Animal cells, plant cells and bacterial cells contain different structures.
.1
What is the function of mitochondria?
[1 mark]
.2
Name the structure in a plant cell that absorbs light for photosynthesis.
[1 mark]
.3
Which two structures are found in a bacterial cell? Tick two boxes.
[2 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.
[1 mark]
6 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Tobacco mosaic virus (TMV) infects tomato and tobacco plants. HIV infects humans.
.1
TMV causes a mosaic pattern of discoloured patches on the leaves.
Explain why an infected plant grows more slowly.
[3 marks]
.2
Explain how viruses make people ill.
[2 marks]
.3
How is HIV controlled in a person who is infected?
[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]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Scientists studied the risk of lung cancer in adults who smoked different numbers of cigarettes each day. The graph shows how many times greater the risk was than for non-smokers.
051015202530510152025Cigarettes smoked per dayRisk compared with non-smokers1481522
.1
Describe the pattern shown in the graph.
[1 mark]
.2
Calculate how many times as great the risk is for a person smoking 20 cigarettes a day as for a person smoking 5 a day.
[1 mark]
.3
A correlation does not always mean that one factor causes another.
Explain what other evidence scientists needed before concluding that smoking causes lung cancer.
