AQA GCSE Biology - Paper 1
Adaptations of Exchange Surfaces - ANS-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
\Aerobic respiration - ANS-Respiration using oxygen
Goes on constantly in plants and animals
Most of the reactions happen inside mitochondria
\Aerobic respiration equation - ANS-Glucose + oxygen --> carbon dioxide + water
\Anaerobic respiration - animals - ANS-Respiration without oxygen
Incomplete breakdown of glucose
Happens when your body can't supply enough oxygen to your muscles during vigorous
exercise
Doesn't transfer as much energy as aerobic respiration - glucose isn't fully oxidised
\Anaerobic respiration - plants & yeasts - ANS-In yeasts, it's called fermentation
Fermentation is used to make bread and alcohol drinks
\Anaerobic respiration equation - animals - ANS-Glucose --> lactic acid
\Anaerobic respiration equation - plants and yeasts - ANS-Glucose --> ethanol + carbon
dioxide
\Aspirin - ANS-Used as a painkiller & to lower fever
Developed from a chemical found in willow
\Avoiding Contamination - ANS-1) The Petri dishes & culture medium must be sterilised
before use (heating to a high temperature), to kill any unwanted microorganisms
2) If an inoculating loop is used to transfer the bacteria to the culture medium, it should be
sterilised first by passing it through a hot flame
3) After transferring the bacteria, the lid of the Petri dish should be lightly taped on - stops
any microorganisms from the air getting it
4) The Petri dish should be stored upside down - stops drops of condensation falling onto
the agar surface
\B-lymphocytes - white blood cells - ANS-Recognise foreign antigens on cells and produce
antibodies to lock onto the antigens so that the cells can be located and destroyed
The antibodies are specific to that type of antigen - they form a lock and key connection
\Benedict's Test - testing for sugars - ANS-1) Prepare a food sample & transfer 5cm³ to a test
tube
2) Prepare a water bath so that it's set to 75°C
3) Add some Benedict's solution to the test tube (about 10 drops) using a pipette
4) Place the test tube in the water bath using a test tube holder & leave it there for 5
minutes. Ensure the tube is pointing away from you
5) If the food sample contains a reducing sugar, the solution in the test tube will change from
the normal blue colour to green, yellow or brick-red - depends how much sugar is in the food
\Big Molecules - ANS-Starch
Proteins
Fats
,\Biuret Test - testing for proteins - ANS-1) Prepare a sample of your food & transfer 2cm³ of it
to a test tube
2) Add 2cm³ of biuret solution to the sample & mix the contents of the tube by gently shaking
it
3) If the food sample contains protein, the solution will change from blue to pink or purple
\Calculation - Rate of Reaction - ANS-Rate = 1000/time
\Chemical defences of plants - ANS-1) Antibacterial chemicals - these kill bacteria and are
found in mint plants and witch hazels
2) Poisons helped to deter herbivores from eating them e.g. tobacco plants, foxgloves and
deadly nightshade
\Cilia as a defence - ANS-Hair-like structures which waft the mucus up to the back of your
throat where it can be swallowed (and used to trap pathogens)
\Common symptoms of plant diseases - ANS-1) Stunted growth
2) Abnormal growths e.g. lumps
3) Spots on the leaves
4) Malformed stems or leaves
5) Patches of decay (rot)
6) Discolouration
\CONS of vaccinations - ANS-1) Sometimes they don't give you immunity
2) They can sometimes trigger bad reactions e.g. swelling, fevers, seizures - bad reactions
are very rare
\Digitalis - ANS-Used to treat heart conditions
Developed from a chemical found in foxgloves
\Disadvantages of Stem Cells - ANS-1) Stem cells grown in the lab may become
contaminated with a virus - this will be passed onto the patient & make them sicker
2) Some people think that human embryos shouldn't be used for experiments - each one is a
potential human life
3) Scientists should focus more on finding & developing other sources of stem cells
\Drinking as a risk factor - ANS-Drinking too much alcohol causes liver disease, affects brain
function and damages the nerve cells in the brain
\Drug testing - Stage 1 - ANS-Drugs are tested on human cells and tissues
However, human cells and tissue won't determine a drug's effectiveness against an entire
body system
\Drug testing - Stage 2 - ANS-Drugs are tested on live animals - at least two different
mammals
Tests for efficacy (whether it works), toxicity (how harmful it is) and to determine the right
dosage
\Drug testing - Stage 3 - ANS-Drugs are tested on human volunteers
1) Drug is tested on healthy volunteers at a low dosage - reveals any harmful side effects
2) Drug is tested on the sick people it is designed to treat - used to find the optimum dosage
3) The patients are randomly sorted into 2 groups - one group gets a placebo, the other gets
the actual drug
\Epidermal tissue - ANS-Covers the whole plant
\Example of an organ system - ANS-Digestive system - glands (pancreas and salivary
glands), stomach, liver, small intestine and large intestine
\Examples of active transport - ANS-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.
