OCR
GCE
Biology A
H020/02: Depth in biology
*1442429839*
AS Level
INSTRUCTIONS
• Use black ink. You can use an HB pencil, but only for graphs and diagrams.
• Write your answer to each question in the space provided. If you need extra space use
the lined pages at the end of this booklet. The question numbers must be clearly shown.
• Answer all the questions.
• Where appropriate, your answer should be supported with working. Marks might be
given for using a correct method, even if your answer is wrong.
INFORMATION
• The total mark for this paper is 70.
• The marks for each question are shown in brackets [ ].
• Quality of extended response will be assessed in questions marked with an asterisk (*).
• This document has 24 pages.
ADVICE
• Read each question carefully before you start your answer.
© OCR 2025 [601/4261/3] DC (PQ/SW) 350639/7
OCR is an exempt Charity
Turn over
1
(a) The table describes features of molecules.
Complete the table. Use ticks (3) to identify if the feature describes starch or cellulose.
Description Starch Cellulose
Is made of amylose and amylopectin
Is a long unbranched chain
, 2
Is made from β glucose molecules
(b) Students complete paper chromatography on carbohydrates.
The table shows the Rf values for known carbohydrates.
© researchgate.net, ResearchGate. Item removed due to third party copyright restrictions. Link to material - www.researchgate.net/publication/261143652_Extraction
The measurements recorded for an unknown carbohydrate were:
Distance travelled by solvent = 8.50 cm
Distance travelled by carbohydrate = 4.34 cm
Calculate the Rf value of the unknown carbohydrate and use the table to identify it.
Give your answer to 2 decimal places.
Rf value = ...............................................................
Name of carbohydrate = ...............................................................
[2] (c) Outline the role of the solvent in paper chromatography.
........................................................................................................................................
..................
........................................................................................................................................
..................
........................................................................................................................................
..................
........................................................................................................................................
..................
........................................................................................................................................
............. [2]
© OCR 2025
, 3
2
(a) Students use a model cell to investigate the effect of the thickness of the exchange
surface membrane on the rate of diffusion across the membrane.
The students are provided with dialysis tubing of different thicknesses, grade 1, grade
3 and grade 5, where grade 5 is the thickest.
They set up the apparatus as shown.
The students remove a sample of the external solution at 30 second intervals and
determine the concentration of glucose (mmol dm–3) in the sample.
Glass rod
String
Dialysis tubing
Glucose solution
External solution
Beaker
The table shows their results.
Concentration of glucose found in the samples of external
Grade of solution taken at 30 s intervals (mmol dm–3)
dialysis tubing
0s 30 s 60 s 90 s 120 s
1 0.00 1.31 2.52 3.59 4.80
3 0.00 0.82 2.24 2.39 3.31
5 0.00 0.31 0.64 0.96 1.22
(i) Identify the independent variable and the dependent variable in this experiment.
Independent variable
...............................................................................................................................................
........... ...................................................................................................................................
.......................
Dependent variable
........................................................................................................................................
..................
........................................................................................................................................
..................
(ii) Suggest two improvements to this experiment to increase the accuracy of the results.
© OCR 2025 Turn over
, 4
Improvement
1 .................................................................................................................................
........................................................................................................................................
..................
Improvement
2 .................................................................................................................................
........................................................................................................................................
..................
(iii) Suggest a conclusion that can be drawn from the data in the table.
You should give evidence to support your conclusion.
........................................................................................................................................
..................
........................................................................................................................................
..................
........................................................................................................................................
..................
........................................................................................................................................
..................
........................................................................................................................................
............. [2]
(b) State one similarity and one difference between simple diffusion and facilitated
diffusion.
Similarity .........................................................................................................................
..................
........................................................................................................................................
..................
Difference ......................................................................................................................
...................
........................................................................................................................................
..................
[2] (c) Using your knowledge of the phospholipid bilayer in plasma membranes,
explain how an increase in temperature affects the permeability of the membrane.
........................................................................................................................................
..................
........................................................................................................................................
..................
