B1 aqa revision

  • Created by: 12cpar01
  • Created on: 16-11-16 12:52

energy needs

need energy to fuel chemical reactions this is calledyour metabolism or your metabolic rate.

muscle needs more energy than fatty tissue

bigger people have a higher metabolism

exersize can boost your metabolism

men have a higher metabolism to women

1 of 45

balanced diet

carboydrates = slow release of energy

fats keep you warm

proteins= growth, cell repair and replacement

fibre keeps things moving

vitamins and minerals keep you healthy

2 of 45

unbalanced diet

an unbalanced diet is called malnourishment (you can be fat or thin)

Excess carboydrates and fats can lead to obesity
Common in more developed countries (20% above recommended body mass)
Hormonal problems can lead to obesity through a bad diet, overeating and lack of exersize.

  • people can also experience health problems such as arthritis, type 2 diabetes, high blood pressure, heart disease and some cancers.

Too much saturated fat=higher blood cholesterol
Too much salt=high blood pressure and heart problems

People in developing countries suffer from malnutrition
This can lead to slow growth, fatigue, poor immune systems and irregular periods in women.
-dificiency diseases are caused by a lack of vitamins and minerals e.g. Lack of vitamin c leads to scurvy (problems with skin and joints)

3 of 45


People who exersize regularly are more Heathly than those who don't.

Increases amount of energy used and decreases the amount stored as fat.

Builds up muscle to increase metabolic rate

You can be fit but not healthy ( unbalanced diet)

4 of 45

Inherited factors

Some people inherit factors that can cause an under active thyroid gland which lowers metabolism and leads to obesity.

Some people develop factors that change their metabolic rate ( cholesterol is a fatty substance that in the right balance is good but too much can lead to heart disease.

5 of 45

Slimming products

Take the form of pills, milkshakes and programmes such as the Atkins diet but all claim that you will lose weight.

Key things to look for:

  • is it a scientific study published in a respectable journal?
  • it is written by an independent person?
  • was it a large enough sample size to give reliable results?
  • have other studies found the same conclusions?

Slimming products only work of you:::: eat less fats and carboydrates and do more exersize or burn off energy

Low fat foods only work if you change the rest of your diet as well otherwise you still have a lot of energy

6 of 45

Fighting disease

Micro-organisms that enter the body and cause disease are called pathogens and cause infectious diseases

Bacteria are small living cells that can reproduce rapidly inside your body
They make you feel ill by damaging your cells and producing toxins

Viruses AREN'T CELLS - they are very small
-they invade your cells to create replicas of themselves - the cells then burst releasing the new viruses

  • the cell damage makes you ill.
7 of 45

The body's defence system

Your skin, hairs and mucus stop micro-organisms invading

  • if you cut yourself, PLATELETS help your blood to clot
  • if something does make it through, the immune system kicks in - white blood cells are the most important and are constantly on patrol.


8 of 45


  • if you are infected by a new microorganism, it can take the white blood cells a while to learn *********** it and you can become very ill
    vaccinations involve injecting small amounts of dead or inactive microorganisms (these carry antigens which cause your body to produce antibodies even though its harmless)
  • the memory cells then rememember this for if it really attacks
  • the MMR vaccine vaccinated against Measles, Mumps and Rubella in one vaccine
  • some vaccinations water off over time so sometimes boosters are needed .
9 of 45

Pros and cons of vaccination


  • vaccines help to control many diseases that used to be really common (small pox no longer occurs in the UK and polio cases are extremely rare.
  • epidemics can be prevented if a large percentage of the population is vaccinated.
  • those who aren't vaccinated are less likely to get it than if no one was vaccinated.


  • they don't always work
  • some people have a bad reaction to them but this is very rare.
10 of 45

Fighting disease - drugs

  • some drugs relieve symptoms and other's cure the problem (asprin)
    painkillers do not tackle the cause of the disease instead they just reduce the symptoms.
    other drugs just reduce the symptoms and do not "cure" you.
    antibiotics (penicillin) kill the bad bacteria without killing your body cells
  • certain antibiotics treat certain bacteria
  • bacteria can mutate can become resistant to antibiotics
  • the individual bacteria will survive and reproduce and create a resistance strain of that bacteria
  • MRSA has become resistant to all antibiotics and can kill you

-to avoid this doctors must not over prescribe drugs and the patients must finish the course set.

11 of 45

Investigating antibiotics in the lab

  • microorganisms can be grown in agar jelly with all the correct nutrients they need to grow
  • inoculating loops are then used to transfer microorganisms to the jelly to multiply
  • everything must be sterilised before use to prevent bacteria that isn't wanted entering
  • the dish must have a lid to stop any microorganisms from the air contaminating the results - the lid should also be taped on
  • they are kept at about 25 degrees to prevent them growing too quickly but in the industry this is much higher so its quicker.
12 of 45


He worked in 1840 and noticed that many women were dying from puerperal fever after childbirth.

