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(a) You are required to make concentrations of ethanol using simple dilution of the 1.0% ethanol, E, which reduces the concentration by 0.25% between each successive dilution.
You will need to prepare 10 cm3 of each concentration.
Table 1.1 shows how to make up two of the concentrations of ethanol you will use.
(i) Complete Table 1.1 by showing as many extra concentrations as you need.
For each concentration state:
• the volume of 1.0% ethanol, E, you will use
• the volume of distilled water, W, you will use
• the resulting percentage concentration of ethanol.
[Table_1.1]
Proceed as follows:
1. Prepare the concentrations of ethanol as shown in Table 1.1 in the beakers provided.
2. Label the test-tubes with the concentrations of ethanol.
3. Put 5 cm3 of each dilution of ethanol into the labelled test-tubes.
4. Label one test-tube U and put 5 cm3 of U into this test-tube.
5. Remove the pieces of plant tissue from the container labelled P and put them on the white tile. Cut the ends off each piece of plant tissue.
6. Cut the plant tissue into equal lengths of approximately 2 cm.
7. Empty the coloured water from P into the container labelled For Waste.
8. Put the pieces of plant tissue back into P and cover the pieces with tap water from the container labelled T.
9. Change the tap water five times to remove excess methylene blue solution, either using a syringe or by pouring off the water into the container labelled For Waste.
Fig. 1.1 shows how you will set up the apparatus for each concentration of ethanol.
10. Remove the pieces of plant tissue from P and put them on a paper towel.
11. Put one piece of plant tissue into each test-tube, including U and start timing. Leave for 10 minutes.
While you are waiting continue with Question 1.
After 10 minutes you will need to remove the plant tissue from each test-tube so that the colour of each solution can be recorded.
12. After 10 minutes pour the solution and the piece of plant tissue from one of the test-tubes into the beaker labelled R.
13. Put the piece of plant tissue into the container labelled For waste. Pour the solution back into the test-tube.
14. Rinse beaker R with water from the container labelled For washing.
15. Repeat step 12 to step 14 with each of the remaining test-tubes, including U.
16. Arrange the test-tubes in the order of intensity of blue colour from lowest intensity to highest intensity.
17. Observe the colour in the test-tubes and match the intensity of colour in each test-tube to the key shown in Fig. 1.2.
You may observe the same intensity of colour for more than one test-tube.
18. Record your results for the known concentrations of ethanol in (a)(ii) and record the result for U in (a)(iii).
(ii) Prepare the space below and record your results for the known concentrations of ethanol.
(iii) Record your result for U and use this and your results in (a)(ii) to estimate the concentration of ethanol in U.
result for U ...............................................................
estimated concentration of ethanol in U ............................................................... [2]
(iv) Explain how the ethanol affected the release of methylene blue from the plant cells...............................................................
...............................................................[3]
(v) This procedure investigated the effect of the concentration of ethanol on the release of methylene blue solution from pieces of stained plant tissue.
To modify this procedure for investigating another variable, the independent variable (concentration of ethanol) would need to be standardised. Describe how the concentration of ethanol could be standardised.
...............................................................
Consider how you would modify this procedure to investigate the effect of temperature on the release of methylene blue solution from pieces of stained plant tissue. Describe how this independent variable, temperature, could be investigated.
...............................................................[3]
(b) A student investigated the effect of placing pieces of tissue from a potato in sucrose solutions of different concentrations. At the start, each sample of potato tissue was weighed and the initial mass was recorded. Then each sample of potato tissue was placed into a different concentration of sucrose solution. After a set time the potato tissue was removed and the final mass of the potato tissue was recorded. The percentage change in mass for each sample of potato tissue was calculated.
The results of the student's investigation are shown in Table 1.2. Note: the percentage change in mass is shown to the nearest 0.5%.
[Table_1.2]
(i) Complete Table 1.2 by calculating the percentage change in mass for the 0.2 mol dm-3 sucrose solution. [1]
(ii) Plot a graph of the data shown in Table 1.2.
[Graph]
(iii) Use your graph to estimate the percentage change in mass of the potato tissue for a sucrose concentration of 0.7 mol dm-3.
Show on your graph how you estimated the percentage change in mass.
percentage change in mass ............................................................... [2]
542
562
571
(a) You are required to make concentrations of ethanol using simple dilution of the 1.0% ethanol, E, which reduces the concentration by 0.25% between each successive dilution.
You will need to prepare 10 cm3 of each concentration.
Table 1.1 shows how to make up two of the concentrations of ethanol you will use.
(i) Complete Table 1.1 by showing as many extra concentrations as you need.
For each concentration state:
• the volume of 1.0% ethanol, E, you will use
• the volume of distilled water, W, you will use
• the resulting percentage concentration of ethanol.
[Table_1.1]
Proceed as follows:
1. Prepare the concentrations of ethanol as shown in Table 1.1 in the beakers provided.
2. Label the test-tubes with the concentrations of ethanol.
3. Put 5 cm3 of each dilution of ethanol into the labelled test-tubes.
4. Label one test-tube U and put 5 cm3 of U into this test-tube.
5. Remove the pieces of plant tissue from the container labelled P and put them on the white tile. Cut the ends off each piece of plant tissue.
