COMPREHENSIVE AQA AS BIOLOGY
REVISION 2025 UPDATED
QUESTIONS WITH VERIFIED
ACTUAL ANSWERS
What are biological molecules? - CORRECT ANSWER>>>molecules made and used
by living organisms e.g. Carbohydrates, Proteins, Lipids, DNA, ATP, Water, Inorganic
Ions
What are the functions of carbohydrates? - CORRECT ANSWER>>>energy source
(glucose in respiration)
energy store (starch in plants, glycogen in animals)
structure (cellulose in cell wall of plants)
What are the building blocks for carbohydrates called? - CORRECT
ANSWER>>>monosaccharides
Example of monosaccharides? - CORRECT ANSWER>>>glucose (alpha and beta),
galactose, fructose
Formula for monosaccharides? - CORRECT ANSWER>>>C6H12O6 (isomers = same
formula but different arrangement)
Difference between alpha and beta glucose? - CORRECT ANSWER>>>one Carbon 1,
alpha glucose has a OH group on the bottom and beta glucose has a OH group on the
top
How are monosaccharides joined together? - CORRECT ANSWER>>>condensation
reaction (removing water) - between 2 OH groups
Bond in carbohydrate? - CORRECT ANSWER>>>glycosidic bond (1,4 - between
carbon 1 and carbon 4)
Example of disaccharides? - CORRECT ANSWER>>>glucose + glucose = maltose,
glucose + galactose = lactose, glucose + fructose = sucrose
Formula for disaccharides? - CORRECT ANSWER>>>C12H22O11
How are polymers separated? - CORRECT ANSWER>>>hydrolysis (add water)
1
,What is a polysaccharide? - CORRECT ANSWER>>>many monosacharrides joined by
condensation reaction/glycosidic bonds
Example of polysaccharides? - CORRECT ANSWER>>>Starch (long chain of alpha
glucose) which is energy store in plants
Glycogen (long chain of alpha glucose) which is energy store in animals
Cellulose (long chain of beta glucose) which makes cell wall in plants
What are Polysaccharides? - CORRECT ANSWER>>>carbohydrates
made of a long chain of monosaccharides joined by condensation reaction/glycosidic
bonds
3 examples: Starch, Glycogen, Cellulose
Starch & Glycogen used as Energy Stores (starch in plants, glycogen in animals), they
are made out of many alpha glucose which are used for respiration
Cellulose used to form Cell Wall in Plants, made out of many beta glucose
Structure of Starch? - CORRECT ANSWER>>>made from Amylose and Amylopectin
Amylose = long straight chain of alpha-glucose which is coiled
Amylopectin = straight chain of alpha-glucose with side branches (1,6-glycosidic bond)
Structure of Glycogen? - CORRECT ANSWER>>>straight chain of alpha-glucose (1,4-
glycosidic bond) with side branches (1,6-glycosidic bond)
Properties of Starch and Glycogen as energy stores? - CORRECT
ANSWER>>>Insoluble = do not affect water potential of the cell, do not diffuse out of
the cell
Coiled/Branched = compact, more can fit into a cell
Branched/Chained = glucose removed from the end
Structure of Cellulose? - CORRECT ANSWER>>>β-glucose arranged in a straight
chain (each alternative β-glucose is rotated 180 degrees) = cellulose straight chain
many cellulose chains are cross linked by hydrogen bonds to form microfibrils
many microfibrils are cross linked to form marcrofibrils
forms structure of cell wall
strong material (prevents plant cell from bursting or shrinking)
test for starch - CORRECT ANSWER>>>add iodine, turns blue/black
Test for reducing sugar? - CORRECT ANSWER>>>heat with benedicts, turns brick red
2
,Test for non-reducing sugar? - CORRECT ANSWER>>>heat with benedicts - no
change
therefore, add dilute hydrochloric acid (hydrolyses glycosidic bond)
then add sodium hydrogencarbonate (neutralises solution)
heat with benedict - turns brick red
What are 2 types of proteins? - CORRECT ANSWER>>>Globular and Fibrous
What are globular proteins? - CORRECT ANSWER>>>soluble proteins with a specific
3D shape e.g. enzymes, hormones, antibodies, haemoglobin
What are fibrous proteins? - CORRECT ANSWER>>>strong/insoluble/inflexible material
e.g. collagen and keratin
What are the building blocks for proteins? - CORRECT ANSWER>>>amino acids
Structure of amino acid? - CORRECT ANSWER>>>central carbon, carboxyl group to
the right (COOH), amine group to the left (NH2), hydrogen above and R group below
How do amino acids differ? - CORRECT ANSWER>>>have different R groups e.g.
