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]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
The body keeps its temperature close to 37 °C.
.1
Explain why it is important to keep body temperature close to 37 °C.
[2 marks]
.2
Which of these is an effector?
[1 mark]
.3
Name the coordination centre that receives information from temperature receptors.
[1 mark]
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.
[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]
6 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A student used a potometer to measure the rate of water uptake by a leafy shoot. An air bubble moved along a scale as the shoot took up water.
In still air the bubble moved 45 mm in 5 minutes. With a fan blowing on the shoot, the bubble moved 72 mm in 5 minutes.
.1
Calculate the rate of water uptake in still air, in mm per minute.
[1 mark]
.2
Calculate the percentage increase in the rate when the fan was on.
[2 marks]
.3
Explain why the rate of water uptake increased when the fan was on.
[2 marks]
.4
Give one variable the student should keep the same when comparing still air with moving air.
