AS & A Level Biology - 9700 Paper 3 2016 Summer Zone 5

(a) You are required to make a serial dilution of the 1% glucose solution, G, which reduces the concentration by half between each successive dilution.

You will need to prepare 10cm³ of each concentration.

Fig. 1.1 shows the first two beakers you will use to make your serial dilution.

(i) Complete Fig. 1.1 by drawing the extra beakers you need for your serial dilution.

For each beaker:
• state, under the beaker, the concentration and volume of the glucose solution available for use in the investigation
• use one arrow, with a label above the beaker, to show the concentration and volume of glucose 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.

[Image_1: Fig. 1.1]

Proceed as follows:
1. Set up a water-bath and heat to boiling ready for step 6.
2. Prepare the concentrations of glucose solution as shown in Fig. 1.1.
3. Put 2cm³ of 1% glucose solution into a test-tube.

(ii) State the smallest division on the syringe you used in step 3.

.......................................................................................................

State the actual error when using this syringe.

.......................................................................................................[1]

Calculate the percentage error when using this syringe.
You may lose marks if you do not show your working.

percentage error .................................................[1]

4. Put 2cm³ of Benedict’s solution into the same test-tube as step 3.
5. Shake the test-tube gently to mix the contents.

Read step 6 to step 9 before proceeding.

You are required to:
• observe the contents of the test-tube continuously while the test-tube is heated
for 60 seconds
• record the time taken for the first appearance of a colour change, if a colour change
occurs during this 60 seconds
• record the colour after heating for 60 seconds.

6. Put this test-tube into the water-bath you prepared in step 1 and start timing.
7. Record the time taken for the first appearance of a colour change in Table 1.1. Do not stop the clock and continue heating until 60 seconds.

If there is no colour change after 60 seconds record the time as ‘more than 60’.
8. At 60 seconds remove the test-tube from the water-bath, gently shake, and record the colour of the Benedict’s solution in Table 1.1.
9. Repeat step 3 to step 8 for each of the glucose solutions you prepared in step 2.

You are not required to repeat this experiment.

(iii) Complete the column headings and record your results in Table 1.1.

[Table_1]

(iv) Describe how you will standardise the Benedict’s test in order to enable you to estimate the concentration of glucose in P.

.......................................................................................................

.......................................................................................................

.......................................................................................................

.......................................................................................................[2]

10. Repeat step 3 to step 8 using solution P.

(v) Record your results for solution P.

time taken for the first appearance of a colour change .......................................................
colour of Benedict’s at 60 seconds ...............................................[1]

(vi) Estimate the concentration of glucose in P, using the colour of Benedict’s at 60 seconds recorded in Table 1.1 and (a)(v).

.......................................................................................................[1]

(vii) Describe one improvement to allow a more accurate estimate of the concentration of glucose in P to be obtained using the colour of Benedict’s at 60 seconds.

.......................................................................................................

.......................................................................................................

.......................................................................................................[1]

(viii) Describe how your results for the time taken for the first appearance of a colour change can be used to produce a more accurate estimate of the concentration of glucose in P than the one given in (a)(vi).

.......................................................................................................

.......................................................................................................

.......................................................................................................

.......................................................................................................

.......................................................................................................[2]

(b) A scientist studied the change in the concentration of glucose in blood plasma after eating a meal containing carbohydrate. Samples of blood plasma were taken at regular intervals after eating the meal and the concentration of glucose in each sample was measured.

The results are shown in Table 1.2.

[Table_2]

(i) Plot a graph of the data shown in Table 1.2.

[Graph Grid]
[4]

(ii) Calculate the percentage increase in concentration of glucose in the blood plasma between 0 minutes and 20 minutes after eating the meal. You may lose marks if you do not show all your working.

percentage increase .................................................[1]

(iii) Use one label line and the label X to show on the graph where the rate of diffusion of glucose into the blood is most rapid. [1]

(iv) Suggest one reason for the concentration of glucose in blood plasma decreasing between 60 minutes and 80 minutes after eating the meal.

.......................................................................................................

.......................................................................................................

.......................................................................................................[1]

(a) You are required to make a serial dilution of the 1% glucose solution, G, which reduces the concentration by half between each successive dilution.

You will need to prepare 10cm³ of each concentration.

Fig. 1.1 shows the first two beakers you will use to make your serial dilution.

(i) Complete Fig. 1.1 by drawing the extra beakers you need for your serial dilution.

For each beaker:
• state, under the beaker, the concentration and volume of the glucose solution available for use in the investigation
• use one arrow, with a label above the beaker, to show the concentration and volume of glucose 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.

[Image_1: Fig. 1.1]

Proceed as follows:
1. Set up a water-bath and heat to boiling ready for step 6.
2. Prepare the concentrations of glucose solution as shown in Fig. 1.1.
3. Put 2cm³ of 1% glucose solution into a test-tube.

(ii) State the smallest division on the syringe you used in step 3.

.......................................................................................................

State the actual error when using this syringe.

