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
After rainfall, water enters soil and is taken up by trees. On a sunny day the air above the woodland contains more water vapour.
.1
Explain how water moves from the soil to the atmosphere through the trees.
[2 marks]
.2
Describe two later processes that return this water to land as part of the cycle.
[2 marks]
6 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A student writes: “Homeostasis stops all changes. Only the brain controls it. Muscles and glands detect every stimulus.”
Evaluate this description of homeostasis. Explain how automatic control systems actually work.
[6 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A contraceptive comparison gives typical-use pregnancies per 100 users in one year: method A, a daily hormonal pill, 8; method B, an implant, 1. Neither method protects against sexually transmitted infections.
.1
Calculate the difference in expected pregnancies between 500 users of A and 500 users of B for one year.
[2 marks]
.2
A person often forgets daily medication and also wants infection protection. Evaluate these methods for that person.