glycine has a hydrogen in its R group - simplest amino acid
How are amino acids joined together? - CORRECT ANSWER>>>by condensation
reaction between the carboxyl group of one and amine group of another, leaves a bond
between carbon & nitrogen (called a peptide bond) forming a dipeptide
Define primary, secondary, tertiary, quaternary structure? - CORRECT
ANSWER>>>Primary = sequence of AA, polypeptide chain (held by peptide bonds)
Secondary = the primary structure (polypeptide chain) coils to form a helix, held by
hydrogen bonds
Tertiary = secondary structure folds again to form final 3d shape, held together by
hydrogen/ionic/disulfide bonds
Quaternary = made of more then one polypeptide chain
Examples of quaternary structure proteins? - CORRECT ANSWER>>>collagen (3
chains), antibodies (3 chains), haemoglobin (4 chains)
Structure of collagen? - CORRECT ANSWER>>>strong material, used to build
tendons/ligaments/connective tissues
primary structure mainly made up of glycine (simplest amino acid)
secondary structure forms a tight coil (not much branching due to glycine)
tertiary structure coils again
3
, quaternary structure made from 3 tertiary structures wrapped around each other like
rope
= a collagen molecule
many of these collagen molecules make the tendons/ligaments/connective tissues
Test for protein? - CORRECT ANSWER>>>add biuret, turns purple
What is an enzyme? - CORRECT ANSWER>>>a biological catalyst (substance that
speeds up the rate of reaction without being used up - lowers activation energy)
What makes an enzyme specific? - CORRECT ANSWER>>>has a specific active site
shape, only complementary substrates can bind to the active site to form enzyme-
substrate complexes
Lock and Key Model vs Induced Fit Model? - CORRECT ANSWER>>>LK = active site
shape is rigid, only exactly complementary substrates can bind to form ES complexes
IF = active site changes shape, the substrate binds to the active site - the active site
changes shape so the substrate fits exactly forming an ES complex
Affect of substrate concentration on enzyme activity? - CORRECT
ANSWER>>>increase substrate concentration, increases chance of successful
collisions, increase chance of forming an ES complex, increase rate of reaction
this continues until all the enzyme's active sites are full/saturated = maximum rate of
reaction
Affect of enzyme concentration on enzyme activity? - CORRECT ANSWER>>>increase
enzyme concentration, increases chance of successful collisions, increase chance of
forming an ES complex, increase rate of reaction
this continues until all the substrates are used up = maximum rate of reaction
Affect of temperature on enzyme activity? - CORRECT ANSWER>>>as temperature
increases
the kinetic energy increases
the molecules move faster
increase chance of successful collisions
increase chance of forming ES complex
increase rate of reaction
4
REVISION 2025 UPDATED
QUESTIONS WITH VERIFIED
ACTUAL ANSWERS
What are biological molecules? - CORRECT ANSWER>>>molecules made and used
by living organisms e.g. Carbohydrates, Proteins, Lipids, DNA, ATP, Water, Inorganic
Ions
What are the functions of carbohydrates? - CORRECT ANSWER>>>energy source
(glucose in respiration)
energy store (starch in plants, glycogen in animals)
structure (cellulose in cell wall of plants)
What are the building blocks for carbohydrates called? - CORRECT
ANSWER>>>monosaccharides
Example of monosaccharides? - CORRECT ANSWER>>>glucose (alpha and beta),
galactose, fructose
Formula for monosaccharides? - CORRECT ANSWER>>>C6H12O6 (isomers = same
formula but different arrangement)
Difference between alpha and beta glucose? - CORRECT ANSWER>>>one Carbon 1,
alpha glucose has a OH group on the bottom and beta glucose has a OH group on the
top
How are monosaccharides joined together? - CORRECT ANSWER>>>condensation
reaction (removing water) - between 2 OH groups
Bond in carbohydrate? - CORRECT ANSWER>>>glycosidic bond (1,4 - between
carbon 1 and carbon 4)
Example of disaccharides? - CORRECT ANSWER>>>glucose + glucose = maltose,
glucose + galactose = lactose, glucose + fructose = sucrose
Formula for disaccharides? - CORRECT ANSWER>>>C12H22O11
How are polymers separated? - CORRECT ANSWER>>>hydrolysis (add water)
1
,What is a polysaccharide? - CORRECT ANSWER>>>many monosacharrides joined by
condensation reaction/glycosidic bonds
Example of polysaccharides? - CORRECT ANSWER>>>Starch (long chain of alpha
glucose) which is energy store in plants
Glycogen (long chain of alpha glucose) which is energy store in animals
Cellulose (long chain of beta glucose) which makes cell wall in plants
What are Polysaccharides? - CORRECT ANSWER>>>carbohydrates
made of a long chain of monosaccharides joined by condensation reaction/glycosidic
bonds
3 examples: Starch, Glycogen, Cellulose
Starch & Glycogen used as Energy Stores (starch in plants, glycogen in animals), they
are made out of many alpha glucose which are used for respiration
