A student estimated the number of daisies in a field 50 m long and 40 m wide. She placed a 0.25 m² quadrat at five random positions and counted the daisies in each.
Daisies in five quadrats: 4, 7, 0, 5, 9.
Quadrat
1
2
3
4
5
Number of daisies
4
7
0
5
9
.1
Calculate the mean number of daisies per quadrat.
[2 marks]
.2
Estimate the number of daisies in the whole field.
[3 marks]
8 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A student models a small organism as a cube with sides 3 cm long.
.1
Calculate the total surface area of the cube.
[2 marks]
.2
Calculate the volume of the cube.
[1 mark]
.3
Calculate the surface area to volume ratio of the cube.
[1 mark]
.4
A larger organism has a smaller surface area to volume ratio.
Explain why a large multicellular organism needs exchange surfaces and a transport system.
[2 marks]
.5
Explain why root hair cells need energy to take in mineral ions from the soil.
[2 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
After a meal containing carbohydrates, the concentration of glucose in the blood rises.
.1
Explain how the body returns the blood glucose concentration to normal after the meal.
[3 marks]
.2
What is the cause of type 1 diabetes?
[1 mark]
5 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Heart muscle contracts all the time, throughout life.
.1
Explain why heart muscle cells contain many mitochondria.
[2 marks]
.2
Compare aerobic respiration with anaerobic respiration in muscle cells.
[3 marks]
5 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A student investigated the effect of pH on the time taken for amylase to break down starch.
She mixed amylase, starch and a buffer solution in a water bath at 35 °C. Every 30 seconds she put a drop of the mixture onto iodine solution on a spotting tile. She recorded the time when the iodine no longer turned blue-black.
Time for starch to be broken down: pH 5, 150 s; pH 6, 90 s; pH 7, 60 s; pH 8, 120 s; pH 9, 240 s.
pH
Time for starch to be broken down (s)
5
150
6
90
7
60
8
120
9
240
.1
The rate of reaction can be found with:
rate =time1000
Calculate the rate of reaction at pH 7.
[1 mark]
.2
Explain why the starch took much longer to break down at pH 9.
[2 marks]
.3
Suggest how the student could find the optimum pH of amylase more precisely.
[1 mark]
.4
Sampling every 30 seconds limits the accuracy of the times.
Explain why.
