Biology b3

B3 revision

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  • Created by: bambi
  • Created on: 13-05-12 14:58

Yogurt production

1 milk is pasteurised to kill any pathogens and cooled to 45 degrees

2 a culture of lactobacillus burglarious is added to warm milk this is done in the fermenter.

3 the bacteria break down the lactose sugar in the milk into lactic acid.

4 the lactic acid lowers the ph of the mixture

5 the milk protein ,casein , coagulates the mixture causing it to thicken and set

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Yogurt production

1 milk is pasteurised to kill any pathogens and cooled to 45 degrees

2 a culture of lactobacillus burglarious is added to warm milk this is done in the fermenter.

3 the bacteria break down the lactose sugar in the milk into lactic acid.

4 the lactic acid lowers the ph of the mixture

5 the milk protein ,casein , coagulates the mixture causing it to thicken and set.

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cheese making

1 a starter culture of bacteria is added to warm milk . An enzyme called rennin is also added to make the milk curdle faster

2 Curds are formed that are more solid than those of yogurt

3 The curds are separated from the remaining liquid parts of the milk this is known as whey.

4 Bacteria and moulds are added to the curds to slowly (ripen) mature the cheese.

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Other uses of micro organisms

Acetobacter- used in the production of vitamin c

Saccharomyces ceravisae which is a type of yeast - produces the enzyme invertase which converts sucrose into glucose and fructose ( a very sweet sugar found in fruits and honey) to produce the semi liquid centre in some chocolate eggs.

Aspergillus Niger - used to produce citric acid which is used as a flavour enhancer and as a preservative in fizzy drinks

Corynebacterium glutamicum - used to produce glutamicum acid which is turned into msg (a flavour enhancer)

Mucor miehei- this fungus produces the enzyme chymosin which is used as an alternative to rennet(from calves stomach) to help milk curdle and office vegetarian cheeses

Bacillus theringiensis- produces a toxin that kills insects , used as a biological control agent, the gene can be put into cotton plants to produce a natural pest resistance.

Plant stanol esters -are chemicals and are used to reduce cholesterol by 10 % produced commercially by using bacteria to convert sterols ( types of fat found in plants such as soya bean) into stanols

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Soy sauce

1 Soy beans are soaked and the pressure cooked

2 The resulting mash is mixed with flour and a culture of the fungus aspergillus oryzae is added

3 The aspergillus oryzae secretes enzymes which break down the starch molecules to smaller sugar molecules

4 The mixture is heavily salted and lactobacillus bulgaricus and yeast is added, this stops the the aspergillus secreting hormones and stops it growing.

5 The mixture is left to ferment for several months (6 months) producing a red brown mixture

6 The mixture is filtered , pasteurised and bottled for consumtion.

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Producing herbicide resistant crops

1 Get a plant that is resistant to the herbicide and select the gene needed

2 cut out the herbicide resistant ( hr )gene from the plant cell using a restriction enzyme.

3 Angro bacterium tumerfacians bacteria contain a loop of DNA called a plasmid remove it from the bacteria and cut it open using a restriction enzyme

4 Insert the hr gene onto the sticky ends of the bacterium plasmid using ligase enzymes and insert into the bacterium

5 Allow the agrobacterium to infect the cells of the target plant

6 the bacterium cause a crown gall to grow on the plant . The genetic material of the gall cells will contain the hr gene

7 Grow a tissue culture of the gall cells in s medium including the herbicide , those that grow must contain the desired gene.

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Production of insulin

Insulin is a hormone released by the pancreas which helps to control sugar levels in the blood. People with diabetes can't produce this hormone.

1 gene for human insulin is identified

2 Gene inserted into plasmid

3 plasmid inserted into bacterium escherichia Coli . This bacterium now starts producing insulin

4 the bacteria grows in fermenters at body temperature.

5 bacteria are killed by heat sterilisation and the insulin is extracted and purified.

