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
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]
5 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
Four plants all have genotype RR at one tested gene, but their final heights are 14, 19, 24 and 27 cm. The plants grew with different supplies of water. A student claims that these results show height cannot be inherited.
.1
Explain why the student’s conclusion is not justified.
[3 marks]
.2
Suggest how to test the effect of water while reducing genetic differences between plants.
[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]
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.
