Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > Topic 2C: Cells and the Immune System > Flashcards

Topic 2C: Cells and the Immune System Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is a pathogen? [1]

A

A microorganism (e.g. bacteria, fungi, protists) or viruses that cause infectious disease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a toxin?

A

A poisonous substance produced by living organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is an antigen?

A

A foreign molecule (usually a protein) that stimulates an immune response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When a pathogen enters the body it may be destroyed by phagocytosis.
Describe how. [4]

A
  1. Phagocyte attracted by a substance / recognises (foreign) antigen;
  2. (Pathogen) engulfed;
  3. Enclosed in vesicle/phagosome;
  4. (Phagosome) fuses with lysosome;
  5. Lysosome contains lysozymes;
  6. Pathogen digested (by lysozymes).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is an antibody?

A

A protein capable of binding a specific antigen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why do antibodies have a quaternary structure? [1]

A
  1. More than one / four polypeptide chains
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Explain why an antibody binds to a specific antigen. [3]

A
  1. Antibody / variable region has specific amino acid sequence / primary structure;
  2. The shape / tertiary structure of the binding site is complementary to / binds with these antigens;
  3. Forms complex between antigen and antibody.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe how a phagocyte destroys a pathogen present in the blood. [3]

A
  1. Engulfs;
  2. Forming phagosome and fuses with lysosome;
  3. Enzymes digest.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

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

A
  1. (Cells from) other organisms/transplant;
  2. Abnormal/cancer/tumour (cells);
  3. (Cells) infected by virus.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the role of disulphide bridges in forming the quaternary structure of an antibody? [1]

A
  1. Joins (different) polypeptides
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe how phagocytosis of a virus leads to presentation of its antigens. [3]

A
  1. Phagosome fuses with lysosome;
  2. (Virus) destroyed by lysozymes;
  3. Antigen (from virus) displayed in the cell membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe how presentation of a virus antigen leads to the secretion of an antibody against this virus antigen. [3]

A
  1. Helper T cell binds to the antigen (on the antigen-presenting cell/phagocyte);
  2. This helper T cell stimulates a specific B cell;
  3. B cell divides by mitosis;
  4. (Forms) plasma cells that release antibodies.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are monoclonal antibodies? [1]

A

Antibodies with the same tertiary structure produced from a genetically identical set of plasma cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is immunity achieved?

A

Through the presence of antibodies against the antigens of that pathogen in a person’s body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does a vaccine make someone immune to a pathogen? [5]

A
  1. (Vaccine contains) antigen / attenuated/dead/inactive pathogen;
  2. (Specific) helper T cell stimulates B cell specific to antigen;
  3. B cell clones/divides by mitosis;
  4. Plasma cells release antibodies;
  5. Memory cells produced meaning higher concentration of antibodies/antibodies produced faster in secondary response/on infection with the actual pathogen.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is herd immunity?

A

A form of indirect protection from infectious disease that occurs when a sufficient percentage of a population has become immune to an infection, reducing the likelihood of infection spreading to individuals who lack immunity.

17
Q

Describe how B lymphocytes would respond to a vaccination against a virus.

Do not include details of the cellular response in your answer. [3]

A
  1. B cell binds to specific/complementary (viral) antigen;
  2. B cell divides by mitosis;
  3. (B cells develop into) plasma cells that release antibodies (against the virus);
  4. (B cells develop into) memory cells
18
Q

What is an allergic reaction?

A

An immune response to an otherwise harmless substance.

19
Q

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

A
  1. (Antivenom) antibodies bind to the toxin/venom/antigen and (causes) its destruction;
  2. Active immunity would be too slow.
20
Q

When making an antivenom, a mixture of venoms from several snakes of the same species is used.

Suggest why. [2]

A
  1. May be different form of antigen/toxin (within one species);
  2. Different antibodies (needed in the antivenom)
21
Q

During the production of antivenom, the animals used are under ongoing observation by a vet.