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More uses of plants

Carrageenan - a type of seaweed

Used as a gelling agent

It is also used as an emulsifier in ice cream , jellies and soups

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Drugs from plants

Willow bark - used to make aspirin which is used to lower fever and as a pain killer

South American cinchona tree - used to make quinine which is an anti malaria drug

Pacific yew tree - used to make taxol which is an anti cancer drug . It is a protected tree and slow growing which means scientists have to use other methods to extract it.

Artemesia annua- used to make artemisinin which is used to treat malaria and skin diseases

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Advantages and disadvantages of gm crops


1 increases crop yield by providing resistance to pests and herbicides

2 allows crops to be grown in areas that are too hot or cold

3 increases shelf life of some products such as the flavr savour tomato.

4 crops can be produced that provide vaccines or other medical benefits


1 could cause unintended harm to other organisms eg butterflies can be harmed by gm pollen.

2 more herbicide will be used as there are more crops

3 possible gene transfer to other plant species

4. People are worried that theory will be allergic to gm food.

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A bmi equal or greater than 30 is classed as obese

Being over weight carries these risks

1 heart disease due to increased cholesterol causing fatty deposits to build up on arteries and this may lead to a possible heart attack

2 diabetes ( type 2) due to there not being enough insulin produced to convert the sugar into fat.

3 certain types of cancer such as breast or colon

4 osteoarthritis which affects the joints and causes restricted movement.

5 there is also an increased risk of high blood pressure

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Unbalanced diet

Protein deficiency can cause a condition called KWASHIORKOR . This is not common in developed countries but is a problem in developing countries

Vitamin deficiencies can cause problems such as scurvy which is a lack of vitamin c

Mineral deficiencies can also cause problems such as iron which leads to anaemia. This is when red blood cells can't get enough oxygen to the rest of the body.

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Carbohydrates - provide energy

Fats - provide energy provide insulation , act as an energy source , provide insulation , and form cell membranes and steroid hormones.

Protein- they are needed for growth and repair of tissue, and provides energy in emergencies.

Vitamins - are needed to perform functions in the body

Minerals- used for various functions such as iron needed to make haemoglobin in the blood

Water - used for transfer in the body

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Stem cells And biotechnology ethics

Stem cells are undifferentiated cells with no hay flick limit ( divides no more than 52 times ) that can differentiate into any other cell .

They can be used to cure a variety of problems such as altzhiemers muscle damage or Parkinson's Disease

Adult stem cells can only differentiate into a small number of cells so embryonic stem cells are needed

This is deemed unethical ad the embryos have the potential to be a child.

Biological ethics

1 it may mean that gender of babies can be chosen this could lead to a gender unbalance in countries such as china where boys are more important than girls. It means that genetic diseases can be avoided.

2 it could allow clones to be made for organ transplants which Is unethical as the clone would have a right to live

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Instinctive and learned behaviour

Instinctive behaviour

Taxism- movement of an organism in response to a stimulus

Kinesis- movement and change in speed of an organism in a response to a stimulus .

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First described by Konrad Lorenz,

Imprinting occurs at a particular time (termed the sensitive period) during early postnatal

life. For example, in anserine birds such as ducks and geese, the time for imprinting is

24-48 hours after hatching when the 'following response' is learnt.

Although the dominant sense involved in imprinting is sight, sound and olfaction are

also involved.

In a variety of experiments, young chicks and ducklings were imprinted on humans,

wooden blocks and classically even old gum boots. They bonded with a single item and

would follow it wherever it went.The imprinted knowledge is retained for life. Of all forms

of learning, imprinting is the least likely to be forgotten or unlearn once they have imprinted, animals will always prefer to follow the learned stimulus rather than a member of their own species. The following response in ducks that have imprinted on humans means that the ducks will preferentially follow any human rather any duck.

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If you keep on giving an animal a stimulous that does not benefit it it learns not to respond to it . Such as when scarecrows stop reacting to scarecrows.