\Examples of tissues - ANS-Muscular tissue - contracts to move whatever it's attached to
Glandular tissue - makes and secretes chemicals like enzymes and hormones
Epithelial tissue - covers some parts of the human body e.g. the inside of the gut
\Explain how the leaves are adapted to maximise the amount of carbon dioxide that gets into
their cells - ANS-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
\Exposure to radiation as a risk factor - ANS-Cancer can be caused by exposure to ionising
radiation, a carcinogen (something that causes cancer)
\Financial Cost of Disease - ANS-1) Cost to the NHS of researching & treating these
diseases is huge
2) Families may have to move or adapt their home to help a family member with a disease
3) If a family member has to give up work or dies, the family's income will be reduced
4) Reduction in the number of people able to work can also affect a country's economy
\Fungi - ANS-Some fungi are single-celled
Other fungi have a body which is made up of hyphae - these grow & penetrate human skin &
the surface of plants
Hyphae can produce spores - can spread to other plants & animals
\Give two ways that the villi in the small intestine are adapted for absorbing digested food -
ANS-1) A single layer of surface cells
2) A very good blood supply to assist quick absorption
\Gonorrhoea - ANS-Bacterial disease
Sexually transmitted disease (STD) caused by sexual contact e.g. unprotected sex
Symptoms: pain when urinating; thick yellow/green discharge from the vagina/penis
Originally treated with penicillin - now some strains have become resistant to it
Treatment with antibiotics and using barrier methods of contraception (e.g. condoms) help
prevent the spread of it
\Greenhouses - carbon dioxide concentration - ANS-Paraffin heaters help increase the
concentration of carbon dioxide - as the paraffin burns, it creates carbon dioxide as a
by-product
\Greenhouses - light intensity - ANS-Artificial light is used after the sun goes down - gives
the plant more quality photosynthesis time
\Greenhouses - temperature - ANS-Help to trap the sun's heat and ensure the temperature
doesn't become a limiting factor
Heaters are used in winter to maintain a high temperature
Ventilation is used in summer to prevent the temperature increasing too much
\Guard cells - ANS-Control the opening and closing of the stomata
They don't open up at night as there is no sunlight
\Hairs and mucus as a defence - ANS-In your nose, they trap particles that contain
pathogens
Adaptations of Exchange Surfaces - ANS-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
\Aerobic respiration - ANS-Respiration using oxygen
Goes on constantly in plants and animals
Most of the reactions happen inside mitochondria
\Aerobic respiration equation - ANS-Glucose + oxygen --> carbon dioxide + water
\Anaerobic respiration - animals - ANS-Respiration without oxygen
Incomplete breakdown of glucose
Happens when your body can't supply enough oxygen to your muscles during vigorous
exercise
Doesn't transfer as much energy as aerobic respiration - glucose isn't fully oxidised
\Anaerobic respiration - plants & yeasts - ANS-In yeasts, it's called fermentation
Fermentation is used to make bread and alcohol drinks
\Anaerobic respiration equation - animals - ANS-Glucose --> lactic acid
\Anaerobic respiration equation - plants and yeasts - ANS-Glucose --> ethanol + carbon
dioxide
\Aspirin - ANS-Used as a painkiller & to lower fever
Developed from a chemical found in willow
\Avoiding Contamination - ANS-1) The Petri dishes & culture medium must be sterilised
before use (heating to a high temperature), to kill any unwanted microorganisms
2) If an inoculating loop is used to transfer the bacteria to the culture medium, it should be
sterilised first by passing it through a hot flame
3) After transferring the bacteria, the lid of the Petri dish should be lightly taped on - stops
any microorganisms from the air getting it
4) The Petri dish should be stored upside down - stops drops of condensation falling onto
the agar surface
\B-lymphocytes - white blood cells - ANS-Recognise foreign antigens on cells and produce
antibodies to lock onto the antigens so that the cells can be located and destroyed
The antibodies are specific to that type of antigen - they form a lock and key connection
\Benedict's Test - testing for sugars - ANS-1) Prepare a food sample & transfer 5cm³ to a test
tube
2) Prepare a water bath so that it's set to 75°C
3) Add some Benedict's solution to the test tube (about 10 drops) using a pipette
4) Place the test tube in the water bath using a test tube holder & leave it there for 5
minutes. Ensure the tube is pointing away from you
5) If the food sample contains a reducing sugar, the solution in the test tube will change from
the normal blue colour to green, yellow or brick-red - depends how much sugar is in the food
\Big Molecules - ANS-Starch
Proteins
Fats
,\Biuret Test - testing for proteins - ANS-1) Prepare a sample of your food & transfer 2cm³ of it
to a test tube
