- Milk is heated to 40°C to kill any bacteria or micro organisms. This is called pasteurisation.
- It is then stirred thoroughly and milk protein is added.
- The starter culture Lactobacillus is then added, whilst the milk is still warm. (Needs to be warm so that bacteria grow, reproduce and ferment.)
- The Lactobacillus (because of the enzymes) ferments the sugar Lactose from the milk, and turns it into lactic acid.
- Lactic acid then causes the milk to lower in pH and the milk curdles/solidifies. The curdled milk is now yoghurt.
- It can either be put into a pot and sold as is, or flavours/fruits can be added in order to enhance the flavours.
- It is then packaged and then sold.
Making Soy Sauce
- Cooked soy beans (this kills bacteria etc) and roasted wheat are mixed together
- Aspergillus mould is added to the mixture to ferment it
- Brine is then added to make it taste salty
- Yeast and Lactobacillus are added to ferment the mixture
- The liquid is filtered to remove any residue
- It is then pasteurised to kill microorganisms
- Then is it bottled in sterile bottles.
Prebiotics are not disgestable foods. They stimulate the growth of useful bacteria - (Lactobacillus & Bifidobacterium) in the colon. This means they contribute to a person's general health.
Two examples are: + Plant sterol esters.
Plant Sterol Esters: Found in very small amounts, they are produced commercially by using bacteria to convert plant sterols (a type of fat) into stanols.They can lower cholesterol, reducing the risk of heart disease. They are used in products such as butter so that they can promote them as being healthy.
Oligosaccharides: Naturally in leeks and onions, they are short chain carbohydrates. They stimulate the growth of beneficial bacteria in the large intestine.
Using Microbes to Alter Food
Microbes are used in the food industry to make chemicals that are added to food. This is done in order to: + prolong shelf life
+ improve flavour, texture & appearance
These chemicals are known as microbial products.
Cheese is made when the enzyme chymosin acts on milk.
Chymosin was originally obtained from the stomachs of calves. However, it is now produced from GM microorganisms in very large quantities through genetic engineering.
The gene respinsible for chymosin was isolated and transferred to yeast cells. This yeast is a genetically modified organism.
This means that vegetarians are able to eat cheese that is produced without the use of animal products (except milk).
Balanced Diets and Obesity
A balanced diet includes a range of different foods. It is important to eat a balanced diet so that the body is provided with energy and nutrients to work properly. It is important for teenagers and children, who are still growing.
A balanced diet includes all the basic food groups in the right proportions.The balanced diet you require, depends upon your age, gender & level of activity
Obesity: the condition of being very overweight. You become overweight mainly as a result of eating an unbalanced diet and not doing enough exercise. A person who is obese is likely to develop: arthritis
high blood pressure
World Food Supply and Biotechnology
Developing countries rarely have enough food for the people who live there. Many parts of Africa and Asia experience severe food shortages due to:
- the environment - poor soils and water shortages
- poverty - people too poor to buy foods, or buy land/equipment to grow their own
- wars - wars often prevent food from getting to those who need it
Biotechnology uses organisms to make useful substances, including foods, and chemicals that can help food to grow.
This means that biotechnology could have the potential to alleviate the shortage of food in many parts of the world.
Breeding Herbicide Resistant Crops
Herbicides are used to kill weeds. However the herbicide may also kill some of the crop. Therefore, breeding herbicide resistant crops enables people to produce more crops.
It is done by:
- Scientists find a naturally occuring plant that is herbicide resistant
- Scientists identify the gene that is responsible for the resistance
- A vector, such as Agrobacterium tumefaciens is used to transfer the gene coding for herbicide resistance to the embryo crop plant's genome
- The crop plants are allowed to grow and are then treated with the herbicide
- The new plants are resistant to the herbicide.
