The table shows the osmotic potential of a range of sucrose solutions.

Concentration of sucrose/mol dm3
0.30
0.35
0.40
0.45
0.50
0.60

Osmotic potential/kPa
-860
-970
-1120
-1280
-1450
-1800

(a) Analyse the data in the graph and in the table to explain how the osmotic potential of tgese onion cells could be determined.

(b) Explain why the plant tissue was left in sucrose solution for 10 minutes before the cells were observed.