is an antigen? (2)
- foreign protein
- that stimulates an immune response
What is an antibody? (2)
- protein specific to antigen
- produced by B cells and secreted by plasma cells
Graph:
1. Two weeks before first vaccine, no antibody’s in blood
2. Two weeks after first dose of vaccine, little antibody’s in blood
3. Two weeks after second dose of vaccine, lots of antibody’s in blood
Explain the differences between mean conc of antibody’s in blood samples 1,2 and 3. (4)
1= -before vaccination
-no antibody’s released as patient not encountered virus
2= -primary response
-clonal selection of B cells into plasma cells
-plasma cells release antibodies
3= -secondary response
-memory cells produces more antibodies rapidly
Scientists measured the absorption of each sample of blood plasma using a colorimeter. They used a calibration curve to find the conc of protein in samples of blood plasma.
Describe how the scientists could obtain data to produce a calibration curve and how they would use the calibration curve to find the conc of protein in a sample of blood plasma. (3)
- produce known conc of protein
-measure absorbance of each conc with colorimeter
-plot graph of absorbance of Y-axis against conc on X-axis and draw curve
-use absorbance of sample to find protein conc from curve
Older people are more likely to suffer from infectious diseases.
Suggest how this may be linked to the deacrease in the mean conc of protein in the blood as people get older. (1)
-fewer antibodies
NMO is a disease that leads to damage to nerve cells in the spinal cord. A person with NMO produces anti-AQP4 antibody that attacks only these nerve cells.
Explain why the anti-AQP4 antibody only damages these cells. (4)
- antibody’s have specific tertiary structure that complementary to one specific antigen
-antigen to this antibody only found on these nerve cells in spinal cord - form antigen-antibody complex
A new treatment for NMO involves using a monoclonal antibody. The structure of the new variable region of this monoclonal antibody is identical to the variable region of an anti-AQP4 antibody, but the rest of its structure is different.
Use this info and your knowledge of antigen-antibody complexes to suggest how this monoclonal antibody prevents anti-AQP4 damaging nerve cells. (2)
-monoclonal antibodies will bind to nerve cell antigens, preventing anti-AQP4 from binding
-when monoclonal antibodies bind it doesn’t cause damage to nerve cell
What is a monoclonal antibody? (1)
- antibodies with the same tertiary structure
After a disease is diagnosed, monoclonal antibodies are used in some medical treatments.
Give one example of using monoclonal antibodies in a medical treatments. (1)
-targets cancer cells
Describe the role of antibodies in producing a positive result in an ELISA test. (4)
- first set on antibodies bind to complementary antigen
- second set of antibodies with enzymes attached to them are added
- second antibody attaches to antigen
- solution added and colour changes
Describe and explain the role of antibodies in stimulating phagocytosis.
Do not include details about the process of phagocytosis. (2)
- bind to antigen
- antibody’s cause agglutination (clumping)
- attracts phagocytes
Figure 4= table showing 3 separate MenG injections and then 60, 120 and 180 days after 3rd injection and the effect of all this on concentration of anti-meningitis antibody. A dotted line across the graph shows the minimum portective antibody conc. at 1st injection 2 crosses are above/on the line and 7 are below, at 2nd 6 are above/on line and one below, at 3rd all are above. After 60 days crosses have moved down towards line, at 120 days only one is still above line, at 180 days all are below line.
Using figure 4 what can you conclude about the effectiveness of each injection on the immune response of these mice? (4)
- the injections increased the mean conc of anti-meningitis antibody in mice
-1st injection protects some mice and causes primary immune response
-2nd and 3rd protects all mice and causes secondary response- 2nd and 3rd uses memory cells
-this is because antibody conc above protective level
-antibody conc decreased rapidly after 3rd
-no mice protected after 180 days so vaccine not effective in the long run
Figure 4= table showing 3 separate MenG injections and then 60, 120 and 180 days after 3rd injection and the effect of all this on concentration of anti-meningitis antibody. A dotted line across the graph shows the minimum portective antibody conc. at 1st injection 2 crosses are above/on the line and 7 are below, at 2nd 6 are above/on line and one below, at 3rd all are above. After 60 days crosses have moved down towards line, at 120 days only one is still above line, at 180 days all are below line.
The scientists hypothesised that memory B cells had formed in the mice 180 days after 3rd injection.
Suggest and explain a practical method the scientists could use to test the hypothesis. (2)
-inject vaccine again
-memory cells present if immune response is quicker then 1st injection and symptoms dont develop
-add enzymes attached to second antibody against memory cells
-colour change shows memory cell present
Describe how a phagocyte destroys a pathogen present in the blood. (2)
- engulfs pathogen
-forming a vesicle/ phagosome and enfuses with lysosome
-enzyme hydrolyses microbes
Give two types of cell other than pathogens that can stimulate an immune response. (2)
- cancer cell
- cells infected by virus
What is the role in a disulfide bridge in forming the quaternary structure of an antibody? (1)
- it joins together 2 polypeptides
Explain how HIV affects the production of antibodies when AIDS develops in a person? (3)
Describe how HIV is replicated. (4)
- attachment protein binds to CD4 protein on helper t-cell
- RNA and reverse transcriptase enter t-cell
- reverse transcriptase converts virus RNA to DNA, making viral mRNA
-new viral proteins are assembled and released
Describe and explain two ways that microvilli in the cell lining of the ileum increase the rate of absorption by the cell. (2)
-SA of microvilli increases diffusion or
-mircrovilli increase SA for more channel/carrier proteins
-many mitochondria release energy
The protein ZO-1 is found on the surface of ileum cells.
A scientist used anti-ZO-1 monoclonal antibody to identify ileum cells in a sample of intestine observed using an optical microscope.
Suggest how the monoclonal antibody helped the scientist to identify ileum cells in the sample of intestine. (3)
-ZO-1 is located on cell-surface membrane
-antibody’s are complementary to ZO-1 antigens
-anti-ZO-1 would attach to all protein
-introduce dye and you can easily locate the ileum cells using a mircroscope
Describe one difference between the structure of DNA in a prokaryotic cell and in a eukaryotic cell. (1)
- prokaryotes have circular DNA not linear
Streptococcus bacteria can infect the lungs when air is breathed in and cause lung disease.
Describe the mechanism of breathing that causes air to enter lungs. (3)
-diaphragm muscles contract and diaphragm flattens
-external intercostal muscles contract and ribcage pulled up/out
-causes vol increase and pressure decrease in thoracic cavity
Some strains of streptococcus bacteria are more likely to cause lung disease than other strains.
Strains that do not cause lung disease are quickly destroyed by phagocytes. Phagocytes are stimulated when they bind to mure in on streptococcus bacteria.
Each strain of streptococcus bacteria has a capsule of different thickness from the others.
Suggest how streptococcus bacteria with a thicker capsule are more likely to survive and so cause lung disease. (2)
-thicker capsule so phagocytes less likely to bind to murein cell wall
-reduced phagocytosis so more bacterial growth/ binary fission
