A level biology paper 1 exam questions and
answers 2026\2027 A+ Grade
Has a similar shape to the substrate so will compete with it by binding to the active site. No enzyme-
substrate complexes are formed. The effect can be reduced if the concentration of substrate increases
- correct answer competitive inhibition
binds to a site on the enzyme that is not the active site. This prevents enzyme-substrate complexes
being formed as it changes the shape of the enzyme and reduces the binding of enzyme to substrate.
The effect can't be reduced by adding more substrate.
- correct answer non-competitive inhibitor
The 3D structure means substrate is complementary to enzyme so it will only catalyse that reaction to
form an enzyme-substrate complex. The induced fit means the active site changes shape to get a better
fit of the substrate. Enzymes are catalysts so lower the activation energy slowing reactions to take place
at body temp
- correct answer Why can enzymes lower the body temp
The cell is unable to change shape as it has a cell wall made of murin (bacteria)
- correct answer Why does E coil not have cholesterol
Produces fatty acids
- correct answer Hydrolysis of lipids
- Fatty acids used to make phospholipids. Phospholipids in the membrane
- Fatty acids respire to release energy. Energy used for cell production
- correct answer Uses of fatty acids in the formation of new calls
- it's circular
- No introns
,- No histones
- correct answer DNA in prokaryotic cells
To allow light to go through. It's easier to penetrate when it's thin and allows a single layer of cells to be
viewed
- correct answer Why must the specimen when looking through a light microscope be cut thin
Deoxyribose
- correct answer Name of sugar in a DNA molecule
Introns. For example start/stop code
- correct answer What are non coding regions called and what do they do
Dense/ heavy organelles/ cells are at the bottom of the tube. When centrifuged the liquid is removed
- correct answer How does centrifuge work
Place leaf tissue in ice-cold, isotonic and buffered solution
Then place cell in homogeniser room remove debris and break open the cell
- correct answer What must cell be placed in when doing cell fractionation
Processes and packages proteins
- correct answer Golgi apparatus
has lots of ribosomes on it to make protein
- correct answer RER
Hydrophobic tails point inwards. Hydrophilic heads are on the outside.
This forms a phospholipid bilayer
- correct answer Describe how phospholipids are arranged in the plasma membrane
Add a drop of water
Place plant tissue onto slide
,Add a stain-iodine solution
Place a coverslip on top with a minted needle
- correct answer How to temporary mount slide for plant tissue
nucleus and mitochondria
- correct answer What does a prokaryotic cell lack?
The chromosomes are pulled to opposite poles
The v shape shows sister chromatids being pulled at their centromeres
- correct answer How do you know if a cell is in anaphase
chromosomes condense and become visible
- correct answer What happens in prophase?
Chromosomes line up along equator of spindle
- correct answer What happens in metaphase?
1. nuclear envelopes form around the identical sets of chromosomes at the two poles of the cell.
2. The chromosomes uncoil
3. Nucleoli appear in the two new nuclei.
- correct answer What happens during telophase
This is the step in the cell cycle when the cytoplasm divides in two.
- correct answer What happens during cytokinesis?
DNA replicates and synthesis of proteins
- correct answer What happens during interphase?
Prevents DNA replication so the nucleotides can't join together
- correct answer A drug inhibits DNA polymerase why is it effective against some cancers
, Water potential becomes lower. Water moves in by osmosis. Increased volume of water causes an
increase in pressure
- correct answer How is high pressure produced in the leaves
As the solubility of o2 falls. Less o2 flows over the hills so the blood oxygen concentration is lower. The
ventilation rate increased to maintain the flow of o2. A concentration gradient is maintained
- correct answer explain the advantage to the fish of the change in its rate of ventilation.
The walls of bronchi has lost elasticity so less recoil
- correct answer People who have been fire-breathers for many years often find they cannot breathe
out properly. Explain why.
Increased metabolism. Less o2 dissolved in water.
- correct answer The volume of water passing over the gills increases if the temperature of the water
increases. Suggest why.
Into the trachea, bronchi then bronchioles.
Down a pressure gradient
Down a concentration gradient
Across alveolar epithelium
- correct answer Describe how oxygen in the air reaches capillaries surrounding alveoli in the lungs.
Details of breathing are not required.
