exam questions
Cards (11)
- Explain why the destruction of T helper cells causes the symptoms of aids (4)- Lack of T helper cells reduces cytokine production- Thus, less activation of B cells and less production of B effector cells thus plasma cells- Reducing anti body productions- There is an increased risk of opportunistic infections
- Explain the role of T cells in the body of person infected with HPV virus (3)- A vaccinated person will have memory T cells- These recognise antigens specific to HPV- T helper cells that activate B cells- Formation of T killer cells destroys cells infected with virus
- Explain the role of T cells in the immunity to Ebola virus that develops following the use of this vaccine (3)- T helper cells can bind to antigen on the APC- Thus, leading to the production of active t helper cells/ t memory cells- The T helper cells activate the B cells to develop into B effector cells which differentiate into plasma cells- capable of producing antibodies- The memory cells remain in the body so antibodies can be produced quickly on reinfection.
- Describe how macrophages injest the bacteria (2)- Engulfing (via phagocytosis) extending out cell membrane surrounding pathogen- As a result, bacterium inside vacuole of WBC.
- Explain why the activity of these bacteria and the inhibition of T cells means that a person may quickly develop severe symptoms leading to death (4)(tb)- Reduced and weakened immune response due to loss of T cells- Talk about role of T helper cells, no T killer cells and effect of no B cells- Causing opportunistic infections.
- Which type of cell in the human immune system is infected by HIV (1)- T helper cell
- Explain how both T cells and B cells work together to effectively combat infectious disease (4)- T cells bind to the antigen on the APC- T killer cells combat the infection that has entered host cells- T helper cells signal to help activate b cells- T killer cells kill infected cells- B cells combat infection in blood plasma- B plasma cells secrete antibodies that lead to phagocytosis- Both form memory cells to remain in the blood and protect against future infection by that antigen.
- Explain how antibody causes pathogens to agglutinate and explain the consequences of this (4)- One antibody can bind to antigens on 2 separate pathogen cells- Holding the pathogens together- Can be clumped together by multiple antigen- antibody complexes between cells- Allows phagocytosis to act on multiple pathogens at once- Stops them spreading- So tightly clumped to cannot exchange oxygen or food with surroundings- So metabolic processes stop and the cells die
- Describe the stages involved in the activation of T-helper cells (5)- Macrophage engulfs bacterium with its antigens- Macrophage then presents bacterium’s antigens on major histone complexes, becomes an antigen presenting cell- T helper cell binds to this APC via complementary receptors, causing T cell to become activated- Activated T helper cell, divides and differentiates by mitosis to form active T helper cells and T memory cells
- Describe the stages involved in the effector stage (5)- B cells (via complementary receptors) bind to antigens on a bacterium, engulf and become an antigen presenting cell.- Activated T helper cells bind to the antigen presenting cell via its complementary receptors- This causes cytokines to be released. Cytokines stimulate B cells to differentiate into B effector cells and B memory cells- B effector cells differentiate into plasma cells which secrete antibodies
- Describe the role of opsonisation by antibodies (4)- Antibodies bind to antigens on the bacterium- Macrophages bind to these antibodies via their complementary receptors and engulf bacterium antibodies- Vacuole of macrophage binds with lysosomes and digestive enzymes including lysozyme are released into vacuole, digesting, and killing the bacterium.