AS & A Level Biology - 9700 Paper 3 2018 Winter Zone 4

(a) (i) Record the volume of iodine solution added to sample A and sample W.
volume added to A .................. cm^3
volume added to W .................. cm^3 [1]

(a) (ii) Table 1.2 shows how to make up two of the concentrations you will use, 0.10% and 0.00%.
Decide which other concentrations of ascorbic acid to prepare using simple (proportional) dilutions of A.
Complete Table 1.2 to show how you will prepare the other concentrations.
$$\begin{array}{|c|c|c|} \hline \text{percentage concentration of} & \text{volume of A} & \text{volume of W} \\ \text{ascorbic acid} & /\text{cm}^3 & /\text{cm}^3 \\ \hline 0.10 & 20.00 & 0.00 \\ \hline 0.00 & 0.00 & 20.00 \\ \hline \end{array}$$ [2]

(a) (iii) Record your results in an appropriate table for the known concentrations of ascorbic acid. [4]

(a) (iv) Record the volume of iodine solution added to X and Y.
volume added to X .................................
volume added to Y ................................. [1]

(a) (v) Complete Fig. 1.2 to show the position on the line of each of the percentage concentrations of ascorbic acid shown in Table 1.2.
Using your results in (a)(iv), put the labels X and Y on Fig. 1.2 to show an estimate of the concentrations of ascorbic acid in X and Y. [1]

(a) (vi) Identify one significant source of error in this investigation.
..............................................................................................................................................
..............................................................................................................................................
[1]

(a) (vii) Suggest how you would make three improvements to this investigation in order to obtain a more accurate estimate of the concentration of ascorbic acid in X and Y.
..............................................................................................................................................
..............................................................................................................................................
.............................................................................................................................................. [3]

(b) A student carried out further investigations on ascorbic acid to test its effect on the reaction of amylase on starch. Maltose is a product of the hydrolysis of starch.
Different concentrations of ascorbic acid were added to standard mixtures of amylase and starch. The student measured the mass of maltose produced.
The results are shown in Table 1.4.
$$\begin{array}{|c|c|} \hline \text{percentage concentration of} & \text{mass of maltose} \\ \text{ascorbic acid} & \text{produced/mg} \\ \hline 0.000 & 97 \\ \hline 0.002 & 52 \\ \hline 0.004 & 42 \\ \hline 0.006 & 33 \\ \hline 0.008 & 25 \\ \hline 0.010 & 19 \\ \hline \end{array}$$
(i) Plot a graph of the data in Table 1.4 on the grid in Fig. 1.3.
Use a sharp pencil for drawing graphs. [4]

(b) (ii) Use your graph to find the mass of maltose produced when 0.005% of ascorbic acid was used.
Show on the graph how you determined your answer.
mass of maltose = ..................................... [2]

(b) (iii) Suggest one explanation for the results between 0.000% and 0.010%.
..............................................................................................................................................
..............................................................................................................................................
.............................................................................................................................................. [3]

(a) (i) Record the volume of iodine solution added to sample A and sample W.
volume added to A .................. cm^3
volume added to W .................. cm^3 [1]

(a) (ii) Table 1.2 shows how to make up two of the concentrations you will use, 0.10% and 0.00%.
Decide which other concentrations of ascorbic acid to prepare using simple (proportional) dilutions of A.
Complete Table 1.2 to show how you will prepare the other concentrations.
$$\begin{array}{|c|c|c|} \hline \text{percentage concentration of} & \text{volume of A} & \text{volume of W} \\ \text{ascorbic acid} & /\text{cm}^3 & /\text{cm}^3 \\ \hline 0.10 & 20.00 & 0.00 \\ \hline 0.00 & 0.00 & 20.00 \\ \hline \end{array}$$ [2]

(a) (iii) Record your results in an appropriate table for the known concentrations of ascorbic acid. [4]

(a) (iv) Record the volume of iodine solution added to X and Y.
volume added to X .................................
volume added to Y ................................. [1]

(a) (v) Complete Fig. 1.2 to show the position on the line of each of the percentage concentrations of ascorbic acid shown in Table 1.2.
Using your results in (a)(iv), put the labels X and Y on Fig. 1.2 to show an estimate of the concentrations of ascorbic acid in X and Y. [1]

