GCSE AQA MAY 2023 HIGHER TRIPLE SCIENCE
BIOLOGY PAPER 1 MARK SCHEME
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 is mitosis? - ANSWER The stage of the cell cycle where the cell divides
What do multicellular organisms use mitosis for? - ANSWER To grow or replace
cells that have been damaged
Describe each stage of mitosis - ANSWER Prophase - The chromosomes shorten
and duplicate
Metaphase - The chromosomes line up on the equator of the cell
Anaphase - The chromosomes are pulled to the opposite ends of the cell. The
chromatids are now known as daughter cells.
Telophase - New membranes form around the daughter nuclei which becomes the
nuclei of the two new cells - the nucleus has divided. The cytoplasm and cell
membrane divide to create two daughter cells.
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
Where are stem cells found in plants? - ANSWER Meristems
, 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.
BIOLOGY PAPER 1 MARK SCHEME
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 is mitosis? - ANSWER The stage of the cell cycle where the cell divides
What do multicellular organisms use mitosis for? - ANSWER To grow or replace
cells that have been damaged
Describe each stage of mitosis - ANSWER Prophase - The chromosomes shorten
and duplicate
Metaphase - The chromosomes line up on the equator of the cell
Anaphase - The chromosomes are pulled to the opposite ends of the cell. The
chromatids are now known as daughter cells.
Telophase - New membranes form around the daughter nuclei which becomes the
nuclei of the two new cells - the nucleus has divided. The cytoplasm and cell
membrane divide to create two daughter cells.
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
Where are stem cells found in plants? - ANSWER Meristems
, 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.
