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(a) You will need to:
• make a serial dilution of 1.0% protein solution, $P$, which reduces the concentration by half between each successive dilution
• prepare 10 cm\(^3\) of each concentration of protein solution.
Fig. 1.1 shows the first two beakers you will use to make your serial dilution.
(i) Complete Fig. 1.1 by drawing as many extra beakers as you need for your serial dilution.
For each beaker:
• state, under the beaker, the volume and concentration of protein solution available for use in the investigation
• use one arrow with a label, above the beaker, to show the volume and concentration of protein solution added to prepare the concentration
• use another arrow with a label, above the beaker, to show the volume of $W$ added to prepare the concentration.
(ii) After step 7 you will see some of the colours in Table 1.2.
Record the colours, in an appropriate table, by using the letters in Table 1.2.
You may use the same letters for more than one test-tube.
It may help to observe the colour with a piece of white card behind the test-tube.
(iii) State the colour of $U$ after step 7. ............................................................
(iv) Complete Fig. 1.2 to show the position on the line of each of the percentage concentrations of protein solution in (a)(i).
Using your results in (a)(ii) and (a)(iii), put the label $U$ on Fig. 1.2 to show an estimate of the concentration of protein in $U$.
(v) Suggest how you could change the independent variable to have more confidence in your estimate of the concentration of protein in $U$. ............................................................................................................................................
(vi) Suggest the apparatus that could be used to measure the concentration of protein in $U$ more accurately. ............................................................................................................................................
(b) The concentration of protein in blood plasma from five people with the same infection was measured for 11 days.
The results are shown in Table 1.3.
(i) Complete Table 1.3 by calculating the mean at 8 days.
Space for working.
[Table_1.3]
(ii) Plot a graph of the mean values shown in Table 1.3 on the grid in Fig. 1.3.
Use a sharp pencil for drawing graphs.
(iii) Explain, using your knowledge of the immune system, the increase in the concentration of protein in blood plasma between day 0 and day 6. ............................................................................................................................................
587
513
511
L1 is a slide of a stained transverse section through a plant leaf.
You are not expected to be familiar with this specimen.
The transverse section may contain more than one bulge, as shown in Fig. 2.1.
(a) Select a field of view so that you can observe:
* the largest bulge
* the different tissues shown by the shaded area in Fig. 2.1.
Use a sharp pencil for drawing.
You are expected to draw the correct shape and proportions of the different tissues.
(i) Draw a large plan diagram from the selected field of view which has:
* part of the epidermis
* the vascular tissue
* any other observable tissues.
Use one ruled label line and label to identify the upper epidermis. [6]
(ii) Observe the upper epidermis of the leaf on L1.
Select a line of four adjacent, touching cells that make up this tissue.
Each cell must touch at least one of the other cells.
Make a large drawing of this line of four cells.
Use one ruled label line and label to identify the cell wall of one cell. [5]
(b) Use the magnification and the line X on Fig. 2.2 to calculate the actual depth of the midrib.
Show all the steps in your working and use appropriate units.
actual depth of midrib = ................................................. [5]
(c) Identify the observable differences between the leaf on L1 and the leaf in Fig. 2.2.
Record the observable differences in Table 2.1. [3]
[Table_1]
510
578
587
