AQA GCSE Biology - Paper 1 questions and
100% solutions 2025
What does a nucleus do? - Answer It contains genetic material and controls the activities of the cell
What does cytoplasm do? - Answer It's a gel-like substance where most of the chemical reactions
happen. It contains enzymes that control these chemical reactions
What does a cell membrane do? - Answer It holds the cell together and controls what goes in and out
What do mitochondria do? - Answer These are where most of the reactions for aerobic respiration
occur. Respiration transfers energy that the cell needs to work
What do ribosomes do? - Answer This is where protein synthesis takes place - where proteins are made
in the cell
What do cell walls do? - Answer They are made of cellulose and they support and strengthen the cell
What does a vacuole do? - Answer It contains cell sap and helps maintain the shape of the cell
What do chloroplasts do? - Answer This is where photosynthesis occurs, which makes food for the plant.
They contain chlorophyll - a green pigment - which absorbs light needed for photosynthesis
What do bacterial cells contain? - Answer Cytoplasm, cell membrane, cell wall, flagella, ribosomes,
mitochondria, slime capsule, plasmids (small rings of DNA) and a single circular strand of DNA that floats
freely in the cytoplasm
What do bacterial cells NOT contain? - Answer A nucleus
What is the equation for magnification? - Answer Image size divided by actual size
,What is differentiation? - Answer The process by which a cell changes to become specialised for its job
What are undifferentiated cells called? - Answer Stem cells
What are sperm cells specialised for and how are they specialised? - Answer Reproduction - they
transport the male DNA to the female DNA
-It has a flagella and a streamlined head to help it swim towards the egg
-There are lots of mitochondria in the cell to provide the energy needed
-It carries enzymes in its head to help digest through the egg cell membranes
What are nerve cells specialised for and how are they specialised? - Answer Rapid signalling - they carry
electrical signals from one part of the body to another
-They are long to cover more distance
-They have branched connections at their ends to connect to other nerve cells and form a network
throughout the body
What are muscle cells specialised for and how are they specialised? - Answer Contraction - they need to
contract quickly
-They are long so they have space to contract
-They contain lots of mitochondria to generate the energy needed for contraction
What are root hair cells specialised for and how are they specialised? - Answer Absorbing water and
minerals
-They are cells on the surface of plant roots which grow into long hairs that stick out into the soil
-They have a large surface area for absorbing water and mineral ions from the soil
What are chromosomes? - Answer Coiled up lengths of DNA molecules that are found in the nuclei
What do multicellular organisms use mitosis for? - Answer To grow or replace cells that have been
damaged
,What are stem cells? - Answer They are undifferentiated cells that divide to produce lots more
undifferentiated cells. They then differentiate into different types of cell
Where are stem cells found? - Answer In early human embryos or the bone marrow of adults
What do embryonic stem cells do? - Answer 1) Used to replace faulty cells in sick people - insulin-
producing cells for diabetes and nerve cells for paralysed spinal injuries
2) Used to replace faulty blood cells
What is diffusion? - Answer Diffusion is the movement of particles from an area of high concentration to
an area of low concentration
Name the substances that can diffuse through cell membranes - Answer Glucose, water, oxygen and
amino acids
Name two substances that can't diffuse through cell membranes - Answer Protein and starch
What is osmosis? - Answer Osmosis is the passive movement of water molecules through a partially
permeable cell membrane from an area of high water concentration to an area of low water
concentration
What are the two main differences between active transport and diffusion? - Answer Active transport
uses energy whereas diffusion doesn't. Active transport goes against the concentration gradient
whereas diffusion goes along it
Adaptations of Exchange Surfaces - Answer 1) Large surface area - lots of substances can diffuse at once
2) Lots of blood vessels - to get stuff into and out of the blood quickly
3) Thin membrane - short distance for substances to diffuse
4) Often ventilated - air moves in & out
Give two ways that the villi in the small intestine are adapted for absorbing digested food - Answer 1) A
single layer of surface cells
, 2) A very good blood supply to assist quick absorption
Explain how the leaves are adapted to maximise the amount of carbon dioxide that gets into their cells -
Answer 1) The exchange surface in a leaf is covered in stomata which the carbon dioxide diffuses
through
2) The leaf has a flattened shape which increases the area of its exchange surface, therefore it's more
effective
3) The walls of the cells inside the leaf act as another exchange surface
4) The air spaces inside the leaf increase the area of the exchange surface which increases the chance
for carbon dioxide to enter the cells
What affects the rate of diffusion? - Answer Concentration gradient - the steeper the gradient, the faster
the rate
Temperature - the higher the temperature, the faster the rate (the particles have more energy thus
move around faster)
Surface area - the larger it is, the faster the rate
Diffusion distance - the shorter the distance, the faster the rate
Examples of active transport - Answer Plants = Root hairs absorb minerals and water. Each branch of a
root will be covered in tiny hairs, therefore increasing the surface area for the absorption of minerals
and water. The concentration of minerals is usually higher in the root hair cells than in the soil around
them, therefore they can't use diffusion for this process.
Animals = Glucose is taken in from the gut and from kidney tubules.