6. Cut the plant tissue into equal lengths of approximately 2 cm.
7. Empty the coloured water from P into the container labelled For Waste.
8. Put the pieces of plant tissue back into P and cover the pieces with tap water from the container labelled T.
9. Change the tap water five times to remove excess methylene blue solution, either using a syringe or by pouring off the water into the container labelled For Waste.
Fig. 1.1 shows how you will set up the apparatus for each concentration of ethanol.
10. Remove the pieces of plant tissue from P and put them on a paper towel.
11. Put one piece of plant tissue into each test-tube, including U and start timing. Leave for 10 minutes.
While you are waiting continue with Question 1.
After 10 minutes you will need to remove the plant tissue from each test-tube so that the colour of each solution can be recorded.
12. After 10 minutes pour the solution and the piece of plant tissue from one of the test-tubes into the beaker labelled R.
13. Put the piece of plant tissue into the container labelled For waste. Pour the solution back into the test-tube.
14. Rinse beaker R with water from the container labelled For washing.
15. Repeat step 12 to step 14 with each of the remaining test-tubes, including U.
16. Arrange the test-tubes in the order of intensity of blue colour from lowest intensity to highest intensity.
17. Observe the colour in the test-tubes and match the intensity of colour in each test-tube to the key shown in Fig. 1.2.
You may observe the same intensity of colour for more than one test-tube.
18. Record your results for the known concentrations of ethanol in (a)(ii) and record the result for U in (a)(iii).
(ii) Prepare the space below and record your results for the known concentrations of ethanol.
(iii) Record your result for U and use this and your results in (a)(ii) to estimate the concentration of ethanol in U.
result for U ...............................................................
estimated concentration of ethanol in U ............................................................... [2]
(iv) Explain how the ethanol affected the release of methylene blue from the plant cells...............................................................
...............................................................[3]
(v) This procedure investigated the effect of the concentration of ethanol on the release of methylene blue solution from pieces of stained plant tissue.
To modify this procedure for investigating another variable, the independent variable (concentration of ethanol) would need to be standardised. Describe how the concentration of ethanol could be standardised.
...............................................................
Consider how you would modify this procedure to investigate the effect of temperature on the release of methylene blue solution from pieces of stained plant tissue. Describe how this independent variable, temperature, could be investigated.
...............................................................[3]
(b) A student investigated the effect of placing pieces of tissue from a potato in sucrose solutions of different concentrations. At the start, each sample of potato tissue was weighed and the initial mass was recorded. Then each sample of potato tissue was placed into a different concentration of sucrose solution. After a set time the potato tissue was removed and the final mass of the potato tissue was recorded. The percentage change in mass for each sample of potato tissue was calculated.
The results of the student's investigation are shown in Table 1.2. Note: the percentage change in mass is shown to the nearest 0.5%.
[Table_1.2]
(i) Complete Table 1.2 by calculating the percentage change in mass for the 0.2 mol dm-3 sucrose solution. [1]
(ii) Plot a graph of the data shown in Table 1.2.
[Graph]
(iii) Use your graph to estimate the percentage change in mass of the potato tissue for a sucrose concentration of 0.7 mol dm-3.
Show on your graph how you estimated the percentage change in mass.
percentage change in mass ............................................................... [2]
549
580
589
K1 is a slide of a stained transverse section through a plant root.
You are not expected to be familiar with this specimen.
You are required to use a sharp pencil for drawings.
(a) (i) Draw a large plan diagram of the quarter of the root shown by the shaded area in Fig. 2.1.
Use one ruled label line and label to identify the xylem.
[Image_1: Fig. 2.1]
You are expected to draw the correct shape and proportions of the different tissues.
(ii) Observe the central tissue in the root on K1. These cells are not identical.
Select one group of four adjacent (touching) cells which show some of the differences between these cells. Each cell must touch at least two of the other cells.
Make a large drawing of this group of four cells.
Use one ruled label line and label to identify the cell wall of one cell.
(b) Prepare the space below so that it is suitable for you to record the observable differences between the root on K1 and the stem in Fig. 2.2.
Record your observations in the space you have prepared. [4]
593
595
565
K1 is a slide of a stained transverse section through a plant root.
You are not expected to be familiar with this specimen.
You are required to use a sharp pencil for drawings.
(a) (i) Draw a large plan diagram of the quarter of the root shown by the shaded area in Fig. 2.1.
Use one ruled label line and label to identify the xylem.
[Image_1: Fig. 2.1]
You are expected to draw the correct shape and proportions of the different tissues.
(ii) Observe the central tissue in the root on K1. These cells are not identical.
Select one group of four adjacent (touching) cells which show some of the differences between these cells. Each cell must touch at least two of the other cells.
Make a large drawing of this group of four cells.
Use one ruled label line and label to identify the cell wall of one cell.
(b) Prepare the space below so that it is suitable for you to record the observable differences between the root on K1 and the stem in Fig. 2.2.
Record your observations in the space you have prepared. [4]
568
529
596
