2025 OCR A-LEVEL BIOLOGY A H420/02 Biological Diversity Question Paper & Mark Scheme (Merged)
June 2025 [VERIFIED]
, 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
© OCR 2025 Turn over
, 4
D Only 1
Your answer [1]
© OCR 2025
June 2025 [VERIFIED]
, 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
© OCR 2025 Turn over
, 4
D Only 1
Your answer [1]
© OCR 2025