How are alveoli in the lungs specialised to maximise the diffusion of oxygen and carbon dioxide? -
Answer -an enormous surface area
-a moist lining for dissolving gases
-very thin walls
-a good blood supply
How do fish respire? - Answer -Water enters the fish through the mouth and passes out through the gills
-During this process, oxygen diffuses from the water into the blood in the gills and carbon dioxide
diffuses from the blood into the water
100% solutions 2025
What does a nucleus do? - Answer It contains genetic material and controls the activities of the cell
What does cytoplasm do? - Answer It's a gel-like substance where most of the chemical reactions
happen. It contains enzymes that control these chemical reactions
What does a cell membrane do? - Answer It holds the cell together and controls what goes in and out
What do mitochondria do? - Answer These are where most of the reactions for aerobic respiration
occur. Respiration transfers energy that the cell needs to work
What do ribosomes do? - Answer This is where protein synthesis takes place - where proteins are made
in the cell
What do cell walls do? - Answer They are made of cellulose and they support and strengthen the cell
What does a vacuole do? - Answer It contains cell sap and helps maintain the shape of the cell
What do chloroplasts do? - Answer This is where photosynthesis occurs, which makes food for the plant.
They contain chlorophyll - a green pigment - which absorbs light needed for photosynthesis
What do bacterial cells contain? - Answer Cytoplasm, cell membrane, cell wall, flagella, ribosomes,
mitochondria, slime capsule, plasmids (small rings of DNA) and a single circular strand of DNA that floats
freely in the cytoplasm
What do bacterial cells NOT contain? - Answer A nucleus
What is the equation for magnification? - Answer Image size divided by actual size
,What is differentiation? - Answer The process by which a cell changes to become specialised for its job
What are undifferentiated cells called? - Answer Stem cells
What are sperm cells specialised for and how are they specialised? - Answer Reproduction - they
transport the male DNA to the female DNA
-It has a flagella and a streamlined head to help it swim towards the egg
-There are lots of mitochondria in the cell to provide the energy needed
-It carries enzymes in its head to help digest through the egg cell membranes
What are nerve cells specialised for and how are they specialised? - Answer Rapid signalling - they carry
electrical signals from one part of the body to another
-They are long to cover more distance
-They have branched connections at their ends to connect to other nerve cells and form a network
throughout the body
What are muscle cells specialised for and how are they specialised? - Answer Contraction - they need to
contract quickly
-They are long so they have space to contract
-They contain lots of mitochondria to generate the energy needed for contraction
What are root hair cells specialised for and how are they specialised? - Answer Absorbing water and
minerals
-They are cells on the surface of plant roots which grow into long hairs that stick out into the soil
-They have a large surface area for absorbing water and mineral ions from the soil
What are chromosomes? - Answer Coiled up lengths of DNA molecules that are found in the nuclei
What do multicellular organisms use mitosis for? - Answer To grow or replace cells that have been
damaged
,What are stem cells? - Answer They are undifferentiated cells that divide to produce lots more
undifferentiated cells. They then differentiate into different types of cell
Where are stem cells found? - Answer In early human embryos or the bone marrow of adults
What do embryonic stem cells do? - Answer 1) Used to replace faulty cells in sick people - insulin-
producing cells for diabetes and nerve cells for paralysed spinal injuries
2) Used to replace faulty blood cells
What is diffusion? - Answer Diffusion is the movement of particles from an area of high concentration to
an area of low concentration
Name the substances that can diffuse through cell membranes - Answer Glucose, water, oxygen and
amino acids
Name two substances that can't diffuse through cell membranes - Answer Protein and starch
What is osmosis? - Answer Osmosis is the passive movement of water molecules through a partially
permeable cell membrane from an area of high water concentration to an area of low water
concentration
What are the two main differences between active transport and diffusion? - Answer Active transport
uses energy whereas diffusion doesn't. Active transport goes against the concentration gradient
whereas diffusion goes along it
Adaptations of Exchange Surfaces - Answer 1) Large surface area - lots of substances can diffuse at once
2) Lots of blood vessels - to get stuff into and out of the blood quickly
3) Thin membrane - short distance for substances to diffuse
4) Often ventilated - air moves in & out
Give two ways that the villi in the small intestine are adapted for absorbing digested food - Answer 1) A
single layer of surface cells
, 2) A very good blood supply to assist quick absorption
Explain how the leaves are adapted to maximise the amount of carbon dioxide that gets into their cells -
Answer 1) The exchange surface in a leaf is covered in stomata which the carbon dioxide diffuses
through
2) The leaf has a flattened shape which increases the area of its exchange surface, therefore it's more
effective
3) The walls of the cells inside the leaf act as another exchange surface
4) The air spaces inside the leaf increase the area of the exchange surface which increases the chance
for carbon dioxide to enter the cells
What affects the rate of diffusion? - Answer Concentration gradient - the steeper the gradient, the faster
the rate
Temperature - the higher the temperature, the faster the rate (the particles have more energy thus
move around faster)
Surface area - the larger it is, the faster the rate
Diffusion distance - the shorter the distance, the faster the rate
Examples of active transport - Answer Plants = Root hairs absorb minerals and water. Each branch of a
root will be covered in tiny hairs, therefore increasing the surface area for the absorption of minerals
and water. The concentration of minerals is usually higher in the root hair cells than in the soil around
them, therefore they can't use diffusion for this process.
Animals = Glucose is taken in from the gut and from kidney tubules.
How are alveoli in the lungs specialised to maximise the diffusion of oxygen and carbon dioxide? -
Answer -an enormous surface area
-a moist lining for dissolving gases
-very thin walls
-a good blood supply
How do fish respire? - Answer -Water enters the fish through the mouth and passes out through the gills
-During this process, oxygen diffuses from the water into the blood in the gills and carbon dioxide
diffuses from the blood into the water