(a) (vi) Identify one significant source of error in this investigation.
..............................................................................................................................................
..............................................................................................................................................
[1]

(a) (vii) Suggest how you would make three improvements to this investigation in order to obtain a more accurate estimate of the concentration of ascorbic acid in X and Y.
..............................................................................................................................................
..............................................................................................................................................
.............................................................................................................................................. [3]

(b) A student carried out further investigations on ascorbic acid to test its effect on the reaction of amylase on starch. Maltose is a product of the hydrolysis of starch.
Different concentrations of ascorbic acid were added to standard mixtures of amylase and starch. The student measured the mass of maltose produced.
The results are shown in Table 1.4.
$$\begin{array}{|c|c|} \hline \text{percentage concentration of} & \text{mass of maltose} \\ \text{ascorbic acid} & \text{produced/mg} \\ \hline 0.000 & 97 \\ \hline 0.002 & 52 \\ \hline 0.004 & 42 \\ \hline 0.006 & 33 \\ \hline 0.008 & 25 \\ \hline 0.010 & 19 \\ \hline \end{array}$$
(i) Plot a graph of the data in Table 1.4 on the grid in Fig. 1.3.
Use a sharp pencil for drawing graphs. [4]

(b) (ii) Use your graph to find the mass of maltose produced when 0.005% of ascorbic acid was used.
Show on the graph how you determined your answer.
mass of maltose = ..................................... [2]

(b) (iii) Suggest one explanation for the results between 0.000% and 0.010%.
..............................................................................................................................................
..............................................................................................................................................
.............................................................................................................................................. [3]

M1 is a slide of a stained transverse section through a plant root.
You are not expected to be familiar with this specimen.

Use a sharp pencil for drawing.

(a) (i) Draw a large plan diagram of the transverse section through the root.
Use one ruled label line and label to identify the cortex.

You are expected to draw the correct shape and proportions of the different tissues.

(a) (ii) Observe the cells in the epidermis and the cells directly beneath the epidermis.
Select a group of four touching cells. These four cells must include:
• two epidermal cells that are touching each other
• two cells directly beneath the epidermis that are touching each other and are also touching at least one of the epidermal cells.

Make a large drawing of this group of four touching cells.
Use one ruled label line and label to identify the cell wall of one cell.

You are expected to draw the correct shape and proportions of the different cells.

(b) Fig. 2.1 is a photomicrograph of a stained transverse section through a root of a different type of plant.
You are not expected to be familiar with this specimen.

[Image_1: Fig. 2.1]
Use the line E–F to determine the simplest whole number ratio of the total diameter of the root to the diameter of the central vascular tissue.

Show your working.

ratio ..........................................

(c) Prepare an appropriate table so that it is suitable for you to record observable differences between the root on M1 and the root in Fig. 2.1.
Record your observations in the table you have prepared.

M1 is a slide of a stained transverse section through a plant root.
You are not expected to be familiar with this specimen.

Use a sharp pencil for drawing.

(a) (i) Draw a large plan diagram of the transverse section through the root.
Use one ruled label line and label to identify the cortex.

You are expected to draw the correct shape and proportions of the different tissues.

(a) (ii) Observe the cells in the epidermis and the cells directly beneath the epidermis.
Select a group of four touching cells. These four cells must include:
• two epidermal cells that are touching each other
• two cells directly beneath the epidermis that are touching each other and are also touching at least one of the epidermal cells.

Make a large drawing of this group of four touching cells.
Use one ruled label line and label to identify the cell wall of one cell.

You are expected to draw the correct shape and proportions of the different cells.

(b) Fig. 2.1 is a photomicrograph of a stained transverse section through a root of a different type of plant.
You are not expected to be familiar with this specimen.

[Image_1: Fig. 2.1]
Use the line E–F to determine the simplest whole number ratio of the total diameter of the root to the diameter of the central vascular tissue.

Show your working.

ratio ..........................................

(c) Prepare an appropriate table so that it is suitable for you to record observable differences between the root on M1 and the root in Fig. 2.1.
Record your observations in the table you have prepared.