Practical Skill AS Level

An investigation is carried out into the effect of substrate concentration on the activity of catalase enzyme. What could be the dependent variable?

• the concentration of catalase

• the pH of the enzyme solution

• the rate of production of oxygen

• the temperature of the substrate

An investigation is carried out into the effect of temperature on the activity of lipase. Separate tubes of substrate solution and enzyme solution are left in temperature-controlled water baths for ten minutes before mixing. Why is this done?

• to activate the enzyme

• to allow time for the enzyme and substrate to react

• to control the independent variable

• to keep a standardised variable constant

Which of the following is the independent variable for the investigation of the effect of sucrose concentration on plasmolysis of onion cells?

• sucrose concentration

• % plasmolysis of onion cells

• source of onion cells

• length of time of immersion

Which of the following is the control variable for the investigation of the effect of pH on the rate of activity of amylase?

• pH

• rate of activity of amylase

• temperature

• the rate of disappearance of starch

Which of the following is the dependent variable for the investigation of the effect of temperature on the percentage of open stomata in a leaf?

• wind movement

• percentage of open stomata in leaf

• humidity

• temperature

Which of the following is NOT the control variable for the investigation of the effect of temperature on the percentage of open stomata in a leaf?

• light

• humidity

• source of leaf

• temperature

A student is investigating the effect of temperature on the activity of amylase on starch. Which of the following a ways in which you could measure the dependent variable.

• By measuring the rate of disappearance of starch

• By measuring the rate of appearance of reducing sugar (maltose)

______ is the factor that changes in an investigation.

• Dependent variables

• Independent variables

• Control variables

______ is the factor that changes as a result in investigation.

• Dependent variables

• Independent variables

• Control variables

______ may affect the other variables so its must kept constant or being standardized.

• Dependent variables

• Independent variables

• Control variables