A scientist investigated the uptake of two dissolved substances, R and S, by cells grown in a nutrient solution.

Substance	Concentration outside the cells in mmol per dm³	Concentration inside the cells in mmol per dm³	Rate of uptake at 1% oxygen in μmol per gram of cells per hour	Rate of uptake at 20% oxygen in μmol per gram of cells per hour
R	0.5	4.0	0.6	5.4
S	6.0	1.5	3.8	4.0

Explain which transport process is mainly responsible for the uptake of substance R and substance S. Use all the data in the table.

The cells are moved to a solution containing 1.5 mmol per dm³ of substance S. The concentration of S inside the cells remains 1.5 mmol per dm³.

Predict the net movement of S across the cell membrane. Explain your answer.

A scientist investigated the uptake of two dissolved substances, R and S, by cells grown in a nutrient solution.

Substance	Concentration outside the cells in mmol per dm³	Concentration inside the cells in mmol per dm³	Rate of uptake at 1% oxygen in μmol per gram of cells per hour	Rate of uptake at 20% oxygen in μmol per gram of cells per hour
R	0.5	4.0	0.6	5.4
S	6.0	1.5	3.8	4.0

Explain which transport process is mainly responsible for the uptake of substance R and substance S. Use all the data in the table.

The cells are moved to a solution containing 1.5 mmol per dm³ of substance S. The concentration of S inside the cells remains 1.5 mmol per dm³.

Predict the net movement of S across the cell membrane. Explain your answer.

1.3 Transport in cells

1.3 Transport in cells Questions