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Biology P1 > Unit 2- Immunity =) > Flashcards

Unit 2- Immunity =) Flashcards

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1
Q

Older people are more likely to suffer from infectious diseases.
Sugest how this may be linked to the decrease in the mean concentration of protein in the blood as people get older. (1)

A

↓ antibodies

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2
Q

If a sheep is injected with the box jellyfish venom on more than one occasion a higher yield of antivenom is obtained.
Explain why. (2)

A
  • stimulates prod of memory cells
  • secondary response
  • quicker antibody prod
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3
Q

Injecting antivenom does not give a person lasting protection against the venom of box jellyfish.
Explain why. (2)

A
  • passive immunity
  • x memory cells produced
  • antivenom breaks down (after treatment)
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4
Q

Suggest one possible problem in injecting people with antivenom made in sheep. (1)

A
  • antibodies from an animal would trigger an immune response
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5
Q

Describe how a phagocyte destroys a pathogen present in the blood. (3)

A
  • attracted by/ recognises antigen
  • engulfs
  • enclosed in vesicle + fuses w/ lysosome
  • hydrolysed by enzymes
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6
Q

What is the role of the disulfide bridge in forming the quaternary structure of an antibody? (1)

A

Joins 2 polypeptides

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7
Q

In Europe, viruses have infected a large number of frogs of different species. The viruses are closely related and all belong to the Ranavirus group.
Previously, the viruses infected only one species of frog.
Suggest and explain how the viruses became able to infect other species of frog. (2)

A
  • mutation in viral DNA
  • tertairy structure of attachment protein changed
  • ✔️ bind to recptors of other species
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8
Q

Determining the genome of the viruses could allow scientists to develop a vaccine.
Explain how. (2)

A
  • ✔️ identify proteins from genetic code
  • ✔️ identify potential antigens
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9
Q

Describe how the B lymphocytes of a frog would respond to vaccination against Ranavirus.
You can assume that the B lymphocytes of a frog respond in the same way as B lymphocytes of a human. (3)

A
  • B cells bind to complementary antigen
  • divide by mitosis
  • Plasma cells produce antibodies
  • memory cells
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10
Q

Describe how the human immunodeficiency virus (HIV) is replicated once inside helper T cells (TH cells). (4)

A
  • RNA converted into DNA by reverse transcriptase
  • DNA incorporated into TH cell’s DNA in nucleus
  • transcribed into HIV mRNA
  • translated into new HIV proteins
  • assembled into viral particles
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11
Q

Explain how HIV affects the production of antibodies when AIDS develops in a person. (3)

A
  • ❌antibodies produced
  • ∵ HIV destroys TH cells
  • ❌stimulate B-cells –>❌divide by mitosis to produce plasma cells
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11
Q

Describe and explain the role of antibodies in stimulating phagocytosis.
Do not include details about the process of phagocytosis. (2)

A
  • bind to antigens
  • agglutination
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12
Q

Explain how the treatment with antivenom works and why it is essential to use passive immunity, rather than active immunity. (2)

A
  • antibodies destroy antigens by binding
  • active- too slow
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13
Q

A mixture of venoms from several snakes of the same species is used to produce antivenom.
Suggest why. (2)

A
  • snakes within one species may have diff. forms of antigen
  • diff. antibodies (so complementary to several antigens)
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14
Q

During vaccination, each animal is initially injected with a small volume of venom. Two weeks later, it is injected with a larger volume of venom.
Use your knowledge of the humoral immune response to explain this
vaccination programme. (3)

A
  • B cells specific to venom- divide by mitosis
  • produce plama cells + memory cells
  • 2nd dose stimulates faster antibody production + in ↑ conc.
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15
Q

Azidothymidine (AZT) is a drug used to treat people infected with human immunodeficiency virus (HIV). It inhibits the enzyme that synthesises
DNA from HIV RNA.
Suggest why this does not destroy HIV in the body but stops or slows the development of AIDS. (4)

A
  • infected person already has HIV DNA in their DNA
  • new HIV still made
  • reverse transcriptase inhibited
  • stops new HIV from forming new HIV DNA
  • stops destruction of ↑ infected T cells
  • immune system can still work (∴ AIDS ❌develop)
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16
Q

Give two ways in which pathogens can cause disease. (2)

A
  • release toxins
  • kill cells
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17
Q

Honey contains a high concentration of
sugar.
Use your knowledge of water potential to suggest how putting honey on a cut kills
bacteria. (3)

A
  • Ψ in bacterial cells > honey
  • leaves cells by osmosis
  • metabolic reactions stop–> dies
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18
Q

What is an antigen? (2)

A
  • foreign protein
  • stimulates an immune response
19
Q

What is an antibody? (2)

A
  • protein specific to an antigen
  • produced by B cells
20
Q

Describe how vaccination can lead to protection against bacterial meningitis. (6)

A
  1. antigens on surface of bacterium bind to surface receptors on specific B cell
  2. B cells divide by mitosis to produce plasma cells
  3. ∵ stimulated by T cells
  4. plasma cells release antibodies
  5. some B cells form memory cells
  6. produce (↑) antibodies + quicker
21
Q

When a vaccine is given to a person, it leads to the production of antibodies against a disease-causing organism.
Describe how.
(5)

A
  1. vaccine contains antigen of pathogen
  2. macrophage present antigens on its surface
  3. T cells w/ complementary receptor protein binds to antigen
  4. stimulates B cells
  5. w/ complementary antibody on its surface
  6. releases large amounts of antibody
  7. B cell divides to form clones- all producing same antibody
22
Q

Explain why the number of HIV particles in blood rises during the first few months after infection. (2)