Breeding Insenct Resistant Plants
Bacillus thuringiensis produces a toxin that kills many insects. The gene responsible for the toxin can be identified and transferred into the genome of crop plants. This makes the crop plants resistant to insects. It is done by:
- The Bacillus thuringienis bacterium produces a toxin
- Scientists identify the gene that is responsible for producing the toxin
- A vector is used to transfer the gene coding for toxin production to the embryo crop plant's genome
- The crop plants are allowed to grow
- The new plants are resistant to insect pests.
The Ethics of Biotechnology & GM
Biotechnology: Some believe that measures like breeding herbicide resistant crops will make a significant contribution towards alleviating the world's food shortage.
Others feel that the food shortage in many parts of the world is a political/economic problem and that, because biotechnology is relatively new new technology has not yet fully been tested, it should not be relied upon to solve the problem.
Some people think that the world's rich nations should spend some of their money on transporting food to areas/countries that lack food.
Genetic Modification: Many scientists, as well as members of the public, are concerned that the GM organisms could lead to problems such as:
- long term problems with eating GM crops
- will GM organisms spread their genes to other organisms, i.e. pollen from GM crops that are resistant to herbicides could spread to weeds and therefore make them resistant.
Choosing the Sex of a Baby
Scientific advances in genetics have made is possible for parents and doctors to choose the sex of a baby. Some people feel that this is going against nature, however. There is a worry that allowing people to choose the sex will skew the balance of the sexes in the world's population.
Choosing a baby is seen as being part of the 'designer baby' debate. They believe that it could lead to parents also being able to choose their child's features like eye colour and/or their intellectual ability.
Many people believe that letting people choose the sex of their baby and their characteristics is going against 'nature's way' and 'God's will.' As a result, doctors and scientists find it difficult for people to accept such scientific advances.
Stem Cells and Parkinson's Disease
Stem Cells: undifferentiated cells that have the potential to develop into specialised cells (cells that can perform a particular job.)
When different chemicals, growth factors, are added to stem cells, they are made to develop into:
- insulin-producing cells in the pancreas
- heart muscle cells
- blood cells
- bone marrow cells
Parkinson's Disease: When the neurones in the brain stop producing dopamine, a person developes Parkinson's disease. Dopamine is a chemical that the neurones use to communicate to each other. When dopamine is not produced, the brain is unable to coordinate the movements of the body (amongst other things.)
If stem cells could be made into brain neurones that produce dopamine, this could potentially cure Parkinson's disease.
Genomics: the study of an organism's entire genome (its DNA.) (Genome: all the genetic material of an organism.) Biotechnology uses genomics to produce new medicines. One example of biotechnology and genomics used together is in the production of blood clotting factors.
Haemophiliacs' blood cannot clot and so they continue to bleed when they are cut. Blood clotting factors can be produced safely in the milk of sheep that have been GM to code for the human version of the missing protein.
Other examples include:
- to produce human protein, interferon, which prevents viruses from multiplying once inside the body
- to produce human growth hormones which are used to treat abnormal growths
- to produce human insulin, which is used to treat people with diabetes
Genetic Engineering and the Production of Insulin
Human insulin is made by genetic engineering. Prior to this, cow insuling was used, and there were side effects. It was also discovered that BSE could be passed onto humans.
The production of insulin:
- The gene for insulin production is identified. It is removed using a restriction enzyme.
- Another restriction enzyme is used to cut open the a ring of bacterial DNA (a plasmid.) Other enzymes are then used to insert the section of human DNA into the plasmid.
- The plasmid is inserted into a bacterium which starts to divide rapidly and as it divides, it replicates the plasmid. The bacteria are cultivated on a large scale in fermenters and soon there are millions of bacteria, each carrying th instructions to make insulin. When the bacteria then make the insulin, commercial quantities are produced.
Medicines from Plants
Although many medicines are now made synthetically, many still originate from plants. People have known about the importance and medicinal value of drugs from plants for a long time.
- Aspirin - Found in the bark and leaves of willow plants. Used for pain relief. It works by inhibiting the production of certain hormones which transmit 'pain information' to the brain.
