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rtrtrtFriday 13 June 2025 – Morningyyyyyyyy
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A-Level OCR 2025 Biology A
hththtA Level Biology Ahhjjjjjjjjj Paper 2
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H420/02 Biological diversityrrrrrrrrrrrr 4444444 44444444444
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rtrtrTime allowed: 2 hours 15 minutessssssssssss
, 2
Section A
You should spend a maximum of 20 minutes on this section.
Write your answer to each question in the box provided.
1 Hydrogen bonds are important for the physical and chemical properties of water.
How do hydrogen bonds form in water?
A Electronegative (δ–) oxygen atoms are attracted to the electropositive (δ+) hydrogen atoms
of adjacent water molecules.
B Electronegative (δ–) oxygen atoms are attracted to the electropositive (δ+) hydrogen atoms
within the same water molecule.
C Electropositive (δ+) oxygen atoms are attracted to the electronegative (δ–) hydrogen atoms
of adjacent water molecules.
D Electropositive (δ+) oxygen atoms are attracted to the electronegative (δ–) hydrogen atoms
within the same water molecule.
Your answer [1]
2 Water has many properties that are important for living organisms.
Which property of water molecules explains why small animals, such as pond skaters, are able to
move over the surface of water without sinking?
A Adhesion
B Buoyancy
C Cohesion
D Density
Your answer [1]
© OCR 2025
, 3
3 What is a disadvantage of using microorganisms to make food for human consumption?
A Competition from contaminating microorganisms can reduce yield.
B Food produced by microorganisms is low in fat.
C Microorganisms can be grown on waste materials.
D Use of microorganisms for food production raises fewer ethical concerns than use of
animals.
Your answer [1]
4 Culturing microorganisms on nutrient agar requires aseptic techniques.
What is not part of a standard aseptic procedure when culturing microorganisms?
A Disinfect the work area before starting.
B Ensure equipment does not touch any unsterilised surfaces before use.
C Pass the agar plate through a Bunsen flame before use.
D Work near a Bunsen flame.
Your answer [1]
5 Batch fermentation with microorganisms is used to produce a range of useful substances.
Which of the following are important for achieving maximum yield during a batch fermentation
process?
1. Temperature should be maintained close to the optimum.
2. Temperature should be low to reduce costs.
3. Substrate should be constantly added to maintain a high concentration.
A 1, 2 and 3
B Only 1 and 2
C Only 2 and 3
D Only 1
Your answer [1]
© OCR 2025 Turn over
, 4
6 Some students are conducting an osmosis investigation using cylinders of potato.
They cut cylinders of potato 50 mm long using the ruler shown in the diagram.
0 10 20 30 40 50 60 70 80 90 100
mm
What is the percentage uncertainty in the length of the potato cylinders?
A 0.25%
B 0.5%
C 1%
D 2%
Your answer [1]
© OCR 2025
jgjfjfgfjgfgfjgkfjkgjkfjkjkjkkkkkkkkkkkkkkkkkkkkkkkkk
rtrtrtFriday 13 June 2025 – Morningyyyyyyyy
ttttttttttttttttttttttttttttttttttttttttttttttttttttt
A-Level OCR 2025 Biology A
hththtA Level Biology Ahhjjjjjjjjj Paper 2
ttthhhhhhhhhhhtt B-Dfdfdfgg ddddddddddddd f
H420/02 Biological diversityrrrrrrrrrrrr 4444444 44444444444
yeueuueuueueueu
rtrtrTime allowed: 2 hours 15 minutessssssssssss
, 2
Section A
You should spend a maximum of 20 minutes on this section.
Write your answer to each question in the box provided.
1 Hydrogen bonds are important for the physical and chemical properties of water.
How do hydrogen bonds form in water?
A Electronegative (δ–) oxygen atoms are attracted to the electropositive (δ+) hydrogen atoms
of adjacent water molecules.
B Electronegative (δ–) oxygen atoms are attracted to the electropositive (δ+) hydrogen atoms
within the same water molecule.
C Electropositive (δ+) oxygen atoms are attracted to the electronegative (δ–) hydrogen atoms
of adjacent water molecules.
D Electropositive (δ+) oxygen atoms are attracted to the electronegative (δ–) hydrogen atoms
within the same water molecule.
Your answer [1]
2 Water has many properties that are important for living organisms.
Which property of water molecules explains why small animals, such as pond skaters, are able to
move over the surface of water without sinking?
A Adhesion
B Buoyancy
C Cohesion
D Density
Your answer [1]
© OCR 2025
, 3
3 What is a disadvantage of using microorganisms to make food for human consumption?
A Competition from contaminating microorganisms can reduce yield.
B Food produced by microorganisms is low in fat.
C Microorganisms can be grown on waste materials.
D Use of microorganisms for food production raises fewer ethical concerns than use of
animals.
Your answer [1]
4 Culturing microorganisms on nutrient agar requires aseptic techniques.
What is not part of a standard aseptic procedure when culturing microorganisms?
A Disinfect the work area before starting.
B Ensure equipment does not touch any unsterilised surfaces before use.
C Pass the agar plate through a Bunsen flame before use.
D Work near a Bunsen flame.
Your answer [1]
5 Batch fermentation with microorganisms is used to produce a range of useful substances.
Which of the following are important for achieving maximum yield during a batch fermentation
process?
1. Temperature should be maintained close to the optimum.
2. Temperature should be low to reduce costs.
3. Substrate should be constantly added to maintain a high concentration.
A 1, 2 and 3
B Only 1 and 2
C Only 2 and 3
D Only 1
Your answer [1]
© OCR 2025 Turn over
, 4
6 Some students are conducting an osmosis investigation using cylinders of potato.
They cut cylinders of potato 50 mm long using the ruler shown in the diagram.
0 10 20 30 40 50 60 70 80 90 100
mm
What is the percentage uncertainty in the length of the potato cylinders?
A 0.25%
B 0.5%
C 1%
D 2%
Your answer [1]
© OCR 2025