2) Add 2cm³ of biuret solution to the sample & mix the contents of the tube by gently shaking
it
3) If the food sample contains protein, the solution will change from blue to pink or purple
\Calculation - Rate of Reaction - ANS-Rate = 1000/time
\Chemical defences of plants - ANS-1) Antibacterial chemicals - these kill bacteria and are
found in mint plants and witch hazels
2) Poisons helped to deter herbivores from eating them e.g. tobacco plants, foxgloves and
deadly nightshade
\Cilia as a defence - ANS-Hair-like structures which waft the mucus up to the back of your
throat where it can be swallowed (and used to trap pathogens)
\Common symptoms of plant diseases - ANS-1) Stunted growth
2) Abnormal growths e.g. lumps
3) Spots on the leaves
4) Malformed stems or leaves
5) Patches of decay (rot)
6) Discolouration
\CONS of vaccinations - ANS-1) Sometimes they don't give you immunity
2) They can sometimes trigger bad reactions e.g. swelling, fevers, seizures - bad reactions
are very rare
\Digitalis - ANS-Used to treat heart conditions
Developed from a chemical found in foxgloves
\Disadvantages of Stem Cells - ANS-1) Stem cells grown in the lab may become
contaminated with a virus - this will be passed onto the patient & make them sicker
2) Some people think that human embryos shouldn't be used for experiments - each one is a
potential human life
3) Scientists should focus more on finding & developing other sources of stem cells
\Drinking as a risk factor - ANS-Drinking too much alcohol causes liver disease, affects brain
function and damages the nerve cells in the brain
\Drug testing - Stage 1 - ANS-Drugs are tested on human cells and tissues
However, human cells and tissue won't determine a drug's effectiveness against an entire
body system
\Drug testing - Stage 2 - ANS-Drugs are tested on live animals - at least two different
mammals
Tests for efficacy (whether it works), toxicity (how harmful it is) and to determine the right
dosage
\Drug testing - Stage 3 - ANS-Drugs are tested on human volunteers
1) Drug is tested on healthy volunteers at a low dosage - reveals any harmful side effects
2) Drug is tested on the sick people it is designed to treat - used to find the optimum dosage
3) The patients are randomly sorted into 2 groups - one group gets a placebo, the other gets
the actual drug
\Epidermal tissue - ANS-Covers the whole plant
\Example of an organ system - ANS-Digestive system - glands (pancreas and salivary
glands), stomach, liver, small intestine and large intestine
\Examples of active transport - ANS-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.
\Examples of tissues - ANS-Muscular tissue - contracts to move whatever it's attached to
Glandular tissue - makes and secretes chemicals like enzymes and hormones
Epithelial tissue - covers some parts of the human body e.g. the inside of the gut
\Explain how the leaves are adapted to maximise the amount of carbon dioxide that gets into
their cells - ANS-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
\Exposure to radiation as a risk factor - ANS-Cancer can be caused by exposure to ionising
radiation, a carcinogen (something that causes cancer)
\Financial Cost of Disease - ANS-1) Cost to the NHS of researching & treating these
diseases is huge
2) Families may have to move or adapt their home to help a family member with a disease
3) If a family member has to give up work or dies, the family's income will be reduced
4) Reduction in the number of people able to work can also affect a country's economy
\Fungi - ANS-Some fungi are single-celled
Other fungi have a body which is made up of hyphae - these grow & penetrate human skin &
the surface of plants
Hyphae can produce spores - can spread to other plants & animals
\Give two ways that the villi in the small intestine are adapted for absorbing digested food -
ANS-1) A single layer of surface cells
2) A very good blood supply to assist quick absorption
\Gonorrhoea - ANS-Bacterial disease
Sexually transmitted disease (STD) caused by sexual contact e.g. unprotected sex
Symptoms: pain when urinating; thick yellow/green discharge from the vagina/penis
Originally treated with penicillin - now some strains have become resistant to it
Treatment with antibiotics and using barrier methods of contraception (e.g. condoms) help
prevent the spread of it
\Greenhouses - carbon dioxide concentration - ANS-Paraffin heaters help increase the
concentration of carbon dioxide - as the paraffin burns, it creates carbon dioxide as a
by-product
\Greenhouses - light intensity - ANS-Artificial light is used after the sun goes down - gives
the plant more quality photosynthesis time
\Greenhouses - temperature - ANS-Help to trap the sun's heat and ensure the temperature
doesn't become a limiting factor
Heaters are used in winter to maintain a high temperature
Ventilation is used in summer to prevent the temperature increasing too much
\Guard cells - ANS-Control the opening and closing of the stomata
They don't open up at night as there is no sunlight
\Hairs and mucus as a defence - ANS-In your nose, they trap particles that contain
pathogens
