Respiration (Cambridge (CIE) IGCSE Biology)

Exam Questions

3 hours32 questions

4 marks

A woodlouse is a small animal.

The rate of respiration of a woodlouse can be measured using a simple respirometer as shown in Fig. 1.

As the woodlouse respires the drop of coloured liquid moves along the capillary tube.

Fig. 1

(i)

Record the position of the drop of coloured liquid in the capillary tube shown in Fig. 1 at the start and after 30 minutes.

Give your answer in mm.

[1]

(ii)

Calculate the distance moved by the drop of coloured liquid in 30 minutes.

Give your answer in mm.

[1]

(iii)

Calculate the rate of movement of the drop of coloured liquid in mm per minute.

Give your answer in mm per minute and to one decimal place.

[2]

How did you do?

8 marks

The rate of movement of the drop of coloured liquid along the respirometer can be used to estimate the rate of respiration.

A student used a respirometer to investigate the rate of respiration in four animal species.

The results are shown in Table 1.

Table 1

Animal species	Rate of movement of the drop of coloured liquid / mm per minute
Animal species	Trial 1	Trial 2	Trial 3	Mean
A	1.5	1.7	1.3
B	0.9	1.0	0.7	0.9
C	2.4	2.6	2.5	2.5
D	1.9	2.0	1.9	1.9

(i)

Calculate the missing mean for animal species A.

[1]

(ii)

Plot a bar chart on the grid to show the mean rate of movement of the drop of coloured liquid in the capillary tube for the four animal species.

[3]

(iii)

State the letter of the animal species which has the highest rate of respiration.

[1]

(iv)

Suggest a suitable control for the investigation described in 1b).

[1]

(v)

The student decided it would be better to calculate the rate of respiration per gram of animal so that the values could be compared.

Describe how the student could find out the rate of respiration per gram of animal.

[2]

How did you do?

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4 marks

A student investigated the rate of respiration of yeast at two different temperatures.

Step 1

The student was provided with a yeast suspension which also contained glucose. Two identical sets of equipment were set up as shown in Fig. 1

061062-may-2018-paper-6-q1-respiration---atp-sq

Fig. 1

Step 2	One set of the equipment shown in Fig. 1 was placed into a warm water-bath and the starting temperature of the water-bath was recorded as 50°C. The other set was placed into a cool water-bath which had a starting temperature of 25°C. The volume of water in each water bath was the same.

Step 3	The student counted the number of gas bubbles produced by the yeast suspension in five minutes and recorded the results in a tally chart. This is shown in Fig. 2.

061062-may-2018-paper-6-q1-respiration-tally---atp-sq

Fig. 2

(i)

Prepare a table and record the student’s results shown in Fig. 2.

[3]

Step 4

At the end of the investigation the final temperature of the water in both water baths was measured. The results are shown in Fig. 3

061062-may-2018-paper-6-q1-thermometeres---atp-sq

Fig. 3

(ii)

Use the information in step 2 and Fig. 3 to complete Table 1.

Table 1

Water bath	Starting temperature / °C	Final temperature / °C
Warm
Cool

[1]

How did you do?

7 marks

(i)

State a conclusion for the results.

[1]

(ii)

Counting the number of gas bubbles produced may not be an accurate method of measurement.

Explain why and suggest an improvement.

[2]

(iii)

Identify a variable that should have been kept constant during this investigation but was not. Suggest how this variable could have been kept constant.

[2]

(iv)

Identify the variable that was changed (independent variable) and the variable that was measured (dependent variable) in this investigation.

[2]

How did you do?

10 marks

A group of scientists investigated the effect of different concentrations of glucose on the rate of carbon dioxide production in yeast cells. They measured the volume of carbon dioxide produced by the yeast cells in five minutes.

The scientists decided to test their method before beginning the investigation.

They performed three trials using one concentration of glucose.

The results are given in Table 2.

Table 2

Trial	Volume of carbon dioxide produced in 5 minutes / cm³
1	13.6
2	14.3
3	12.9

(i)

Calculate the average volume of carbon dioxide produced in 5 minutes.

Give your answer in cm³

Calculate the average rate of carbon dioxide production per minute.

Give your answer in cm³ per minute

[2]

(ii)

The scientists performed the investigation. Their results are shown in Table 3.

Table 3

Percentage concentration of glucose	Average rate of carbon dioxide production / cm³ per minute
0.5	1.3
1.0	2.6
1.5	3.8
2.0	4.3
2.5	4.4
3.0	4.4

Plot a graph on the grid, using the data in Table 3, to show the effect of glucose concentration on the rate of carbon dioxide production. Include a line of best fit.

061062-may-2018-paper-6-q1-graph-paper---atp-sq

[4]

(iii)

Describe the effect of glucose concentration on the rate of carbon dioxide production by respiring yeast cells, shown in your graph.

[3]

(iv)

Estimate the concentration of glucose the scientists used to test their method. Use your answer for c)i) and your graph to find this value.

Give your answer using the unit %.

[1]

How did you do?

5 marks

(i)

Describe how the student could show that the glucose used in the investigation is a simple (reducing) sugar.

[3]

(ii)

Identify one hazard when testing for simple (reducing) sugars.

Describe one precaution that could be taken to reduce the risk.

[2]

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3 marks

An investigation was conducted to determine the effect of temperature on the rate of respiration in yeast.

The experimental procedure was conducted as follows:

A thermostatically controlled water bath was set up at 20°C
The investigators added 10 cm³ of a yeast suspension and 20 cm³ of a 10% glucose solution to each of three test-tubes
The test-tubes were placed in the water bath and left for 10 minutes
After 10 minutes, five drops of methylene blue were added to each test-tube using a dropper pipette and the test-tubes were then shaken for 10 seconds to mix
The test-tubes were returned to the water bath
A stop watch was started when the drops were added
The time taken for the methylene blue to turn colourless in each test tube was recorded
Steps 1 to 7 were repeated at temperatures of 30°C, 40°C, 50°C and 60°C

Fig. 1 shows the experimental set up of one test tube.

Fig. 1

The mean time taken for a colour change to occur was calculated at each temperature and this was used to calculate the rate of respiration.

Table 1 shows the results of the investigation.

Table 1

temperature / °C	time taken to turn colourless / s	rate of respiration / s^-1
20	604	0.0017
30	345	0.0029
40	105	0.0095
50	274	0.0036
60	583

(i)

Calculate the rate of respiration at 60°C.

[1]

(ii)

Identify a potential source of error in step 7 and suggest a possible improvement.

[2]

How did you do?

9 marks

(i)

State a conclusion for the results.

[2]

(ii)

Identify two variables that should be kept constant and describe how this would be achieved for each.

[4]

(iii)

Using a dropper pipette to add the methylene blue may not be the most accurate method.

Explain why and suggest an improvement.

[2]

(iv)

Identify the dependent variable in this investigation.

[1]

How did you do?

5 marks

(i)

Use the data in Table 1 to plot a line graph on the grid to show the effect of temperature on the rate of respiration.

[4]

(ii)

Estimate the rate of respiration at 36°C.

Indicate on your graph to show how the answer was obtained.

[1]

How did you do?

2 marks

Explain the importance of repeating this experiment at least three times.

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