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Types of conditioning

Operant learning - It is a trial and error way of learning where an animal learns to associate an action with a reward.

Classical conditioning - has two parts 1st is an inate response to a stimulus - such as saliva when presented with food.

2nd Is a completely unrelated stimulus that occurs at the same time as the initial stimulus over repeated exposures . The animal accociates the two stimuli to bring about the first stimuli when presented with the second eg dog salvates when a bell rings.

Over time the animal forgets this act and it was discovered by ivan pavlo in Russia.

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Types of animal communication

Bee waggle dance- the bee waggles in a figure of 8 movement . The bee waggles to inform the other bees where food is . The vigorsity of the dance informs the other bees about how much food there is . It waggles in the direction of food.

Courtship behaviour

It is more complex in animals where both parents are needed to care for the young.

It is needed to

1 to check the partner is the right species

2 to choose the best mate possible

Ritual dances/ display reinforce the bonding between the is the female choice

Special visual structures and colours used ( such as peacock feathers) as well as sounds such as bird songs.

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Types of communication

Smell- animals can mark territory which means that they can Mark territory and ward off any potential threats

Visual - can be used for courtship such as displays for attention

Sounds- used as warning signals or mating calls

Chemical - pheromones released to influence the behaviour of others eg can make someone appear more attractive

Territorial and aggressive communication

A territory is selected and defended by individuals of the same species

This is done by aggression and scent marking as well as sounds such as birdsong.

The advantage of this is that the population becomes spread out in relation to food supply and there is less competition for food.

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Alarm signals

Animals such as birds use this to warn each other of predators. The individual giving the alarm signal reduces it's chance of survival. The animal does this because it's young are likely to benefit.

The alarm call of many species is similar such as in birds so individuals respond to alarm calls given by different species.

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Parental care

Parental care- One of the parents staying in order to keep young together and fend off predators . This os done in order to increase the likelihood that the child will survive until adulthood . This means that it's genes will be passed on.

The more care that is needed the less offspring that is produced this is in order to make them live until adulthood . If many young is produced there is a very small chance that even one makes it to adulthood.

In herbivores the offspring have to be able to run quickly leading to shorter parental care, the young learns how to do stuff fast as due to migration they are always on the move..

In carnivores the offspring is often helpless and have long childhoods as they are protected within their territories . They are brought up and taught how to hunt.

Where adults show more complex behaviours the offspring need more parental care and teaching.

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Examples of parental care

Giving food- showing offspring how to eat and how to get it

Hunting - teaching animals how to catch food

Providing milk- suckling young

Grooming -keeping youngsters clean and teaching to eying behaviours

Danger- what not to eat

How to avoid predators

Makes habitat for youngster and protects them


Less food for parent

If parent dies child dies

Parents put themselves at risk to get food

conflict to get rid of mature offspring

Offspring wants more that the parent willing to give

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Herbivore adaptions

1 large lower jaw for a large chewing master mucle

2 teeth that never stop growing they grind from left to right in order to grind food into a paste

3 diastema - in order to get a big mouthful of food so they can look for predators while eating their food

4 eyes mounted at side of skull to give a very wide field of vision . This makes it difficult for a predator to sneak up on them

5 herding behaviour - living in big groups

6 digestive system- big stomach to hold lots of food bacteria digest the plant cellulose

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Herding behaviours


1 harder to be singled out

2 less probability of being caught

3 don't have to be as fast as predators , just not the slowest one.

4 predators spotted earlier as more animals are watching

5 shielding young

6 easier to search for food


More food for a predator

More competition for food.

Spread of diseases and parasites

More mating rivalry

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Carnivore adaption

1 eyes at front

2 smaller jaw to give more powerful bite

3 large teeth that are sharp and don't grow back.

4 smaller teeth to pick through flesh

5 sharp molars to cut animals into chunks

6 jaws can't move sideways


Sneaky - hide in cover

Pack hunter - communication essential

Pick at weakest prey

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