AQA GCSE Biology - Paper 12021/2022
What does a nucleus do? - answerIt contains genetic material and controls the activities
of the cell
What does cytoplasm do? - answerIt'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? - answerIt holds the cell together and controls what
goes in and out
What do mitochondria do? - answerThese are where most of the reactions for aerobic
respiration occur. Respiration transfers energy that the cell needs to work
What do ribosomes do? - answerThis is where protein synthesis takes place - where
proteins are made in the cell
What do cell walls do? - answerThey are made of cellulose and they support and
strengthen the cell
What does a vacuole do? - answerIt contains cell sap and helps maintain the shape of
the cell
What do chloroplasts do? - answerThis 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? - answerCytoplasm, 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? - answerA nucleus
What is the equation for magnification? - answerImage size divided by actual size
What is differentiation? - answerThe process by which a cell changes to become
specialised for its job
What are undifferentiated cells called? - answerStem cells
What are sperm cells specialised for and how are they specialised? -
answerReproduction - 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? - answerRapid
signalling - they carry electrical signals from one part of the body to another
,AQA GCSE Biology - Paper 12021/2022
-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? -
answerContraction - 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? -
answerAbsorbing 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? - answerCoiled up lengths of DNA molecules that are found in
the nuclei
What do multicellular organisms use mitosis for? - answerTo grow or replace cells that
have been damaged
What are stem cells? - answerThey are undifferentiated cells that divide to produce lots
more undifferentiated cells. They then differentiate into different types of cell
Where are stem cells found? - answerIn early human embryos or the bone marrow of
adults
What do embryonic stem cells do? - answer1) 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? - answerDiffusion 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 - answerGlucose, water,
oxygen and amino acids
Name two substances that can't diffuse through cell membranes - answerProtein and
starch
What is osmosis? - answerOsmosis 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
, AQA GCSE Biology - Paper 12021/2022
What are the two main differences between active transport and diffusion? -
answerActive transport uses energy whereas diffusion doesn't. Active transport goes
against the concentration gradient whereas diffusion goes along it
Adaptations of Exchange Surfaces - answer1) 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 - answer1) 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 - answer1) 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? - answerConcentration 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 - answerPlants = 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
What does a nucleus do? - answerIt contains genetic material and controls the activities
of the cell
What does cytoplasm do? - answerIt'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? - answerIt holds the cell together and controls what
goes in and out
What do mitochondria do? - answerThese are where most of the reactions for aerobic
respiration occur. Respiration transfers energy that the cell needs to work
What do ribosomes do? - answerThis is where protein synthesis takes place - where
proteins are made in the cell
What do cell walls do? - answerThey are made of cellulose and they support and
strengthen the cell
What does a vacuole do? - answerIt contains cell sap and helps maintain the shape of
the cell
What do chloroplasts do? - answerThis 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? - answerCytoplasm, 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? - answerA nucleus
What is the equation for magnification? - answerImage size divided by actual size
What is differentiation? - answerThe process by which a cell changes to become
specialised for its job
What are undifferentiated cells called? - answerStem cells
What are sperm cells specialised for and how are they specialised? -
answerReproduction - 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? - answerRapid
signalling - they carry electrical signals from one part of the body to another
,AQA GCSE Biology - Paper 12021/2022
-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? -
answerContraction - 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? -
answerAbsorbing 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? - answerCoiled up lengths of DNA molecules that are found in
the nuclei
What do multicellular organisms use mitosis for? - answerTo grow or replace cells that
have been damaged
What are stem cells? - answerThey are undifferentiated cells that divide to produce lots
more undifferentiated cells. They then differentiate into different types of cell
Where are stem cells found? - answerIn early human embryos or the bone marrow of
adults
What do embryonic stem cells do? - answer1) 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? - answerDiffusion 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 - answerGlucose, water,
oxygen and amino acids
Name two substances that can't diffuse through cell membranes - answerProtein and
starch
What is osmosis? - answerOsmosis 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
, AQA GCSE Biology - Paper 12021/2022
What are the two main differences between active transport and diffusion? -
answerActive transport uses energy whereas diffusion doesn't. Active transport goes
against the concentration gradient whereas diffusion goes along it
Adaptations of Exchange Surfaces - answer1) 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 - answer1) 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 - answer1) 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? - answerConcentration 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 - answerPlants = 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
