AS & A Level Biology - 9700 Paper 3 2016 Winter Zone 1

You are required to make a serial dilution of the 1% reducing sugar solution, R, which reduces the concentration by half between each successive dilution.
Decide how many different concentrations you will prepare for your serial dilution.
You will need to prepare 10 cm³ 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 as many extra beakers as you need for your serial dilution.
For each beaker:
• state, under the beaker, the volume and concentration of the reducing sugar solution available for use in the investigation
• use one arrow, with a label above the beaker, to show the volume and concentration of reducing sugar 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) You will be required to carry out the Benedict’s test on each of the reducing sugar solutions you have prepared. You will use 2 cm³ of reducing sugar solution for each test.
State the volume of Benedict’s solution you will use for each reducing sugar test.
Explain why you have selected this volume.
volume of Benedict’s solution ................................. cm³
explanation ......................................................................................................................................

(iii) Prepare the space below and record your results.
..............................................................................................................................

(iv) A student carried out step 1 to step 7 and recorded the result for one of the concentrations as 42 s. Calculate the rate of this reaction.
You may lose marks if you do not show your working.
.................................................. s^-1

(v) State the variables that you will need to standardise so that you can compare the results of the Benedict’s test on M1 and M2 with those recorded in (a)(iii).
.............................................................................................................................................................

(vi) Record your results for M1 and M2.
M1 .....................................................................
M2 .....................................................................

(vii) Use your results in (a)(iii) to estimate the percentage concentration of reducing sugar in each of M1 and M2.
M1 ..................................................................................................................
M2 ..................................................................................................................

(viii) State which sample, M1 or M2, would be most suitable for a person who is unable to digest lactose. Give a reason for your answer.
sample ..............................................................................................................
reason ..............................................................................................................

In most people the reducing sugar lactose is hydrolysed by an enzyme during digestion to produce monosaccharides which are absorbed into the blood.
Some people do not produce this enzyme. When they drink animal milk, the lactose is undigested.
Certain bacteria use the undigested lactose for respiration and produce hydrogen gas. This enters the bloodstream, and is transported to the lungs where it is breathed out (exhaled).
Scientists can measure the concentration of hydrogen in exhaled air.
A scientist gave a person who does not produce this enzyme a drink of animal milk. The effect of drinking milk containing lactose was investigated by measuring the concentration of hydrogen in exhaled air every 20 minutes for 80 minutes.
The results are shown in Table 1.1.
[Table_1]
(i) Plot a graph of the data shown in Table 1.1.


(b) Draw a large plan diagram of the half of the organ shown by the shaded area in Fig 1.3.

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

You are required to make a serial dilution of the 1% reducing sugar solution, R, which reduces the concentration by half between each successive dilution.
Decide how many different concentrations you will prepare for your serial dilution.
You will need to prepare 10 cm³ 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 as many extra beakers as you need for your serial dilution.
For each beaker:
• state, under the beaker, the volume and concentration of the reducing sugar solution available for use in the investigation
• use one arrow, with a label above the beaker, to show the volume and concentration of reducing sugar 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) You will be required to carry out the Benedict’s test on each of the reducing sugar solutions you have prepared. You will use 2 cm³ of reducing sugar solution for each test.
State the volume of Benedict’s solution you will use for each reducing sugar test.
Explain why you have selected this volume.
volume of Benedict’s solution ................................. cm³
explanation ......................................................................................................................................

(iii) Prepare the space below and record your results.
..............................................................................................................................

(iv) A student carried out step 1 to step 7 and recorded the result for one of the concentrations as 42 s. Calculate the rate of this reaction.
You may lose marks if you do not show your working.
.................................................. s^-1

(v) State the variables that you will need to standardise so that you can compare the results of the Benedict’s test on M1 and M2 with those recorded in (a)(iii).
.............................................................................................................................................................

(vi) Record your results for M1 and M2.
M1 .....................................................................
M2 .....................................................................

(vii) Use your results in (a)(iii) to estimate the percentage concentration of reducing sugar in each of M1 and M2.
M1 ..................................................................................................................
M2 ..................................................................................................................

(viii) State which sample, M1 or M2, would be most suitable for a person who is unable to digest lactose. Give a reason for your answer.
sample ..............................................................................................................
reason ..............................................................................................................

In most people the reducing sugar lactose is hydrolysed by an enzyme during digestion to produce monosaccharides which are absorbed into the blood.
Some people do not produce this enzyme. When they drink animal milk, the lactose is undigested.
Certain bacteria use the undigested lactose for respiration and produce hydrogen gas. This enters the bloodstream, and is transported to the lungs where it is breathed out (exhaled).
Scientists can measure the concentration of hydrogen in exhaled air.
A scientist gave a person who does not produce this enzyme a drink of animal milk. The effect of drinking milk containing lactose was investigated by measuring the concentration of hydrogen in exhaled air every 20 minutes for 80 minutes.
The results are shown in Table 1.1.
[Table_1]
(i) Plot a graph of the data shown in Table 1.1.


(b) Draw a large plan diagram of the half of the organ shown by the shaded area in Fig 1.3.

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

(a) (i) Observe the upper epidermis at the top of the leaf on J1. Select one group of three cells with:
• two cells from the upper epidermis
• one adjacent (touching) cell from the tissue below.
Each cell of the group must touch at least one of the other cells.
Make a large drawing of this group of three cells.
Use one ruled label line and label to identify the cell wall of one cell.

(ii) State the function of the cell you have drawn from the tissue below the epidermis. Identify one observable feature of this cell that supports your answer.

function of cell .................................................................................................................
observable feature ...........................................................................................................[2]

(iv) A student used a clear plastic ruler to measure the field of view of a microscope. The student replaced the ruler with a slide of a leaf and estimated the diameter of the midrib. Using these results the student calculated the actual diameter of the midrib.
State how this student could have modified their method to obtain a more accurate result. State the apparatus the student would use and describe the method.

apparatus .................................................................................................................
..............................................................................................................................

method ..................................................................................................................
..............................................................................................................................
..............................................................................................................................
..............................................................................................................................
.............................................................................................................................. [3]

(a) (i) Observe the upper epidermis at the top of the leaf on J1. Select one group of three cells with:
• two cells from the upper epidermis
• one adjacent (touching) cell from the tissue below.
Each cell of the group must touch at least one of the other cells.
Make a large drawing of this group of three cells.
Use one ruled label line and label to identify the cell wall of one cell.

(ii) State the function of the cell you have drawn from the tissue below the epidermis. Identify one observable feature of this cell that supports your answer.

function of cell .................................................................................................................
observable feature ...........................................................................................................[2]

(iv) A student used a clear plastic ruler to measure the field of view of a microscope. The student replaced the ruler with a slide of a leaf and estimated the diameter of the midrib. Using these results the student calculated the actual diameter of the midrib.
State how this student could have modified their method to obtain a more accurate result. State the apparatus the student would use and describe the method.

apparatus .................................................................................................................
..............................................................................................................................

method ..................................................................................................................
..............................................................................................................................
..............................................................................................................................
..............................................................................................................................
.............................................................................................................................. [3]