A student investigated the uptake of two different substances in cultured cells.
The rate of uptake was measured at different concentrations of each substance in the medium surrounding the cells.
The results are shown in Fig. 16.2.
Fig. 16.2
(i) The student concluded that one substance entered the cells by simple diffusion and the other by active transport. Evaluate the student’s conclusion.
[4]
(ii) The student then added 2,4-dinitrophenol (DNP) to the cells. DNP inhibits respiration. Predict the effect of DNP on the uptake of each substance and explain your prediction.
Substance A
effect .................................................................................... explanation ........................................................................ Substance B
effect ..................................................................................... explanation .........................................................................
[4]