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]
4 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A model of hormonal contraception keeps oestrogen and progesterone at concentrations that inhibit FSH and LH.
.1
Explain how this model reduces the chance of pregnancy.
[3 marks]
.2
Explain why this hormone model does not predict protection from sexually transmitted pathogens.
[1 mark]
6 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Two plants grow under the same bright, warm conditions. One has plentiful water; the other has dry soil and closes many stomata.
Explain how closing stomata helps the dry-soil plant but can limit its growth.
[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]
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.
