Oxford Cambridge and RSA
Thursday 22 May 2025 – Morning
AS Level Biology A
H020/02 Depth in biology
Time allowed: 1 hour 30 minutes
You can use:
* 1 4 4 2 4 2 9 8 3 9 *
• a scientific or graphical calculator
• a ruler (cm/mm)
* H 0 2 0 0 2 *
Please write clearly in black ink. Do not write in the barcodes.
Centre number Candidate number
First name(s)
Last name
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] OCR is an exempt Charity
DC (PQ/SW) 350639/7 Turn over
for more: tyrionpapers.com
, 2
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
Is made from β glucose molecules
[3]
(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_of_Sugars_from_Black_Gram_Peels_by_Reversed-Phase_Liquid_Chromatography_Systems_and_Identification_by_TLC_and_Mass_Analy
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]
© OCR 2025
for more: tyrionpapers.com
, 3
(c) Outline the role of the solvent in paper chromatography.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..................................................................................................................................................... [2]
© OCR 2025 Turn over
for more: tyrionpapers.com
, 4
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
© OCR 2025
for more: tyrionpapers.com
Thursday 22 May 2025 – Morning
AS Level Biology A
H020/02 Depth in biology
Time allowed: 1 hour 30 minutes
You can use:
* 1 4 4 2 4 2 9 8 3 9 *
• a scientific or graphical calculator
• a ruler (cm/mm)
* H 0 2 0 0 2 *
Please write clearly in black ink. Do not write in the barcodes.
Centre number Candidate number
First name(s)
Last name
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] OCR is an exempt Charity
DC (PQ/SW) 350639/7 Turn over
for more: tyrionpapers.com
, 2
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
Is made from β glucose molecules
[3]
(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_of_Sugars_from_Black_Gram_Peels_by_Reversed-Phase_Liquid_Chromatography_Systems_and_Identification_by_TLC_and_Mass_Analy
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]
© OCR 2025
for more: tyrionpapers.com
, 3
(c) Outline the role of the solvent in paper chromatography.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..................................................................................................................................................... [2]
© OCR 2025 Turn over
for more: tyrionpapers.com
, 4
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
© OCR 2025
for more: tyrionpapers.com
