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 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A clinic considers transferring two embryos instead of one. Two-embryo transfer may increase pregnancy probability per transfer, but also increases the chance of multiple pregnancy.
Evaluate the use of two-embryo transfer. Include scientific, practical and ethical considerations.
[6 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A shrub produces flowers visited by bees. The bees obtain nectar, and pollen is transferred between flowers. A long drought reduces the shrub population.
.1
Explain why the relationship is an example of interdependence.
[2 marks]
.2
Explain how the drought could affect the bees even if they are not directly harmed by dry air.
[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]
5 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A flask of yeast and glucose releases 18 cm³ carbon dioxide in 6 minutes at 30 °C and 3 cm³ in 6 minutes at 60 °C. A student says yeast respires fastest at any higher temperature.
.1
Calculate the ratio of the rate at 30 °C to the rate at 60 °C, expressed as a number of times.
