10 questionsð¬ð§English
ð¡ïž The Immune Response â A-level
Biology · A-level â practise phagocytosis, T and B cells, antibodies, vaccination and primary vs secondary responses.
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Questions
Which of these best describes an antigen?
A molecule that triggers a specific immune response
A chemical released by T cells to kill infected cells
A protein made by plasma cells to bind pathogens
An enzyme that digests engulfed pathogens
20s
During phagocytosis, the vesicle containing the engulfed pathogen fuses with which organelle?
Lysosome
Mitochondrion
Golgi apparatus
Ribosome
20s
Which cells secrete antibodies into the blood?
Cytotoxic T cells
Memory cells
T helper cells
Plasma cells
20s
What makes each type of antibody specific to just one antigen?
The number of disulfide bridges in the molecule
A unique amino acid sequence in the variable region
A unique amino acid sequence in the constant region
The number of polypeptide chains in the molecule
30s
How do cytotoxic T cells kill body cells infected by a virus?
They engulf the infected cells by phagocytosis
They release lysozyme, which digests the cell wall
They release perforin, which makes holes in the membrane
They release antibodies that clump the cells together
30s
Why is the secondary immune response faster than the primary response?
Antibodies from the first infection stay at high levels
Memory cells quickly divide to form plasma cells
Phagocytes remember the antigen from the first infection
The pathogen is weaker when it infects a second time
30s
Which of these is an example of passive immunity?
Receiving a vaccine containing an attenuated virus
Having a booster injection of tetanus toxoid
Antibodies crossing the placenta from mother to fetus
Recovering from a chickenpox infection
30s
How does vaccinating a large proportion of a population protect people who are not vaccinated?
The pathogen mutates into a harmless form
Fewer people carry the pathogen, so contact is less likely
Vaccinated people pass antibodies on to others
Vaccinated people pass memory cells on to others
30s
HIV infects and destroys T helper cells. Why does this eventually lead to AIDS?
B cells and cytotoxic T cells are no longer activated
HIV antibodies start to destroy red blood cells
Plasma cells begin to make antibodies against self
Phagocytes can no longer engulf any pathogens
30s
In an indirect ELISA test, why must the well be washed after adding the enzyme-linked second antibody?
To remove the antigen that is bound to the well
To activate the enzyme attached to the second antibody
To denature the enzyme before the substrate is added
To remove unbound antibody that could give a false positive
30s