Suggest one reason why. [1]

A
  1. (So) the animal does not suffer from the venom/vaccine/toxine;
  2. (So) the animal does not suffer anaemia/does not suffer as a result of blood collection;
  3. (So) the animal does not have pathogen that could be transferred to humans.
22
Q

During vaccination, each animal is initially injected with a small volume of venom. Two weeks later, it is injected with a large volume of venom.

Use your knowledge of the hum oral immune response to explain this vaccination programme. [3]

A
  1. B cells specific to the venom reproduce by mitosis;
  2. (B cells produce) plasma cells and memory cells;
  3. The second dose produces antibodies (in secondary immune response) in higher concentration and quickly
23
Q

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]

A
  1. (Anti-AQP4) antibody has a (specific) tertiary structure;
  2. Has binding site / variable region that only binds/complementary to one antigen;
  3. Antigen to this antibody (only) found in these nerve cells;
  4. So, antibody (only) binds to / forms antigen-antibody complex with these nerve cells (causing damage).
24
Q

Describe the structure of the human immunodeficiency virus (HIV). [4]

A
  1. RNA (as genetic material);
  2. Reverse transcriptase;
  3. (Protein) capsid;
  4. Phospholipid viral envelope;
  5. Attachment proteins
25
Q

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

A
  1. RNA converted into DNA using reverse transcriptase;
  2. DNA inserted into DNA;
  3. DNA transcribed into (HIV m)RNA;
  4. (HIV mRNA) translated into viral proteins (for assemble into viral particles)
26
Q

The ELISA test only detects the presence of HIV antibodies. Give two reasons why it cannot be used to find out if a person has AIDS. [2]

A

(To diagnose AIDS, need to look for)
1. (AIDS-related) symptoms;
2. Number of helper T cells

27
Q

In the ELISA test, the solution will remain yellow if a person is not infected with HIV. Explain why. [2]

A
  1. HIV antibody is not present;
  2. (So) second antibody/enzyme will not binds / is not present
28
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
  1. Children receive antibodies from their mothers;
  2. (So) solution will always test positive
29
Q

Describe the role of antibodies in producing a positive result in an ELISA test. [4]

A
  1. (First) antibody binds to antigen;
  2. (Second) antibody with enzyme attached is added;
  3. (Second) antibody attaches to antigen;
  4. (Substrate added) and colour change
30
Q

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

A
  1. (HIV is) invading cells which make new viruses;
  2. Cells release viruses into blood
31
Q

Explain why the number of HIV particles in the blood can remain low for many years after infection. [1]

A
  1. Virus remains dormant/exists as DNA in host DNA
32
Q

Describe how HIV is replicated after it has entered a human cell. [4]

A
  1. Reverse transcriptase;
  2. Enzyme uses (HIV) RNA to make DNA (copy);
  3. DNA joined to (host) cell’s DNA;
  4. DNA used to make HIV RNA (copies);
  5. And HIV capsid proteins;
  6. Made at (host) ribosomes;
  7. Assembly of new virus particles;
  8. Budding off from membrane (of host cell)
33
Q

The destruction of T-cells by HIV leads to death of an infected person.
Explain how. [2]

A
  1. Not enough T-cells to activate B-cells;
  2. Person unable to fight infections/cancer
34
Q

What is an antigen? [2]

A
  1. Molecule/protein;
  2. Stimulates immune response;
  3. (That causes) production of antibodies
35
Q

Explain why antibodies against Salmonella do not normally bind to HIV. [2]

A
  1. Antigens on HIV are different shape;
  2. So antibody not complementary to antigen;
  3. Receptor sites on antibody specific to one antigen
36
Q

HIV infects some human cells, such as T-cells, but not others.
Suggest why. [2]

A
  1. HIV binds to specific receptor;
  2. Only present on certain cells
37
Q

Antibiotics are not used to treat viral infections, such as HIV.
Explain why. [2]

A
  1. Antibiotics stop metabolism, viruses don’t have metabolism;
  2. Viruses hide in cells, antibiotics can’t reach

Biology (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions