AQA GCSE Biology - Paper 1
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What does a nucleus do? -correct answer_It contains genetic material and
controls the activities of the cell What does cytoplasm do? -correct 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?
-correct answer_It holds the cell together and controls what goes in and out What
do mitochondria do? -correct 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? -correct answer_This is where protein synthesis takes
place - where proteins are made in the cell What do cell walls do? -correct
answer_They are made of cellulose and they support and strengthen the cell What
does a vacuole do? -correct answer_It contains cell sap and helps maintain the
shape of the cell What do chloroplasts do? -correct 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? -correct 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? -correct answer_A nucleus What is the equation for
magnification? -correct answer_Image size divided by actual size is differentiation?
-correct answer_The process by which a cell changes to become specialised for it
What s job What are undifferentiated cells called? -correct answer_Stem cells
What are sperm cells specialised for and how are they specialised? -correct
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? -correct 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? -correct 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? -correct
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?
-correct answer_Coiled up lengths of DNA molecules that are found in the nuclei
What do multicellular organisms use mitosis for? -correct answer_To grow or
replace cells that have been damaged What are stem cells? -correct 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?
-correct answer_In early human embryos or the bone marrow of adults What do
embryonic stem cells do? -correct 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? -correct
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 -correct answer_Glucose, water, oxygen and amino acids Name two
substances that can't diffuse through cell membranes -correct answer_Protein
and starch What is osmosis? -correct 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? -correct 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 -correct 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 -correct 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 -correct
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? -correct
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 -correct 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? -correct answer_-an enormous surface
area -a moist lining for dissolving gases -very thin walls -a good blood supply How
do fish respire? -correct 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
How are fish adapted for gas exchange? -correct answer_-Each gill is made up of
lots of gill filaments which create a large surface area for the exchange of gases
-Gill filaments are covered in lamellae which increase the surface even more -The
lamellae have lots of blood capillaries to speed up diffusion -The lamellae have a
thin surface layer of cells to minimise the diffusion distance -Blood flows through
the lamellae one way and water flows over in the opposite direction which
maintains a higher concentration gradient between the blood and the water -The
concentration of oxygen in the water is always higher than that in the blood to
maximise the amount of oxygen diffusion from the water into the blood Microscopy
Practical - Preparing the Slide -correct answer_1) Add a drop of water to the
middle of a clean slide 2) Cut up an onion & separate it out into layers. Use
tweezers to peel off some epidermal tissue from the bottom of one of the layers 3)
Using the tweezers, place the epidermal tissue into the water on the slide 4) Add a
drop of iodine solution - a stain used to highlight objects in a cell by adding colour
to them 5) Place a cover slip on top - stand the cover slip upright on the slide, next
to the water droplet. Then, carefully tilt & lower it so it covers the specimen. Try
not to get any air bubbles under there - there'll obstruct your view Microscopy
Practical - Using a Light Microscope -correct answer_1) Clip the slide you've
prepared onto the stage 2) Select the lowest-powered objective lens 3) Use the
coarse adjustment knob to move the stage up to just below the objective lens 4)
Look down the eyepiece. Use the coarse adjustment knob to move the stage
downwards until the image is roughly in focus 5) Adjust the focus with the fine
adjustment knob, until you get a clear image of what's on the slide Microscopy
Practical - Drawing Observations -correct answer_1) Draw what you see under the
microscope using a pencil with a sharp point 2) Make sure your drawing takes up
Save
What does a nucleus do? -correct answer_It contains genetic material and
controls the activities of the cell What does cytoplasm do? -correct 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?
-correct answer_It holds the cell together and controls what goes in and out What
do mitochondria do? -correct 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? -correct answer_This is where protein synthesis takes
place - where proteins are made in the cell What do cell walls do? -correct
answer_They are made of cellulose and they support and strengthen the cell What
does a vacuole do? -correct answer_It contains cell sap and helps maintain the
shape of the cell What do chloroplasts do? -correct 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? -correct 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? -correct answer_A nucleus What is the equation for
magnification? -correct answer_Image size divided by actual size is differentiation?
-correct answer_The process by which a cell changes to become specialised for it
What s job What are undifferentiated cells called? -correct answer_Stem cells
What are sperm cells specialised for and how are they specialised? -correct
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? -correct 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? -correct 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? -correct
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?
-correct answer_Coiled up lengths of DNA molecules that are found in the nuclei
What do multicellular organisms use mitosis for? -correct answer_To grow or
replace cells that have been damaged What are stem cells? -correct 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?
-correct answer_In early human embryos or the bone marrow of adults What do
embryonic stem cells do? -correct 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? -correct
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 -correct answer_Glucose, water, oxygen and amino acids Name two
substances that can't diffuse through cell membranes -correct answer_Protein
and starch What is osmosis? -correct 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? -correct 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 -correct 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 -correct 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 -correct
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? -correct
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 -correct 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? -correct answer_-an enormous surface
area -a moist lining for dissolving gases -very thin walls -a good blood supply How
do fish respire? -correct 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
How are fish adapted for gas exchange? -correct answer_-Each gill is made up of
lots of gill filaments which create a large surface area for the exchange of gases
-Gill filaments are covered in lamellae which increase the surface even more -The
lamellae have lots of blood capillaries to speed up diffusion -The lamellae have a
thin surface layer of cells to minimise the diffusion distance -Blood flows through
the lamellae one way and water flows over in the opposite direction which
maintains a higher concentration gradient between the blood and the water -The
concentration of oxygen in the water is always higher than that in the blood to
maximise the amount of oxygen diffusion from the water into the blood Microscopy
Practical - Preparing the Slide -correct answer_1) Add a drop of water to the
middle of a clean slide 2) Cut up an onion & separate it out into layers. Use
tweezers to peel off some epidermal tissue from the bottom of one of the layers 3)
Using the tweezers, place the epidermal tissue into the water on the slide 4) Add a
drop of iodine solution - a stain used to highlight objects in a cell by adding colour
to them 5) Place a cover slip on top - stand the cover slip upright on the slide, next
to the water droplet. Then, carefully tilt & lower it so it covers the specimen. Try
not to get any air bubbles under there - there'll obstruct your view Microscopy
Practical - Using a Light Microscope -correct answer_1) Clip the slide you've
prepared onto the stage 2) Select the lowest-powered objective lens 3) Use the
coarse adjustment knob to move the stage up to just below the objective lens 4)
Look down the eyepiece. Use the coarse adjustment knob to move the stage
downwards until the image is roughly in focus 5) Adjust the focus with the fine
adjustment knob, until you get a clear image of what's on the slide Microscopy
Practical - Drawing Observations -correct answer_1) Draw what you see under the
microscope using a pencil with a sharp point 2) Make sure your drawing takes up
