Biology · Oct / Nov 2024 · Paper 41 · Question 3

prokaryote ;

letter from name

function or use

Fig. 3.1 flagellum

movement / AW

B controls what goes in and out (of

cell membrane

G the cell)

ribosome

protein synthesis

D prevents (cell) bursting

cell wall

A / provides support

plasmid

used in genetic modification

C ;;;;;

drinking contaminated water / AW ;

any four from:

1

cholera / bacterium / pathogen, produces a toxin ;

2

(toxin) causes secretion of chloride ions ;

3

into lumen / small intestine ;

4

(loss of ions) increases / AW, water potential within cell ; ora

5

water moves out of cells / blood ;

6

down water potential gradient / from high to low water potential ; 7

(out) by osmosis / through the partially permeable membranes ; 8

(causing) diarrhoea / watery faeces / AW ;

9

resulting in loss of water (from the body) ;

any six from

1

ref. to active / long-term, immunity ;

2

vaccine contains weakened / dead / AW, bacteria / pathogen ;

3

ref. to antigens of pathogen ;

4

(antigen) stimulates an immune response ;

5

lymphocytes make antibodies ;

6

antibodies bind to, antigen ;

7

ref. to, specificity / complementary (shape to antigen / pathogen) ; 8

ref. to forming memory cells ;

9

ref. to mass vaccination (programmes) ;

10 person to person transmission interrupted / AW ;

11 AVP ;