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(a) (i) Complete Fig. 1.1 to show how you will make two further concentrations of C, starting with the 3% solution, C.
Proceed as follows:
1. Make the concentrations of C as stated in (a)(i).
2. Label test-tubes with W and with the concentrations of C.
3. Put 1 cm3 of W into the test-tube labelled W and put 5 cm3 of H into the same test-tube. Mix well.
4. Put a thermometer into the contents of the test-tube. Record the temperature.
5. Stir Y and put 1 cm3 of Y into the same test-tube. Mix well.
6. Start timing and record the temperature of the contents of the test-tube every 30 seconds up to 210 seconds.
7. Repeat steps 3 to 6 replacing the 1 cm3 of W with 1 cm3 of the lowest concentration of C.
8. Repeat step 7 with the other concentrations of C.
(ii) Prepare the space below to record your results.
(iii) Explain the effect of the 3% copper sulfate solution on the enzyme-catalysed reaction.
(iv) Identify two significant sources of error in this investigation.
(v) Describe three modifications to this investigation which would improve the confidence in your results.
(vi) Describe how you would set up a control for this investigation.
(vii) State the value of the smallest division on the scale of your thermometer.
smallest division ........................................................
State the actual error in measuring a temperature of 30°C using this thermometer.
30°C ± ...................................................°C
(b) (i) Plot a graph of the data shown in Table 1.1.
[Table_1]
[Graph]
(b) (ii) Explain the relationship between the concentration of catalase solution and the hydrolysis of hydrogen peroxide.
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L1 is a slide of a transverse section showing a tubular part of the digestive system of a mammal.
You are not expected to have studied this material.
(a) Draw a large plan diagram showing only the features of the wall of the tube as in the sector shaded in Fig. 2.1.
Fig. 2.1
On your diagram, use a label line and label to show the position of the lumen.
Annotate your diagram to describe one difference between the innermost layer and outermost layer.
Fig. 2.2 shows a diagram of a view of a stage micrometer scale that is being used to calibrate an eyepiece graticule.
One division, on either the stage micrometer scale or the eyepiece graticule, is the distance between two adjacent lines.
The length of one division on this stage micrometer is 0.1 mm.
Fig. 2.2
(b) (i) Using this stage micrometer, where one division is 0.1 mm, calculate the actual length of one eyepiece graticule unit using Fig. 2.2 by completing Fig. 2.3.
Step 1
1 eyepiece graticule unit = ext{.....................} divided by ext{.....................} = ext{.....................} mm
Step 2
Convert the answer to a measurement with the unit most suitable for use in light microscopy.
ext{.....................} multiplied by ext{.....................} = ext{.....................}
Fig. 2.3
(ii) Fig. 2.4 shows a photomicrograph taken using the same microscope with the same lenses as Fig. 2.2.
Use the calibration of the eyepiece graticule unit from (b)(i) and Fig. 2.4 to calculate the actual length of the fold shown by X to Z.
Fig. 2.4
You will lose marks if you do not show all the steps in your calculation and do not use the appropriate units.
Fig. 2.5 is a photomicrograph showing a transverse section through a part of the specimen on slide L1.
Fig. 2.5
(c) Make a large drawing of the four cells, labelled P, on Fig. 2.5.
On your drawing, use a label line and label to show one nucleus.
Fig. 2.6 is a photomicrograph showing a transverse section through a different organ in the same mammal.
Fig. 2.6
(d) Prepare the space below so that it is suitable for you to record two observable differences between the specimen on slide L1 and in Fig. 2.6.
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