Bundle of content questions

Question 1

What do antigens allow the immune system to identify? (4)

Answer 1

• Pathogens
• Cells from other organisms of the same species
• Abnormal body cells
• Toxins

Question 2

Describe the mechanism of phagocytosis (6)

Answer 2

• Phagocyte has several receptors on its cell-surface membrane
• Which attach to the surface of the pathogen and ingest the pathogen
• Forming a phagosome
• Lysosomes release their hydrolytic lysozymes into the phagosome
• And these enzymes hydrolyse the pathogen
• The soluble products from the breakdown of the pathogen are absorbed into the cytoplasm of the phagocyte

Question 3

The response of T lymphocytes to a foreign antigen (3)

Answer 3

• After phagocytosis, the phagocyte places antigens from the pathogen on its cell-surface membrane
• T helper cells fit onto these antigens and this attachment activates the T cells to divide rapidly via mitosis
• The cloned cells then develop into memory cells, stimulate phagocytes to engulf pathogens by phagocytosis, stimulate B cells and activate cytotoxic T cells

Question 4

Role of helper T cells

Answer 4

• Become memory cells
• Stimulate B cells to divide
• Stimulate phagocytosis
• Activate cytotoxic T cells

Question 5

The response of B lymphocytes to a foreign antigen (4)

Answer 5

• Antigens on the surface of invading pathogens are taken up by a B cell which presents it on its surface
• Helper T cells activate B cells to divide via mitosis and produce a clone of plasma cells
• Specific antibodies which destroy the pathogen are made
• Some B cells develop into memory cells

Question 6

Structure of antibodies (3)

Answer 6

• Four polypeptide chains: two heavy and two light
• Variable region which is the binding site
• Constant region which binds to receptors on cells

Question 7

Structure of HIV (2)

Answer 7

• Lipid envelope with embedded attachment proteins

- Protein capsid where RNA and reverse transcriptase enzymes are present

Question 8

Uses of monoclonal antibodies (2)

Answer 8

• Targeting medication to specific cell types by attaching a therapeutic drug to an antibody
• Medical diagnosis.

Question 9

Ethical considerations of vaccinations & monoclonal antibodies (4)

Answer 9

• Production and testing may be done on animals
• The risks need to be balanced with the benefits
• Must be tested on humans first to determine toxicity
• Expensive to manufacture