Cellulose used to form Cell Wall in Plants, made out of many beta glucose
Structure of Starch? - CORRECT ANSWER>>>made from Amylose and Amylopectin
Amylose = long straight chain of alpha-glucose which is coiled
Amylopectin = straight chain of alpha-glucose with side branches (1,6-glycosidic bond)
Structure of Glycogen? - CORRECT ANSWER>>>straight chain of alpha-glucose (1,4-
glycosidic bond) with side branches (1,6-glycosidic bond)
Properties of Starch and Glycogen as energy stores? - CORRECT
ANSWER>>>Insoluble = do not affect water potential of the cell, do not diffuse out of
the cell
Coiled/Branched = compact, more can fit into a cell
Branched/Chained = glucose removed from the end
Structure of Cellulose? - CORRECT ANSWER>>>β-glucose arranged in a straight
chain (each alternative β-glucose is rotated 180 degrees) = cellulose straight chain
many cellulose chains are cross linked by hydrogen bonds to form microfibrils
many microfibrils are cross linked to form marcrofibrils
forms structure of cell wall
strong material (prevents plant cell from bursting or shrinking)
test for starch - CORRECT ANSWER>>>add iodine, turns blue/black
Test for reducing sugar? - CORRECT ANSWER>>>heat with benedicts, turns brick red
2
,Test for non-reducing sugar? - CORRECT ANSWER>>>heat with benedicts - no
change
therefore, add dilute hydrochloric acid (hydrolyses glycosidic bond)
then add sodium hydrogencarbonate (neutralises solution)
heat with benedict - turns brick red
What are 2 types of proteins? - CORRECT ANSWER>>>Globular and Fibrous
What are globular proteins? - CORRECT ANSWER>>>soluble proteins with a specific
3D shape e.g. enzymes, hormones, antibodies, haemoglobin
What are fibrous proteins? - CORRECT ANSWER>>>strong/insoluble/inflexible material
e.g. collagen and keratin
What are the building blocks for proteins? - CORRECT ANSWER>>>amino acids
Structure of amino acid? - CORRECT ANSWER>>>central carbon, carboxyl group to
the right (COOH), amine group to the left (NH2), hydrogen above and R group below
How do amino acids differ? - CORRECT ANSWER>>>have different R groups e.g.
glycine has a hydrogen in its R group - simplest amino acid
How are amino acids joined together? - CORRECT ANSWER>>>by condensation
reaction between the carboxyl group of one and amine group of another, leaves a bond
between carbon & nitrogen (called a peptide bond) forming a dipeptide
Define primary, secondary, tertiary, quaternary structure? - CORRECT
ANSWER>>>Primary = sequence of AA, polypeptide chain (held by peptide bonds)
Secondary = the primary structure (polypeptide chain) coils to form a helix, held by
hydrogen bonds
Tertiary = secondary structure folds again to form final 3d shape, held together by
hydrogen/ionic/disulfide bonds
Quaternary = made of more then one polypeptide chain
Examples of quaternary structure proteins? - CORRECT ANSWER>>>collagen (3
chains), antibodies (3 chains), haemoglobin (4 chains)
Structure of collagen? - CORRECT ANSWER>>>strong material, used to build
tendons/ligaments/connective tissues
primary structure mainly made up of glycine (simplest amino acid)
secondary structure forms a tight coil (not much branching due to glycine)
tertiary structure coils again
3
, quaternary structure made from 3 tertiary structures wrapped around each other like
rope
= a collagen molecule
many of these collagen molecules make the tendons/ligaments/connective tissues
Test for protein? - CORRECT ANSWER>>>add biuret, turns purple
What is an enzyme? - CORRECT ANSWER>>>a biological catalyst (substance that
speeds up the rate of reaction without being used up - lowers activation energy)
What makes an enzyme specific? - CORRECT ANSWER>>>has a specific active site
shape, only complementary substrates can bind to the active site to form enzyme-
substrate complexes
Lock and Key Model vs Induced Fit Model? - CORRECT ANSWER>>>LK = active site
shape is rigid, only exactly complementary substrates can bind to form ES complexes
IF = active site changes shape, the substrate binds to the active site - the active site
changes shape so the substrate fits exactly forming an ES complex
Affect of substrate concentration on enzyme activity? - CORRECT
ANSWER>>>increase substrate concentration, increases chance of successful
collisions, increase chance of forming an ES complex, increase rate of reaction
this continues until all the enzyme's active sites are full/saturated = maximum rate of
reaction
Affect of enzyme concentration on enzyme activity? - CORRECT ANSWER>>>increase
enzyme concentration, increases chance of successful collisions, increase chance of
forming an ES complex, increase rate of reaction
this continues until all the substrates are used up = maximum rate of reaction
Affect of temperature on enzyme activity? - CORRECT ANSWER>>>as temperature
increases
the kinetic energy increases
the molecules move faster
increase chance of successful collisions
increase chance of forming ES complex
increase rate of reaction
4