© OCR 2025
GCE
Biology A
H020/02: Depth in biology
*1442429839*
AS Level
INSTRUCTIONS
• Use black ink. You can use an HB pencil, but only for graphs and diagrams.
• Write your answer to each question in the space provided. If you need extra space use
the lined pages at the end of this booklet. The question numbers must be clearly shown.
• Answer all the questions.
• Where appropriate, your answer should be supported with working. Marks might be
given for using a correct method, even if your answer is wrong.
INFORMATION
• The total mark for this paper is 70.
• The marks for each question are shown in brackets [ ].
• Quality of extended response will be assessed in questions marked with an asterisk (*).
• This document has 24 pages.
ADVICE
• Read each question carefully before you start your answer.
© OCR 2025 [601/4261/3] DC (PQ/SW) 350639/7
OCR is an exempt Charity
Turn over
1
(a) The table describes features of molecules.
Complete the table. Use ticks (3) to identify if the feature describes starch or cellulose.
Description Starch Cellulose
Is made of amylose and amylopectin
Is a long unbranched chain
, 2
Is made from β glucose molecules
(b) Students complete paper chromatography on carbohydrates.
The table shows the Rf values for known carbohydrates.
© researchgate.net, ResearchGate. Item removed due to third party copyright restrictions. Link to material - www.researchgate.net/publication/261143652_Extraction
The measurements recorded for an unknown carbohydrate were:
Distance travelled by solvent = 8.50 cm
Distance travelled by carbohydrate = 4.34 cm
Calculate the Rf value of the unknown carbohydrate and use the table to identify it.
Give your answer to 2 decimal places.
Rf value = ...............................................................
Name of carbohydrate = ...............................................................
[2] (c) Outline the role of the solvent in paper chromatography.
........................................................................................................................................
..................
........................................................................................................................................
..................
........................................................................................................................................
..................
........................................................................................................................................
..................
........................................................................................................................................
............. [2]
© OCR 2025
, 3
2
(a) Students use a model cell to investigate the effect of the thickness of the exchange
surface membrane on the rate of diffusion across the membrane.
The students are provided with dialysis tubing of different thicknesses, grade 1, grade
3 and grade 5, where grade 5 is the thickest.
They set up the apparatus as shown.
The students remove a sample of the external solution at 30 second intervals and
determine the concentration of glucose (mmol dm–3) in the sample.
Glass rod
String
Dialysis tubing
Glucose solution
External solution
Beaker
The table shows their results.
Concentration of glucose found in the samples of external
Grade of solution taken at 30 s intervals (mmol dm–3)
dialysis tubing
0s 30 s 60 s 90 s 120 s
1 0.00 1.31 2.52 3.59 4.80
3 0.00 0.82 2.24 2.39 3.31
5 0.00 0.31 0.64 0.96 1.22
(i) Identify the independent variable and the dependent variable in this experiment.
Independent variable
...............................................................................................................................................
........... ...................................................................................................................................
.......................
Dependent variable
........................................................................................................................................
..................
........................................................................................................................................
..................
(ii) Suggest two improvements to this experiment to increase the accuracy of the results.
© OCR 2025 Turn over
, 4
Improvement
1 .................................................................................................................................
........................................................................................................................................
..................
Improvement
2 .................................................................................................................................
........................................................................................................................................
..................
(iii) Suggest a conclusion that can be drawn from the data in the table.
You should give evidence to support your conclusion.
........................................................................................................................................
..................
........................................................................................................................................
..................
........................................................................................................................................
..................
........................................................................................................................................
..................
........................................................................................................................................
............. [2]
(b) State one similarity and one difference between simple diffusion and facilitated
diffusion.
Similarity .........................................................................................................................
..................
........................................................................................................................................
..................
Difference ......................................................................................................................
...................
........................................................................................................................................
..................
[2] (c) Using your knowledge of the phospholipid bilayer in plasma membranes,
explain how an increase in temperature affects the permeability of the membrane.
........................................................................................................................................
..................
........................................................................................................................................
..................
© OCR 2025
