Topic 2C- Cells and the immune system - RANDOM QUESTIONS

Question 1

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

Answer 1

1. Helper T cell binds to the antigen.
2. This helper t cell stimulates a specific B cell.
3. B cell clones
4. Forms plasma cells that release antibodies.

Question 2

Give 2 ways in which pathogens can cause disease.

Answer 2

1. Release toxins
2. Destroy host cells, direct cellular attack.

Question 3

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

Answer 3

Inside the bacteria will have a high water potential. Water will move out into the honey by osmosis which has lots of sugar molecules with low water potential. The bacteria will shrivel up and die due to the water moving out of it.

Question 4

Describe how a phagocyte destroys a pathogen present in the blood.

Answer 4

1. Engulf the pathogen
2. Form vesicle (phagosome), fuse with lysosome.
3. Enzyme hydrolysis

Question 5

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

Answer 5

1. Cell from transplant organ
2. Tumour cell

Question 6

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

Answer 6

Hold and join the polypeptide.

Question 7

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

Answer 7

1. Phagosome/ vesicle fuses with lysosome.
2. Virus destroyed by lysosomes/ hydrolyctic enzymes.
3. Peptides/ antigen from virus are displayed on the cell membrane.