1|Page
AQA BIOLOGY QUESTIONS AND ANSWERS ALL THE
PARTS INCLUDED CURRENT TESTED IN AQA BIOLOGY
EXAM 2025-2026 TESTBANK
Table of Contents
1. Lipids .................................................................................................................................................................. 2
2. Carbohydrates ..................................................................................................................................................... 5
3.Higher - infection, diseases and response .......................................................................................................... 10
3. Antibiotics ......................................................................................................................................................... 14
4. Organisation ...................................................................................................................................................... 18
5. Cell Biology ...................................................................................................................................................... 20
GCSE AQA Biology - Infection and response ...................................................................................................... 22
6. cell structure and cell organisation ................................................................................................................... 29
7.Cells Notes ......................................................................................................................................................... 33
AQA Biology GCSE Topic 2: Organisation ......................................................................................................... 36
,2|Page
1. Lipids
How many types of lipid are there?
1) Triglycerides
2)Phospholipids
3) Steroids
What is each lipid type made of?
1) 3 fatty acid molecules + 1 glycerol molecule
2) 2 fatty acids + glycerol + phosphate
3) 4 fused rings
Describe what the solubility of lipids is in certain conditions
- Insoluble in water
- Soluble in organic solvents eg. ethanol
- Soluble in cell membrane as it controls what enters the cell
How are triglycerides formed?
3 condensation reactions
What are the products of the condensation reaction of a triglyceride?
1 triglyceride molecule and 3 water molecules
What bonds form between the H of glycerol and OH of the fatty acid?
Ester bonds
What does R on a triglyceride refer to?
Hydrocarbon chain
Describe how an ester bond is formed between a glycerol and a fatty acid tail. What is this process called?
A condensation reaction occurs between the OH of the carboxyl group (COOH) of the fatty acid and the H of
the OH of the glycerol molecule which removes one water molecule and forms an ester bond. Process is called
esterification
What are the 2 types of R group?
Saturated and unsaturated
What is a saturated R group?
Hydrocarbon chain with no double bonds between C atoms
What is an unsaturated R group?
,3|Page
Hydrocarbon chain with at least one double bonds between C atoms
What is the shape of an unsaturated R group?
Kinked due to the double bond
What state is saturated triglyceride at room temperature and why?
Solid as the straight chains lie on top of each other
What is the purpose of a triglyceride?
Storage of energy as it contains lots of chemical energy
What is a monounsaturated fatty acid and what is it's state?
One double bond between C atoms ∴ liquid at room temperature as they cannot pack closely together
What is a polyunsaturated fatty acid?
More than one double bond between C atoms
What is the structure of each type of Cis and trans unsaturated fats and explain their shape?
Cis: H atoms on same side of double bond ∴ there is a kink in the chain
Trans: H atoms on opposite sides of the double bond ∴ no kink
Describe how the structure of triglycerides relates to their function
- High ratio of energy storing C-H bonds : C atoms so store energy
- Low mass : energy ratio so can store lots of energy in small spaces
- Large and polar ∴ insoluble so storage in cells not affected by water potential or osmosis
- Release H2O when oxidised so important source of water especially for animals living in dry desert
Phospholipid
a) What is the function of a it?
b) What does it allow to diffuse?
a) It is a lipid that forms a bilayer to make up cell membranes
b) Non-polar / small molecules
What is the purpose of the arrangement of the phospholipid bilayer?
To avoid water soluble substance from entering the cell
Describe how the structure of phospholipids relates to their function
- Phosphate heads are polar/hydrophilic so are attracted to water ∴ orient to aqueous environment either side of
membrane
, 4|Page
- Fatty acid tails are nonpolar/hydrophobic so are repelled by water ∴ orient to interior of membrane
- Can combine with carbohydrates to form glycolipids which are important in cell-recognition
What bonds bond the phosphate group and fatty acids to the glycerol?
Ester bonds
What do all fatty acid molecules have?
- Carboxylic acid: COOH
- Hydrocarbon chain
- Methyl group: CH3
What are some roles of lipids?
EW PETC
- Energy: oxidation releases energy (more than carbohydrates)
- Membranes: phospholipid bilayer
- Electrical insulation (nerves): myelin sheath
- Thermal insulation: subcutaneous fat (underneath the skin) eg. blubber on seals
- Waterproofing: birds (hunting on water need to remain dry), leaves (to avoid transpiration, waxy cuticle made
of lipids), skin
- Cushioning of vital organs: surrounding organs such as liver and kidneys
Describe the mechanism of waterproofing
- Lipids are hydrophobic so repel water
- Oily secretions from sebaceous glands on skin of mammals prevent fur and hair becoming waterlogged
Describe how lipids can be used in insulation
- Lipids are poor conductors of heat and hydrophilic ions
- Triglycerides are stores in adipose tissue under skin in subcutaneous fat
- ... to insulate body
- Adipose tissue has limited blood supply to further reduce heat loss
- Myelin wrapped around axons of neurons to insulate fibres and prevent movement of K+ and Na+, gives rise
to saltatory conduction which speeds up the conduction of nerve impulses
Describe the chemical test for lipids
1) Cut up a small sample of the food you want to test
AQA BIOLOGY QUESTIONS AND ANSWERS ALL THE
PARTS INCLUDED CURRENT TESTED IN AQA BIOLOGY
EXAM 2025-2026 TESTBANK
Table of Contents
1. Lipids .................................................................................................................................................................. 2
2. Carbohydrates ..................................................................................................................................................... 5
3.Higher - infection, diseases and response .......................................................................................................... 10
3. Antibiotics ......................................................................................................................................................... 14
4. Organisation ...................................................................................................................................................... 18
5. Cell Biology ...................................................................................................................................................... 20
GCSE AQA Biology - Infection and response ...................................................................................................... 22
6. cell structure and cell organisation ................................................................................................................... 29
7.Cells Notes ......................................................................................................................................................... 33
AQA Biology GCSE Topic 2: Organisation ......................................................................................................... 36
,2|Page
1. Lipids
How many types of lipid are there?