Blamed the doctors unwashed hands and so made doctors wash their hands in a chloride solution and death rates dropped from 12% to 2%

He couldn't prove this as Pastures germ theory hadn't been proven yet and when he left the hospital they abandoned the idea and the death rate increased again

Basic hygiene is now essential in modern hospitals.

13 of 45

Antibiotic resistance

  • antibiotic resistance is becoming more common
  • bacteria resistance happens when antibiotics are overused
  • because they become resistant they cannot be treated and the disease can pass on quickly
  • "superbugs" are becoming more common
14 of 45

Mutations in pathogens

  • new strains of bacterica can become resistant so treatments can no longer clear up the infections
  • there are always new illnesses that we haven't come across before and so we cannot treat them.
    -new strains of bacteria can spread quickly and there could even be an epidemic.
  • viruses can also mutate often as well but vaccines are hard to develop as the DNA has changed
  • viruses spread very quickly and vaccines take a long time to develop and reproduce
  • a flu pandemic could kill billions of people
15 of 45

The nervous system - sense organs

-A STIMULUS is a change in your environment which you need to react to.

  • 5 sense organs EYES, EARS, NOSE, TOUGUE AND SKIN.
    all contain different receptors (CElls that are sensitive and stimulus)
  • they Change stimulus energy into electrical impulses.
  • the eye is a sense organ and contains light receptors
16 of 45

The central nervous system

  • where all the information from the sense organs is sent and where reflexes and actions are coordinated.
    -it consists of the BRAIN and SPINAL CHORD.
  • Neurones transmit the information ( as electrical impulses) very quickly to and from the CNS
  • "instructions" from the CNS are sent the the effectors which respond accordingly
  • Nerve cells that carry single electrical impulses from the receptors in the sense organs to the CNS.
    nerve cells that carry signals from sensory neurones to motor neurones.
  • the nerve cells that carry signals from the CNS to the effector muscles or glands
    muscles and glands respond in different ways
    muscles contract
  • glands secrete hormones
17 of 45

Synapses and reflexes

Synapses are the connection between neurones
Nerve signals transfused by chemicals that diffuse across the gap
These chemicals then set off a new electrical signal into the next neurones

Reflexes help prevent injury

  • automatic responses to certain stimuli
  • shine bright light = pupils contracts so it doesn't get damaged
  • adrenaline is released so you react more quickly when you're scared
18 of 45

Reflex arc

1. The neurone in reflex arcs go through the spinal chord
2. When a stimulus is dented by receptors, impulses are sent along a sensory neurone to the CNS
3. When the impulses reach a synapse between the sensory neurone and the relay neurone the chemicals released carry the impulses along the relay neurone.
4. When the impulses reach a synapse the same thing happens and its carried through the motor neurone
5. They travel through the motor neurone to the effector
6. The muscle contracts and moves you away from danger.
7. Quicker than a normal response.

19 of 45


They are chemical messages sent in the blood that activate target cells

Carried in blood plasma (control things that need constant adjustment)

Hormones are made by the pituitary gland and the ovaries (women only)

They have long lasting effects

Pituitary gland

-produces FHS and LH involved in the menstrual cycle


  • produce oestrogen for the menstral cycle
20 of 45

Nerves and hormones


  • very fast
  • short
    precise area
    pain signals


  • slower
    long time
    act in a general way
  • feel a bit wobbly afterwards
21 of 45

The menstral cycle

Stage 1 bleeding starts - the uterus lining breaks down for about 4 days
Stage 2 - the uterus builds back up again 4-14 days
Stage 3 - an egg is released from the ovaries
Stage 4- the wall is maintained for about 28 days and if nothing is fertilised the cycle starts again

Hormones control the different stages

  • pituitary gland (causes eggs to mature in overaries)
    produced in ovaries causes pituitary to produce LH
  • produced in the pituitary gland
  • stimulates the release of an egg in the middle of the menstral cycle
22 of 45

Controlling fertility

Hormones can be used
-oestrogen is used to prevent the release of an egg
-progesterone can also be used to limit fertility
-the pill contains both of these (created in 1950's)
Pro's of the pill
-99% effective and reduses risk of getting some cancers
Con's of the pill
-isn't 100% EFFECTIVE
-doesn't protect against STDs
-can have side effects

Increase fertility

  • FSH helps eggs mature
    Pros = helps women get pregnant
    Cons= doesn't always work/get multiple pregnancies
23 of 45


  • take eggs from woman's ovaries and fertilised in the lab with man's sperm
    once they become fertilised embryo's 2 are put into the woman's utters
    given FSH and LH to stimulate egg production

