B3 revision units 1 and 2

Complete run through of everything in units 1 and 2 for the biology, edexcel, extended unit

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  • Created on: 12-05-12 10:42
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Unit 1
1. FUNCTIONAL FOODS-foods which contain an added ingredient which promotes good
o Prebiotics contain added sugars called oligosaccharides which is `food' for the good bacteria
in our gut (carbohydrates)
o Probiotics contain the `good' bacteria themselves, replace lost bacteria due to stress, illness
o Good bacteria boosts our bodies defence against bad bacteria and break down toxins in our
gut, they compete with the `bad' bacteria for food etc. and when there are lots of them they
eventually suppress the activities of the bad bacteria
o Probiotics produced from fermentation (when bacteria ferment milk and other foods).
Prebiotics are not produced from fermentations.
o Stanol esters-Benecol-lower cholesterol
2. Making of soy sauce and yogurt
o Remember...Lactobacillus bacteria ferments the sugar lactose into lactic acid which lowers
the PH of the milk and causes it to coagulate
o Soy sauce 1. Aspergillus mould (enzymes produced by it catalyse the breakdown of
carbohydrates and proteins into sugars and amino acids) 2. Brine (sodium chloride solution)
for salty taste and preserve final product 3. Lactobacillus bacteria and yeast added-stop
mould activity and ferment the sugars and amino acids. Filtered and pasteurised (720C ­ this
keeps it fresher for longer and kills any bad bacteria that could cause illness)
3. Cheese
o Rennet (traditionally from the stomach of slaughtered cows) vital to cheese making process,
contains two protein-digesting enzymes which cause milk to form solid curds (whey)
o Mainly consists of chymosin (which can be made from GM bacteria) works same way as calf
rennet except activity is more predictable, it contains fewer impurities and is acceptable to
o Cheese made using GM chymosin rated GM free because it is not made using GM organisms
4. Weird names and uses
o Gelling agents ­thicken food-gelatine is an example, also carrageen extract from seaweed
works as a gelling agent and is acceptable to vegetarians
o Mould fungus Aspergillus Niger used to produce citric acid-added to fizzy drinks, jams etc.
and brings out flavour-also prevents the breakdown of vitamin C in food.
o Bacterium Acetobacter used to produce vitamin C. The process is a fermentation in two
stages starting with glucose
o Bacterium Corynebacterium glutamicum used to produce amino acid glutamic acid.
Neutralisation of acid makes a sodium salt called monosodium glutamate (MSG)

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Yeast fungus Saccharomyces cerevisiae used to produce invertase (also called sucrase). The
enzyme promotes breakdown of sugar sucrose into glucose and fructose. Invertase is used
to convert solid insides of chocolate into a liquid centre.
o Glucose isomerase-enzyme used in sweet making-converts glucose into fructose (it is very
sweet) used to make sweets
5. GM crops *Genetic engineering ­technology that involves moving genes (DNA) from
one organism to another.…read more

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This reduction reduces risk to wild life
and lessens damage to the environment
Increased yields-food-money
6. Genetically engineered insulin *Vector-an organism used to transfer genes from one
organism to another *Fermentation-when micro-organisms break down large
molecules in the absence of oxygen to produce different substances (like food stuffs
and drugs)
o Insulin is cheap and safe to use because chemically it is the same as the insulin our cells
produce naturally. When grown in a fermenter large amounts can be made quickly.…read more

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Salbutamol used to treat people suffering with asthma
o Enzymes in the liver break down drugs-however variations in the genes which code for
the enzymes means that their action in some people is more effective than in others.…read more

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Advantages: Faulty genes eliminated, reduced risk of sex-linked genetic disorders
(haemophilia/ fewer terminations
o Disadvantages: May skew gender balance, risk of designer babies
Biotechnology: The process where we use plant cells, animal cells and micro-organisms to produce
useful substances
Unit 2
1.…read more

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If care increases chance of offspring surviving then parents indirectly benefit because
their genes pass from one generation to the next. Maybe parental care is all about
increasing the survival of parental genes
o Very common among vertebrates such as birds, mammals and some reptiles
4.…read more

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Conditioning- The process where animals learn to associate a desired outcome with a stimulus that
is not directly linked to the possibility of the outcome
Classical conditioning; Animal will learn without trying (rattle a dogs lead before going on a walk,
dog will soon learn to associate the sound of a lead being rattled with going on a walk
Operant conditioning: Animal learns to do something by being rewarded (or punished).…read more

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Anthropomorphism: The way we describe animals, plants and objects as having human
characteristics. We explain animal behaviour in terms of human emotions and characteristics.
(Anthromorphic) Giving animals human characteristics, dressing animals in clothes
Self-awareness: The idea that we know we exist. Self-awareness allows us to have an idea of what
other people may be thinking. We might recognise another person's mental state and use our
understanding to influence their behaviour to our advantage.…read more

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