1) Triglycerides
2)Phospholipids
3) Steroids
What is each lipid type made of?
1) 3 fatty acid molecules + 1 glycerol molecule
2) 2 fatty acids + glycerol + phosphate
3) 4 fused rings
Describe what the solubility of lipids is in certain conditions
- Insoluble in water
- Soluble in organic solvents eg. ethanol
- Soluble in cell membrane as it controls what enters the cell
How are triglycerides formed?
3 condensation reactions
What are the products of the condensation reaction of a triglyceride?
1 triglyceride molecule and 3 water molecules
What bonds form between the H of glycerol and OH of the fatty acid?
Ester bonds
What does R on a triglyceride refer to?
Hydrocarbon chain
Describe how an ester bond is formed between a glycerol and a fatty acid tail. What is this process called?
A condensation reaction occurs between the OH of the carboxyl group (COOH) of the fatty acid and the H of
the OH of the glycerol molecule which removes one water molecule and forms an ester bond. Process is called
esterification
What are the 2 types of R group?
Saturated and unsaturated
What is a saturated R group?
Hydrocarbon chain with no double bonds between C atoms
What is an unsaturated R group?
,3|Page
Hydrocarbon chain with at least one double bonds between C atoms
What is the shape of an unsaturated R group?
Kinked due to the double bond
What state is saturated triglyceride at room temperature and why?
Solid as the straight chains lie on top of each other
What is the purpose of a triglyceride?
Storage of energy as it contains lots of chemical energy
What is a monounsaturated fatty acid and what is it's state?
One double bond between C atoms ∴ liquid at room temperature as they cannot pack closely together
What is a polyunsaturated fatty acid?
More than one double bond between C atoms
What is the structure of each type of Cis and trans unsaturated fats and explain their shape?
Cis: H atoms on same side of double bond ∴ there is a kink in the chain
Trans: H atoms on opposite sides of the double bond ∴ no kink
Describe how the structure of triglycerides relates to their function
- High ratio of energy storing C-H bonds : C atoms so store energy
- Low mass : energy ratio so can store lots of energy in small spaces
- Large and polar ∴ insoluble so storage in cells not affected by water potential or osmosis
- Release H2O when oxidised so important source of water especially for animals living in dry desert
Phospholipid
a) What is the function of a it?
b) What does it allow to diffuse?
a) It is a lipid that forms a bilayer to make up cell membranes
b) Non-polar / small molecules
What is the purpose of the arrangement of the phospholipid bilayer?
To avoid water soluble substance from entering the cell
Describe how the structure of phospholipids relates to their function
- Phosphate heads are polar/hydrophilic so are attracted to water ∴ orient to aqueous environment either side of
membrane
, 4|Page
- Fatty acid tails are nonpolar/hydrophobic so are repelled by water ∴ orient to interior of membrane
- Can combine with carbohydrates to form glycolipids which are important in cell-recognition
What bonds bond the phosphate group and fatty acids to the glycerol?
Ester bonds
What do all fatty acid molecules have?
- Carboxylic acid: COOH
- Hydrocarbon chain
- Methyl group: CH3
What are some roles of lipids?
EW PETC
- Energy: oxidation releases energy (more than carbohydrates)
- Membranes: phospholipid bilayer
- Electrical insulation (nerves): myelin sheath
- Thermal insulation: subcutaneous fat (underneath the skin) eg. blubber on seals
- Waterproofing: birds (hunting on water need to remain dry), leaves (to avoid transpiration, waxy cuticle made
of lipids), skin
- Cushioning of vital organs: surrounding organs such as liver and kidneys
Describe the mechanism of waterproofing
- Lipids are hydrophobic so repel water
- Oily secretions from sebaceous glands on skin of mammals prevent fur and hair becoming waterlogged
Describe how lipids can be used in insulation
- Lipids are poor conductors of heat and hydrophilic ions
- Triglycerides are stores in adipose tissue under skin in subcutaneous fat
- ... to insulate body
- Adipose tissue has limited blood supply to further reduce heat loss
- Myelin wrapped around axons of neurons to insulate fibres and prevent movement of K+ and Na+, gives rise
to saltatory conduction which speeds up the conduction of nerve impulses
Describe the chemical test for lipids
1) Cut up a small sample of the food you want to test
