Practice questions

Multiple-choice and free-response questions with worked answers.

1.Multiple choiceUnit 1
Which property of water is most directly responsible for the movement of water up the xylem of a tall tree?

Multiple choice
AWater has a high specific heat.BHydrogen bonds make water molecules cohesive and adhesive.CIce is less dense than liquid water.DWater is a good solvent for ions.
2.Free responseUnit 2
Potato cores are placed in sucrose solutions of different concentrations for 24 hours. Cores in 0.0 M sucrose gain mass; cores in 0.6 M sucrose lose mass.

(a) Identify the dependent variable.

(b) Explain why the cores in 0.6 M sucrose lose mass.
3.Multiple choiceUnit 3
The rate of an enzyme-catalysed reaction falls sharply when the temperature is raised from 40 °C to 60 °C. Which explanation is best supported?

Multiple choice
AThe substrate is used up faster at higher temperatures.BMolecules collide less often at higher temperatures.CBonds that maintain the enzyme's shape break, so the active site changes shape.DThe enzyme is converted into the product.