5/6 markers

Question 1

describe and explain how the lungs are adapted to allow rapid exchange of oxygen between air in the alveoli & blood in the capillaries around them (5)

Answer 1

-many alveoli provide a large surface area
-many capillaries provide a large surface area so fast diffusion
-alveoli/capillary walls/epithelium are thin so short diffusion distance/pathway

Question 2

scientists believe that it may be possible to develop vaccines that make use of miccrofold cells. explain how this sort of vaccine would lead to a person developing immunity to the pathogen (5)

Answer 2

-vaccine contains antigen
-microfold cells bind and transport antigen
-T-cells activate B-cells
-B cells divide
-B cells produce antibodies
-memory cells produced
-more antibodies produced faster in secondary response

Question 3

explain the role of B-lymphocytes and T-lymphocytes in the defence of the body against a virus infection (6)

Answer 3

-B-lymphocytes produced antibodies/involved in humorous response
-T-lymphocytes involved in cell mediated immunity
-macrophages present antigens
-specific B-lymphocytes recognise/bind to antigen
-increase in numbers by mitosis
-antibodies bind to virus
-memory cells produced by first exposure /cloned on second exposure
-T-lymphocytes produce chemicals which aid B-lymphocyte cloning