-gave give an infertile couple a child
-strong side effects

  • increased risk of cancer
  • multiple births can happen
24 of 45

Plant hormones

An Auxin is a plant growth hormone and grows at tips, shoots and roots

  • it controls the growth of a plant in response to light (phototropism) gravity and moisture
  • if the tip of the shot is removed the plant may stop growing
    more auxins on the shaded side so it grows towards the light
  • more auxins on the lower side so shoots grow up
  • more auxins on lower sides so it grows downwards
  • more auxins with a side with more moisture so it grows towards the moisture

Plants hormones have uses in Agriculture

  • extractedand used by people
  • plant cuttings wont always grow in soil - you need rooting powders to give the cutting plant hormones
25 of 45


Body levels that need to be kept constant, these are your ION CONTENT, WATER CONTENT, SUGAR CONTENT, AND TEMPERATURE.
-Ion content is regulated by the kidneys==lost in sweat and urine
-Water is lost from the body through skin as sweat, via the lungs in breath and kidneys as urine

  • body temperature is controlled by the brain and enzymes work best at 37 degrees Celsius (brain is a personal thermostat)
  • blood sugar levels need to be controlled too through metabolism and insulin
26 of 45


-drugs change your nobody chemistry

  • you can become addicted and suffer withdrawal symptoms
  • medicinal drugs are medically used (paracetamol is openly available yet morphine has be prescribed)
  • recreational drugs are used for fun. These can be legal or illegal.
  • performance-enhancing drugs can improves a person's performance in sport.

Performance enhancing drugs have health and ethical impacts

  • make athletes better at sport
  • stimulants increase heart rate but steroids increase muscle size
  • negative health effects such as high blood pressure
  • some banned by law or sporting bodies
    Ethical problems
    Against:::unfair advantage/ not aware of side effects
    For::::: athletes own decision/ sport isn't fair anyway.
27 of 45

Claims about drugs

-prescribed drugs lower the risk of heart disease

  • there is evidence to prove it
  • research done by government scientists with no connections to the manufacturers
    compared two groups of patients and other studies backed this up.

-illegal drug

  • scientists say the smoke can cause mental health problems (vary on interpretation)
28 of 45

Testing Medicinal drugs

1. Tested on human cells in lab
2. Tested on live animals (tests for toxicity and dosage)

  • must be tested on two mammals (some people believe this is wrong but others see it as the saftest way for humans)
    3. If the results are good the drugs are tested on healthy volunteers and if this is ok its tested on those who are ill
    4. Patients put into two groups, one is given the drug and the other get a placebo
    blind trials Doctors know patients don't
  • double blind trial - no one knows so doctors cant be biased
  • open - everyone knows

THALIDOMIDE (1950s - went wrong)

  • intended as sleeping pill but better to treat morning sickness
  • hadnt been tested and led to abnormal limb development in foetus'.
    10,000 babies were effected and only half survived
  • the drug was banned
  • now used yo treat leprosy and some cancers
29 of 45

Recreational drugs

-can be legal or illegal

  • illegal drugs can be soft or hard (hard are very addictive and harmful)

soft= cannabis hard=heroin but all cause heart problems

******People use recreational drugs for enjoyment, relaxation and stress relief but also people's history and personal life can lead them to drugs *******

Some studies link cannabis and hard drug use

  • cannabis is a stepping stone to harder drugs
  • cannabis is a gateway drug and brings people into contact onto other drugs
  • genetics can make people more likely to take drugs generally
30 of 45

Smoking and drinking

---------------Smoking is not illegal but can cause heart and lung diseases and the smoke can cause cancer — #---------------Smoking is not illegal but can cause heart and lung diseases and the smoke can cause cancer

-nicotine is very addictive and its hard to stops

---------------Alcohol affects the nervous system and slows down the body's reactions and loss of consciousness and impaired judgment and can cause liver disease and brain damage and it's very addictive — #---------------Alcohol affects the nervous system and slows down the body's reactions and loss of consciousness and impaired judgment and can cause liver disease and brain damage and it's very addictive

These have a bigger impact in the UK than illegal drugs

  • costs the NHs millions
  • lots of money spent for crime
  • economic issues to the users
31 of 45


Desert animals have adapted to save water and keep cool
Camouflage -sandy colour helps them avoid predators or sneak up on prey
Thin layers of body problems and a thin coat to help them loose body heat
Small amounts of concentrated urine

Artic animals
Well insulated
White fur to avoid predators on sneak up on prey
Thick layer of blubber

Desert plants
Small surface area
Stores water in thick stem
Shallow roots to absorb water quickly

