Biology, B3, Edexcel

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Production of Soy Sauce

The three important microbes in this process are:

  • Aspergillus fungus
  • Yeast
  • Lactobacillus bacterium

1. Cooked Soy beans and Roasted Wheat are mixed together

2. The mixture is fermented by the Aspergillus fungus

3. The mixture is fermented by yeast

4. The mixture is fermented by Lactobacillus bacterium

5. Mixture is filtered.

6. Liquid is pasteurised and put into sterilised bottles.

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Fermentation of Milk to produce Yoghurt

Fermentation is when micro-organisms break sugars down to release energy - usually by anaerobic respiration. 

1. Equipment is sterilised

2. Milk is pasteurised then cooled

3. Starter culture of bacteria is added and mixture is incubated in fermenter 

4. Bacteria ferment the lactose sugar to form lactic acid. Lactic acid causes milk to clot solidifying to form yoghurt

5. Flavours are added

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Functional Foods

  • Plant stanol esters - lower blood cholesterol, reduce risk of heart disease, often included in spread and dairy products, occur naturally in small quantities.
  • Prebiotics - promote growth of good bacteria, food supply for good bacteria, occur naturally.
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Microbial Products

  • Enzymes - used in the manufacture of sweets and other foods.

          Example: invertase converts the sugar into glucose and fructose for a                     sweeter taste, making the product need less sugar overall.

  • Chymosin - made from rennet from lining of a calf's stomach.

          Example: cheese is made from chymosin, vegetarian cheese is made from               chymosin from gm micro-organisms.

  • Vitamin C - used as a dietary supplement, also added to drinks to stop them going off. 

          Acetobacter naturally produces a chemical easily converted to vitamin C, to             make it easy to produce commercially.

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Microbial Products

  • Citric Acid - flavouring and preservatice added to fruit-flavoured fizzy drinks, found naturally in citrus fruits.

          Aspergillus niger is used to commercially produce citric acid.

  • Monosodium Glutamate (MSG) - flavour enhancer added to ltos of foods, made form glutamic acid.

          The bacteria secrete glutamic acid which is then used to make MSG.

  • Carrageenan - a gelling agent extracted from the seaweed carageen.

          Example: emulsifier in ice cream, jellies and soups.


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Balanced Diets

Six essential nutrients:

  • Carbohydrates - provide energy
  • Fats - provide energy and insulation
  • Proteins - used for growth and repair of tissue
  • Vitamins - maintain healthy tissue 
  • Minerals - iron is used to make haemoglobin for healthy blood
  • Water - constant suplly due to loss during urinating, sweating and breathing
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Unbalanced Diet

If you do not get enough of specific nutrients you may suffer from side-effects such as:

  • Minieral deficiencies - anaemia (blood disorder)
  • Vitamin deficiencies - scurvy from lack of vitamin C

Too much carbohydrates, fat or proteins can lead to obesity which lead to risks of diabetes, arthritis, high blood pressure and even some forms of cancer.

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Genetically Modifying Plants Uses

  • To make herbicide-resistant plants - to remove weeds so no competition
  • To make disease/pest resistant plants
  • To increase nutritional value /shelf life / flavour/ texture of plants.
  • To modify crops so they can grow in a hostile environment
  • To modify so they contain medical benefits/vaccines
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Genetically Modifying Plants Process

1. Cell with desired DNA (e.g. herbicide resistance). Desired DNA is cut out using Restriction Enzymes.

2. Plasmid is cut open also using restriction enzymes (Sticky Ends.)

3. The DNA is inserted into the Plasmid. The sticky ends are bonded with DNA Ligase.

4. Add the plasmaid into the bacteria Agrobacterium Tumefaciens (it is able to transfer genetic data). The bacteria can infect the plant.

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Genetically Modifying Plants Uses

Biotechnology/GM Plants could help malnutrition in developing countries by:

  • GM to be resistant to pests
  • GM to grow in hostile environments
  • GM to combat a certain deficiency. e.g. 'Golden Rice' to combat Vitamin A deficiency.

Disadvantages of GM crops:

  • Transplanted genes may be released into the environment ('superweeds').
  • May Reduce biodiversity (affects numbers of weeds, flowers and wildlife).
  • Safe? Worries of allergies (although none have been found).
  • In developing countries the problem is money not availabilty of food.
  • Still cannot be grown if there is poor soil.
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These drugs all come from plants:

  • Aspirin - a pain killer from the bark of a willow tree. The active ingredient is Salicin.
  • Taxol - an Anti-cancer drug from the bark of a Pacific Yew tree. The active ingredient is Paclitaxel.

          Although, the tree is protected as it is slow growing and harvesting taxol kills the               tree so have to find other ways to produce the drug.

  • Quinine- an Malaria Treatment drug from the bark of a Cinchona Tree. The active ingredient is Quinine.
  • Artemisinin- an Anti-malaria drug from the plant Artemesia Annua. The active ingredient is Artemisinin.
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Drug Development

Drug development is very expensive and can cost a lot of money due to the patent on it therefore it is very controversial.


