Equal masses of fat are mixed with equal lipase concentrations at 37 °C. A has large droplets at pH 3; B has large droplets at pH 8; C has small droplets at pH 8. This lipase works best near pH 8.
.1
Explain why B should digest fat faster than A.
[2 marks]
.2
Explain why C should be faster than B and relate this to bile.
[2 marks]
6 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A class plans to investigate how light intensity affects photosynthesis using pondweed, a lamp, a ruler, a water bath and a gas-collection syringe.
Plan an investigation that produces valid, repeatable rate comparisons.
[6 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A virus damages immune cells. Patients later get frequent infections from other pathogens. Long illness prevents some patients from working or meeting friends.
.1
Explain why other infections become more frequent.
[2 marks]
.2
Suggest two links between long illness and poorer mental health.
[2 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Plant tissue gains 4% mass at 0.20 mol/dm³ sugar and loses 4% at 0.40 mol/dm³. Assume a linear relationship between these points.
.1
Estimate the concentration giving zero net mass change.
[2 marks]
.2
Explain what zero net change means and how to improve the estimate.
[2 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
The diagram shows a student's drawing of a plant cell.
.1
The student has not drawn a cell membrane. Explain why a plant cell needs both a cell wall and a cell membrane.
[2 marks]
.2
The label 'aerobic respiration' points to the wrong structure. Name the structure it should point to, and explain why the cell needs to respire.