The walls of the bronchi/ bronchioles contract. More mucus is secreted. The diameter is reduced. Less
air is breathed out. Airflow is reduced
- correct answer How is air vol reduced for people who have Asthma
Joins nucleotides together
- correct answer What does DNA polymerase do in DNA replication
Deoxyribose
- correct answer Pentose sugar in DNA
answers 2026\2027 A+ Grade
Has a similar shape to the substrate so will compete with it by binding to the active site. No enzyme-
substrate complexes are formed. The effect can be reduced if the concentration of substrate increases
- correct answer competitive inhibition
binds to a site on the enzyme that is not the active site. This prevents enzyme-substrate complexes
being formed as it changes the shape of the enzyme and reduces the binding of enzyme to substrate.
The effect can't be reduced by adding more substrate.
- correct answer non-competitive inhibitor
The 3D structure means substrate is complementary to enzyme so it will only catalyse that reaction to
form an enzyme-substrate complex. The induced fit means the active site changes shape to get a better
fit of the substrate. Enzymes are catalysts so lower the activation energy slowing reactions to take place
at body temp
- correct answer Why can enzymes lower the body temp
The cell is unable to change shape as it has a cell wall made of murin (bacteria)
- correct answer Why does E coil not have cholesterol
Produces fatty acids
- correct answer Hydrolysis of lipids
- Fatty acids used to make phospholipids. Phospholipids in the membrane
- Fatty acids respire to release energy. Energy used for cell production
- correct answer Uses of fatty acids in the formation of new calls
- it's circular
- No introns
,- No histones
- correct answer DNA in prokaryotic cells
To allow light to go through. It's easier to penetrate when it's thin and allows a single layer of cells to be
viewed
- correct answer Why must the specimen when looking through a light microscope be cut thin
Deoxyribose
- correct answer Name of sugar in a DNA molecule
Introns. For example start/stop code
- correct answer What are non coding regions called and what do they do
Dense/ heavy organelles/ cells are at the bottom of the tube. When centrifuged the liquid is removed
- correct answer How does centrifuge work
Place leaf tissue in ice-cold, isotonic and buffered solution
Then place cell in homogeniser room remove debris and break open the cell
- correct answer What must cell be placed in when doing cell fractionation
Processes and packages proteins
- correct answer Golgi apparatus
has lots of ribosomes on it to make protein
- correct answer RER
Hydrophobic tails point inwards. Hydrophilic heads are on the outside.
This forms a phospholipid bilayer
- correct answer Describe how phospholipids are arranged in the plasma membrane
Add a drop of water
Place plant tissue onto slide
,Add a stain-iodine solution
Place a coverslip on top with a minted needle
- correct answer How to temporary mount slide for plant tissue
nucleus and mitochondria
- correct answer What does a prokaryotic cell lack?
The chromosomes are pulled to opposite poles
The v shape shows sister chromatids being pulled at their centromeres
- correct answer How do you know if a cell is in anaphase
chromosomes condense and become visible
- correct answer What happens in prophase?
Chromosomes line up along equator of spindle
- correct answer What happens in metaphase?
1. nuclear envelopes form around the identical sets of chromosomes at the two poles of the cell.
2. The chromosomes uncoil
3. Nucleoli appear in the two new nuclei.
- correct answer What happens during telophase
This is the step in the cell cycle when the cytoplasm divides in two.
- correct answer What happens during cytokinesis?
DNA replicates and synthesis of proteins
- correct answer What happens during interphase?
Prevents DNA replication so the nucleotides can't join together
- correct answer A drug inhibits DNA polymerase why is it effective against some cancers
, Water potential becomes lower. Water moves in by osmosis. Increased volume of water causes an
increase in pressure
- correct answer How is high pressure produced in the leaves
As the solubility of o2 falls. Less o2 flows over the hills so the blood oxygen concentration is lower. The
ventilation rate increased to maintain the flow of o2. A concentration gradient is maintained
- correct answer explain the advantage to the fish of the change in its rate of ventilation.
The walls of bronchi has lost elasticity so less recoil
- correct answer People who have been fire-breathers for many years often find they cannot breathe
out properly. Explain why.
Increased metabolism. Less o2 dissolved in water.
- correct answer The volume of water passing over the gills increases if the temperature of the water
increases. Suggest why.
Into the trachea, bronchi then bronchioles.
Down a pressure gradient
Down a concentration gradient
Across alveolar epithelium
- correct answer Describe how oxygen in the air reaches capillaries surrounding alveoli in the lungs.
Details of breathing are not required.
The walls of the bronchi/ bronchioles contract. More mucus is secreted. The diameter is reduced. Less
air is breathed out. Airflow is reduced
- correct answer How is air vol reduced for people who have Asthma
Joins nucleotides together
- correct answer What does DNA polymerase do in DNA replication
Deoxyribose
- correct answer Pentose sugar in DNA