A
  • HIV invading cells–> make new HIV particles
  • cells release viruses into blood
23
Q

Explain why the number of HIV particles in the blood remains low between 1 and 7 years after infection. (1)

A
  • virus remains dormant (exists as DNA in host DNA)
24
Q

A person developed a large number of infections about 9 years after he first becaome infected with HIV.
Explain why. (4)

A
  1. HIV destroys T-cells
  2. ↑ viruses produced ∴ ↓ T-cells
  3. ↓ T-cells activate B-cells
  4. ↓ antibody prod.
  5. compromised immune system–> inability to fight infections
  6. opportunistic infections
25
Q

What is an attenuated microorganism? (2)

A
  • alive
  • but x cause symptoms of disease (avirulent)
26
Q

It took more than a week for antibodies to appear in the child’s blood after the first vaccination.
Explain why. (2)

A

Takes time for:
1. antigens to be recognised
2. T-cells to be activated
3. B-cells to be activated/ plasma cells to release antibodies

27
Q

Explain why this ELISA test would detect vCJD protein, but not other antigens in the urine. (2)

A
  • antibodies are specific
  • other antigens diff. shape –> x bind to antibodies
28
Q

Explain why the antibodies used in an ELISA test must be monoclonal antibodies. (1)

A
  • all have same shape
  • only bind to specific antigen
29
Q

Why is it important to wash the plate after a second antibody is added in an ELISA test? (2)

A
  • second antibody would remain
  • enzyme still react w/ substrate when x antigens present
30
Q

When a pathogen causes an infection, plasma cells secrete sntibodies which destroy this pathogen.
Explain why these antibodies are only effective agasint a specific pathogen. (2)

A
  • antibodies- specific TERTIARY STRUCTURE
  • complementary to antigen (bind –> antibody-antigen complex)
31
Q

Ebola is a rare disease in humans, passed onto humans from wild animals.
Suggest, using your knowledge of the immune system, why the disease spreads faster once it is presnt in one human in an urban area. (4)

dk if it’s a real one

A
  1. rare- x prev. immunity
  2. takes time to recognise antigen, clone B cells, release antibodies
  3. infectious while immune system still fighting pathogen
  4. contagious- eg. contact w/ body fluids/ contaminated clothing
32
Q

The vaccine is made from HPV types 16 and 18.
Explain why this vaccine may not protect against other types of this virus. (2)

A
  1. diff. antigens
  2. x memory cells for those antigens
  3. antibodies x bind
33
Q

3 injections of the HPV vaccine are given.
Suggest why. (2)

A
  • ↑ antigens
  • ↑ memory cells
  • ↑ + quicker antibodies
34
Q

People given whole-cell vaccines produced a greater range of antibodies against the bacterium than the people given the vaccines containing parts of the bacterial cells.
Explain why. (2)

A
  • many diff. antigens
  • each antigen stimulates its own immune response
35
Q

The scientists concluded from their test that 4% of patients with long-term coughs actually had whooping cough.
Explain how they used the results of their test to reach this conclusion. (3)

A
  • only patient who had whooping cough have toxins
  • toxin = antigen only prodiced by this bacterium
  • ∴ presence of specific antibody
36
Q

What is a monoclonal antibody? (1)

A
  • antibodies produced from identical plasma cells
  • w/ same tertiary structure
37
Q

After a disease is diagnosed, monoclonal antibodies are used in some medical treatments.
Give one example of using monoclonal antibodies in a medical treatment. (1)

A
  • targets specific cells
  • block antigens on cells
38
Q

Describe the role of antibodies in producing a positive result in an ELISA test. (4)

A
  1. 1st antibody binds to comp. antiigen
  2. 2nd antibody added- w/ enzyme attached
  3. 2nd antibody attaches to antigen
  4. colourless substrate added –> colour changed
39
Q

Give two factors, other than cost, that should be considered when selecting an antibiotic to treat a bacterial disease. (2)

A
  1. side effects/ toxicity to cells
  2. interaction w/ other drugs
  3. how much resistance the bacteria have built up
  4. should only act on problem bacteria
40
Q

Suggest how one antibody can be specific to tick protein and to alpha-gel. (2)

A
  • similar shape
  • antibody complimentary to both
41
Q

Give two types of cell, other than pathogens, that can stimulate an immune response. (2)

A
  1. cells from other organisms
  2. tumour/ abnormal cells
  3. cells infected by virus
42
Q

In Europe, viruses have infected a large number of frogs of different species. The viruses are closely related and all belong to the Ranavirus group.
Previously, the viruses infected only one species of frog.
Suggest and explain how the viruses became able to infect other species
of frog. (2)

A
  • mutation in viral DNA
  • altered 3’ struc of viral attachment protein
  • ✔ bind to receptors of other species
43
Q

Stem cell growth factor receptor protein (SCFR) is on the surface membrane of a stem cell.
After it has differentiated, SCFR is enclosed within a vesicle and destroyed by a lysosome.
Suggest how SCFR is destroyed by a lysosome. (2)

A
  1. vesicle fuses w/ lysosome
  2. lysosome hydrolyses SCFRA
44
Q

Give two types of cell that can stimulate an immune response. (2)

A
  1. pathogens
  2. abnormal body cells
  3. cells from an individual of same species
  4. antigen-presenting cell

    • x dead/ damaged!
45
Q

As humans age, there is a decrease in body protein.
Give the name of one body protein that could have resulted in reduced immunity. (1)

A

antibodies

46
Q

A mother who was infected with HIV gave birth to a baby. The baby tested positive using this test. This does not prove the baby is infected with HIV.
Explain why. (2)

A
  • received from mother
  • solution will always turn blue (before 18 months)

Biology P1 (34 decks)

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