  • Drug companies could charge less and still make a profit.
  • Making a profit from illness is unethical.
  • Drugs should be allowed to be copied and produced more cheaply.


  • The drug companies need to cover the costs of the expensive research that went into making the drug.
  • No reason to develop new treatments if cannot get a profit.
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The study of Genomes and their uses, some of which are:

  • Research could lead to discovery of specific genes which link to a disease and therefore could get an earlier diagnosis or prevention of a disease.
  • Can help understanding of how a specific gene causes a disease. This could result in a new treatment for the disease.
  • Could help to predict how specific genes can link to the person's response to a drug - tailor made drugs = less side effects.
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Reproductive Technology

In vitro fertilisation (IVF) is used to help infertile couples have children.

Need healthy sperm, eggs and uterus - any of them can be donated.

Against IVF:

  • Not natural.
  • Not all eggs from the woman are implanted and throwing them away is unethical (denying life etc...)
  • Increases chances of multiple pregnancies, e.g. twins, could be danger to mother's health or a financial burden.
  • What happens if surrogate mother does not want to give up the child.
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Embryonic Screening

  • Screening is allowed for genetic disorders.
  • Screening is allowed for a 'tissue match'. A baby which would have the same genetics so could be used to help give tissue to a sick sibling. Spare part child?
  • Illegal to choose sex of baby unless there is a medical reason (e.g. a genetic disorder affecting one gender in the family).
  • Specific cells can be removed from an embryo before being implanted. Could, in theory, let parents choose characteristics of their baby. Slippery slope to designer babies.
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Stem Cells

Embryonic Stem Cells can differentiate into any sort of cell. Stem Cells are also found in adult's bone marrow but are not as versatile.

Stem Cells could cure many health problems:

  • Blood diseases (e.g. Sickle Cell Anaemia) can be treated by bone marrow transplants. New blood cells to replace the old ones.
  • Embryonic stem cells could be used to regrow faulty cells in sick people (e.g. muscle cells or nerve cells)

Parkinson's Disease - loss of a particular type of neurone in the brain that affects movement. New nerve cells could be grown with stem cells.

Controlling the differentiation of the stem cells is done by changing the environment they are grown in but is very difficult and unreliable.

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Instinctive and Learned Behaviour

Instinctive Behaviour is inherited and the same within species . It is the right way to respond to a stimulus straight away without being shown. Often links to the survival of the animal.

E.g. Earthworms move away from light.

Learned Behaviour - Learnt from the animal's experiences and lets it respond to changing conditions.

E.g. Birds kept in isolation when young do not learn proper bird song.

Habituation = when there is a repeated stimulus, which is neither harmless nor beneficial, the animal quickly learns not to respond to it.

E.g. Crows learn that scarecrows are not harmful and ignore them.

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Classical Conditioning - animal learns passively to associate a 'neutral stimulus' with an important one. Response is automatic and reinforced by repition.

E.g. Pavlov's dogs. Associated the bell ringing with the food and eventually salivated at the sound of the bell instead of the food itself.

Operant Conditioning - animal learns acitvely using trial and error to associate an action with reward and punishment.

E.g. Skinner box. An option of buttons to press one of which to get food. After a while pigeons and rats learnt to only press the one which would bring them food.

We use conditioning to train animals e.g. dogs to sit with reward of food.

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Sound - language. e.g. bird's calls to declare territory, attract a mate or warn others about predators.

Chemical - Pheremones: externally released chemicals which other animals of the same species can pick up and respond to. e.g. to mark territory or alert others if they are under attack.

Physical - facial features or body language. Although, these are species specific e.g. when a money shows it's teeth.

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Feeding Behaviours

Herbivores spend a lot of time eating because plants are low in nutrients such as amino acids whereas carnivores spend a lot less time eating but must make sure their diet contains a lot of protein.

Live/hunt in packs because:

  • More chance of getting larger/more prey.
  • More intimidating.
  • Group defence against predators and defend catch.
  • Dilution - less chance of individual being eaten.
  • Confusion of predators by rapid direction changes.
  • Vigilance - many eyes and ears to see predators and prey.


  • Sharing food - hierarchy
  • Less stealth
  • Chance of being cast out - reproductive reasons.
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Reproductive Behaviours

  • Songs or calls
  • Pheremones
  • Fighting - display strength
  • Courtship displays (songs, dances, brightly coloured etc...)

Female chooses a mate which demonstrates the best survival skills (be fit/healthy) so that her young will inherit the skills and increase their chances of survival.

Some animals look after their young:

  • Protection - one parent stays with them or nests for protection.
  • Feeding
  • Teaching skills - e.g. how hunt. Imitating behaviour.

Looking after young increases their survival but can put the parent in danger. Do it because: less time pregnant which is more risky + they want to ensure the species survives.

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Ethan hicks


cherss robby xoxoxoxox

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