.......................................................................................................[1]

Calculate the percentage error when using this syringe.
You may lose marks if you do not show your working.

percentage error .................................................[1]

4. Put 2cm³ of Benedict’s solution into the same test-tube as step 3.
5. Shake the test-tube gently to mix the contents.

Read step 6 to step 9 before proceeding.

You are required to:
• observe the contents of the test-tube continuously while the test-tube is heated
for 60 seconds
• record the time taken for the first appearance of a colour change, if a colour change
occurs during this 60 seconds
• record the colour after heating for 60 seconds.

6. Put this test-tube into the water-bath you prepared in step 1 and start timing.
7. Record the time taken for the first appearance of a colour change in Table 1.1. Do not stop the clock and continue heating until 60 seconds.

If there is no colour change after 60 seconds record the time as ‘more than 60’.
8. At 60 seconds remove the test-tube from the water-bath, gently shake, and record the colour of the Benedict’s solution in Table 1.1.
9. Repeat step 3 to step 8 for each of the glucose solutions you prepared in step 2.

You are not required to repeat this experiment.

(iii) Complete the column headings and record your results in Table 1.1.

[Table_1]

(iv) Describe how you will standardise the Benedict’s test in order to enable you to estimate the concentration of glucose in P.

.......................................................................................................

.......................................................................................................

.......................................................................................................

.......................................................................................................[2]

10. Repeat step 3 to step 8 using solution P.

(v) Record your results for solution P.

time taken for the first appearance of a colour change .......................................................
colour of Benedict’s at 60 seconds ...............................................[1]

(vi) Estimate the concentration of glucose in P, using the colour of Benedict’s at 60 seconds recorded in Table 1.1 and (a)(v).

.......................................................................................................[1]

(vii) Describe one improvement to allow a more accurate estimate of the concentration of glucose in P to be obtained using the colour of Benedict’s at 60 seconds.

.......................................................................................................

.......................................................................................................

.......................................................................................................[1]

(viii) Describe how your results for the time taken for the first appearance of a colour change can be used to produce a more accurate estimate of the concentration of glucose in P than the one given in (a)(vi).

.......................................................................................................

.......................................................................................................

.......................................................................................................

.......................................................................................................

.......................................................................................................[2]

(b) A scientist studied the change in the concentration of glucose in blood plasma after eating a meal containing carbohydrate. Samples of blood plasma were taken at regular intervals after eating the meal and the concentration of glucose in each sample was measured.

The results are shown in Table 1.2.

[Table_2]

(i) Plot a graph of the data shown in Table 1.2.

[Graph Grid]
[4]

(ii) Calculate the percentage increase in concentration of glucose in the blood plasma between 0 minutes and 20 minutes after eating the meal. You may lose marks if you do not show all your working.

percentage increase .................................................[1]

(iii) Use one label line and the label X to show on the graph where the rate of diffusion of glucose into the blood is most rapid. [1]

(iv) Suggest one reason for the concentration of glucose in blood plasma decreasing between 60 minutes and 80 minutes after eating the meal.

.......................................................................................................

.......................................................................................................

.......................................................................................................[1]

(a) An eyepiece graticule scale can be used to measure the layers of tissues and to help draw a plan diagram with the correct shape and proportions of the tissues, without needing to calibrate the eyepiece graticule scale.

You are required to use a sharp pencil for drawings.

(i) Draw a large plan diagram of part of the organ as shown by the shaded area in Fig. 2.1. Use one ruled label line and the letter Z to identify the position of the tissue which prevents the flow of water through the apoplast pathway.
[Image_1: Fig. 2.1]

(ii) Identify the organ on L1. Describe one observable feature that supports your identification.

name of organ ..........................................................

feature ................................................................. [1]

(iii) Observe the organ on L1 in the region between the epidermis and the vascular tissue (the cortex).
Select one group of four adjacent (touching) cells from the cortex. Each cell of this group 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 cytoplasm in one of the cells. [5]
(c) Prepare the space below so that it is suitable for you to record the observable similarities between the plant organ on L1 and that shown in Fig. 2.2.
Record your observations in the space you have prepared. [3]

(a) An eyepiece graticule scale can be used to measure the layers of tissues and to help draw a plan diagram with the correct shape and proportions of the tissues, without needing to calibrate the eyepiece graticule scale.

You are required to use a sharp pencil for drawings.

(i) Draw a large plan diagram of part of the organ as shown by the shaded area in Fig. 2.1. Use one ruled label line and the letter Z to identify the position of the tissue which prevents the flow of water through the apoplast pathway.
[Image_1: Fig. 2.1]

(ii) Identify the organ on L1. Describe one observable feature that supports your identification.

name of organ ..........................................................

feature ................................................................. [1]

(iii) Observe the organ on L1 in the region between the epidermis and the vascular tissue (the cortex).
Select one group of four adjacent (touching) cells from the cortex. Each cell of this group 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 cytoplasm in one of the cells. [5]
(c) Prepare the space below so that it is suitable for you to record the observable similarities between the plant organ on L1 and that shown in Fig. 2.2.
Record your observations in the space you have prepared. [3]