AQA GCSE Biology - Paper 1GRADE A+
GURANTEED
What does a nucleus do?
It contains genetic material and controls the activities of the cell
What does cytoplasm do?
It's a gel-like substance where most of the chemical reactions happen.
It contains enzymes that control these chemical reactions
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What does a cell membrane do?
It holds the cell together and controls what goes in and out
What do mitochondria do?
These are where most of the reactions for aerobic respiration occur.
Respiration transfers energy that the cell needs to work
What do ribosomes do?
This is where protein synthesis takes place - where proteins are made
in the cell
What do cell walls do?
They are made of cellulose and they support and strengthen the cell
What does a vacuole do?
It contains cell sap and helps maintain the shape of the cell
What do chloroplasts do?
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?
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?
A nucleus
What is the equation for magnification?
Image size divided by actual size
What is differentiation?
The process by which a cell changes to become specialised for its job
What are undifferentiated cells called?
Stem cells
What are sperm cells specialised for and how are they specialised?
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?
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?
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?
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?
Coiled up lengths of DNA molecules that are found in the nuclei
What do multicellular organisms use mitosis for?
To grow or replace cells that have been damaged
What are stem cells?
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?
In early human embryos or the bone marrow of adults
What do embryonic stem cells do?
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?
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
Glucose, water, oxygen and amino acids
Name two substances that can't diffuse through cell membranes
Protein and starch
What is osmosis?
, 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?
Active transport uses energy whereas diffusion doesn't. Active
transport goes against the concentration gradient whereas diffusion
goes along it
Adaptations of Exchange Surfaces
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
1) A single layer of surface cells
2) A very good blood supply to assist quick absorption
We have an expert-written solution to this problem!
Explain how the leaves are adapted to maximise the amount of carbon
dioxide that gets into their cells
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
We have an expert-written solution to this problem!
What affects the rate of diffusion?
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
Plants = Root hairs absorb minerals and water. Each branch of a root
will be covered in tiny hairs, therefore increasing the surface area
GURANTEED
What does a nucleus do?
It contains genetic material and controls the activities of the cell
What does cytoplasm do?
It's a gel-like substance where most of the chemical reactions happen.
It contains enzymes that control these chemical reactions
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What does a cell membrane do?
It holds the cell together and controls what goes in and out
What do mitochondria do?
These are where most of the reactions for aerobic respiration occur.
Respiration transfers energy that the cell needs to work
What do ribosomes do?
This is where protein synthesis takes place - where proteins are made
in the cell
What do cell walls do?
They are made of cellulose and they support and strengthen the cell
What does a vacuole do?
It contains cell sap and helps maintain the shape of the cell
What do chloroplasts do?
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?
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?
A nucleus
What is the equation for magnification?
Image size divided by actual size
What is differentiation?
The process by which a cell changes to become specialised for its job
What are undifferentiated cells called?
Stem cells
What are sperm cells specialised for and how are they specialised?
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?
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?
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?
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?
Coiled up lengths of DNA molecules that are found in the nuclei
What do multicellular organisms use mitosis for?
To grow or replace cells that have been damaged
What are stem cells?
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?
In early human embryos or the bone marrow of adults
What do embryonic stem cells do?
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?
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
Glucose, water, oxygen and amino acids
Name two substances that can't diffuse through cell membranes
Protein and starch
What is osmosis?
, 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?
Active transport uses energy whereas diffusion doesn't. Active
transport goes against the concentration gradient whereas diffusion
goes along it
Adaptations of Exchange Surfaces
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
1) A single layer of surface cells
2) A very good blood supply to assist quick absorption
We have an expert-written solution to this problem!
Explain how the leaves are adapted to maximise the amount of carbon
dioxide that gets into their cells
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
We have an expert-written solution to this problem!
What affects the rate of diffusion?
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
Plants = Root hairs absorb minerals and water. Each branch of a root
will be covered in tiny hairs, therefore increasing the surface area
