paper 1

Question 1

give two ways in which the structure of starch is similar to cellulose

Answer 1

both are polysaccharides of glucose, both contain glycosidic bonds between glucose molecules

Question 2

how is the structure of starch different to cellulose

Answer 2

starch can be branched, cellulose is unbranched, starch contains alpha glucose cellulose contains beta glucose, starch has no microfibrils cellulose forms microfibrils

Question 3

how does a vaccine lead to the production of antibodies against a disease causing organism (5 marks)

Answer 3

vaccines contain antigens which are engulfed by phagocytes and displayed on the surface of marker cells, T cells with complementary receptor proteins bind to the antigen and stimulates B cells which divide to form clones including plasma cells which secrete a large amount of antibodies which are specific to the antigens on the disease causing organism

Question 4

describe the difference between active and passive immunity (5 marks)

Answer 4

in active immunity memory cells are produced as T