Deterring predators
Roses have thorns
Tortoises shells

32 of 45

Competition and environmental change

Organisms compete for resources to survive

  • plants fight over light, space, food and water
  • animals need territory, mates, food and water
    Red and grey squirrels fight each other

Environmental changes caused by different factors
Living factors--- infectious diseases, predators, prey and competitors
Non-living factors---temperature, rainfall, pollution

Environmental changes affect populations in different ways
Population size increases as prey increases as there is more food
Population size decreases due to pesticides, less food and more diseases
Population distribution changes due to ten premature change effecting migration

33 of 45

Measuring environmental change

Living indicators
-organisms are sensitive to changes
-air pollution is measured by levels of sulphur dioxide in the air
-invertebrate species have adapted to water polluted areas

Non living indicators

  • satellites measure the temperature and the amount of snow
    automatic weather stations tells us the atmospheric temperature
    measure rainfall
34 of 45

Pyramids of biomass

100 dandelions feed 10 rabbits which feed 1 fox

Helps explain the food chain

35 of 45

Energy transfer and decay

1. Sun is source for all life
2. Green plants and Algae use this for photosynthesis to make food
3. Respitration supplies most the energy for life processes and energy lost as heat
4. Energy is lost through waste
5. So much energy is lost at each stage

Elements are cycled back to the start of the food chain by decay
1. Planst take in elements and pass them down the food chain
2. They are decomposed
3. Recycled back into the food chain

36 of 45

The carbon cycle

Everything is powered by photosynthesis (co2 removed by plants and turned into oxygen)

Some carbon is returned when plants respireor eaten and it mlkves through the food chain

Some co2 returned when animals respire (microorganisms eat the decaying animals and respire

Animals produce waste that goes back into the food chain

Combustion release co2 back into the air

Constant cycle

37 of 45


Species have different characteristics = genetic variations dn environmental variation

  • caused by different genes passed on through gametes (mixing gene pools)
  • eye colour an blood group inherited
  • evreryone is different accept identical twins who are clones

Environmental variation occurs when there is a difference caused by the the condidtions something has been in

Most characteristics are a mixture of both

38 of 45

Genes chromosomes and DNA

NUCLEUS - contains genetic material in the form of chromosomes

  • human cell nucleus contains 23 pairs of chromosomes
    CHROMOSOMES - carry genes that control characteristics


DNA = coiled up to form the arms of the chromosome

ALLES = different versions of the same gene

39 of 45


-sexual reproduction creates genetically different cells

  • fusion of male and female gametes = mixture of genes
    23 chromosomes from each parent join.

Asexual reproduction

  • one parent with no fusion
    Clones are produces
    create replacement cells
    bacteria and plants
40 of 45


-sexual reproduction creates genetically different cells

  • fusion of male and female gametes = mixture of genes
    23 chromosomes from each parent join.

Asexual reproduction

  • one parent with no fusion
    Clones are produces
    create replacement cells
    bacteria and plants
41 of 45


-cuttings create genetically identical copies

  • cheap and easy

-tissue culture

  • grown all year
  • grown with hormones
    quick with little space

Animal clones use embryo transplants from the best animals to create lots of versions of the best cows

Adult cell cloning involves taking an unfertilised egg cell, removing its genetic material and giving it an elctric shock sp it divides

  • implanted into adult female
  • dolly the sheep was created this way.

Issues with cloning = reduced gene pool/ might not be as healthy/ could be born disables/ we don't know enough about it yet

42 of 45

Genetic engineering

Uses enzymes to cut ans paste genes
-used to create insulin

GM crops have been modified to make them resistant to viruses and pesticides
-genetic disorders like CF is caused by a faulty gene (treated by inserting 'heathly genes called gene therapy)

-could lead to unplanned problems for future generations

Pros ------increase yeils so more food/ no problems yet

Cons------don't know if its safe/ could lead to more bacterial resistance

43 of 45


Everything evolved from a simple life form

  • everything is related
    Simular characteristics mean simular genes
    common ancestor
    Same environment with simular vharacterists

Natural selection
-Charles Darwin

  • survival of the fittest
  • variations in genes
    mutated genes passed on
  • better mutated genes were passed on
  • more chance to breed
44 of 45

More on evolution

Opposition to darwin

  • religious beliefs - dint like that there might not be a creator
  • couldn't give a good explanation
    not enough evidence for many people

-organism becomes more developed in its lifetime (for example if an animal ran a lot its legs would get longer and this would be passed on)

  • aquired characteristics
  • not widely accepted as darwin is more logical

Different hypothesis from simular observation

  • lamarck rejected as experiments didn't support hypothesis
  • Darwin found evidence and it became a theory
45 of 45




great revision material thanks

Similar Biology resources:

See all Biology resources »See all EVERYTHING resources »