- Taxol - Found in the bark of the Pacific yew tree. Treatment of some cancers i.e. breast cancer & ovarian cancer. It works by disrupting mitosis so the tumour cells cannot divide.
- Quinine - Found in the bark of the cinchona tree. Treatment of malaria until the 1930s. It works by preventing the malarial parasite from feeding on the haemaglobin properly.
- Artemisinin - Found in the Chinese plant Artemisia annua. Treatment of malaria and reducing transmission of malaria. It is not fully understood how it works.
Instinctive & Learned Behaviour
How an animal responds to a stimulus is called its behaviour. Some patterns of behaviour are called instincts. Instincts are: inherited from parents & not affected by the environment.
All members of a species inherit instinctive behaviour. For example, suckling by a newborn mammal is an instinct.
Young animals are able to learn from their parents. Some behaviours are not instinctive; they have to be learned through conditioning. Conditioning can be either classical or operant.
Classical & Operant Conditioning
In classical conditioning, an animal will learn without actually trying i.e. if you rattle a dog's lead before a walk, the dog will associate the sound of the lead with going for a walk. Ivan Pavlov, noticed that dogs salviate when they are shown food. He decided to see what would happen if he rang a bell each time the dogs were shown food. Eventually the dogs salviated whenever they heard a bell - even if there was no food.
In operant conditioning, an animal learns to do something by being rewarded or punished. People can condition (train) animals to do particular, like:
- train guide dogs for the blind
- train sheep dogs to round up sheep
- train sniffer dogs to find people/search for drugs.
Habituation & Social Behaviour and Communication
Habituation is believed to be the simplest type of learning. It happens when an animal stops reacting to a stimulus that has no effect on the animal. The animal has learned to ignore it. It is part of the learning process in young animals.
Social Behaviour & Communication: Animals communicate with members of their species (and some other species i.e. to warn them off.) Communication is useful to animals because it enables them to:
- warning each other of danger
- working together when hunting
- attracting a mate (courtship behaviour)
It helps them to survive.
Ways of Communicating & Making Sounds
Animals can communicate in different ways, for example
- by making sounds
- by producing chemicals (usually smells)
- by giving signals or displays
- through body language and facial expressions
Making Sounds: Most animals communicate by making sounds:
- some snakes hiss to signal the presence of a predator
- a big cat will produce a low growling sound to let other cats know that they are not welcome in its territory.
Some animals, like whales, can communicate over very long distances, whereas others, like birds communicate over much smaller distances.
Producing Chemicals & Signals and Displays
Pheromones are chemicals that some animals release into the environment, they are used to attract a mate, scare of competitors or mark out a territory:
- female dogs that have just given birth produce pheromones that provide a feeling of comfort to their young
- female moths release pheromones that attract male moths, male moths use their attennae to detect the sex pheromones.
Signals and displays: Many animals are able to communicate by making a signal or display. These can be used to attract a mate or present a threat etc:
- rabbits and hares thump their hing legs on the ground as a warning signal
- male birds of paradise hang from tree branches and shake their colourful feathers to attract females.
Body Language and Facial Expressions
Most mammals are able to communicate through body language. It is used to communicate: fear, affection, dominance and submission. Many mammals are also able to use facial expressions to communicate with members of their own species. For example, chimps have a range of facial expressions that they use to communicate different emotions to each other.
Body language and facial expressions are species-specific, this means that they are used for communication between indiviuals of the same species, and may be taken to mean something quite different by members of other species. For example, chimps bare their teeth for anger, whereas humans could mistake this for a smile.
Feeding Behaviour - Herbivores
Animals can be catagorised as either herbivores (plant eaters), carnivores (meat eaters) or omnivores (plant and meat eaters).
Herbivores - Examples of herbivores include cows, rabbits, deer and bison. These are all examples of vertebrate herbivores i.e herbivores which have a spine. The feeding behaviour of herbivores differs from carnivores:
- they spend lots of time eating - so they can get enough nutrients
- feed in large groups (herds) - so that the herd as a whole survives, and weaker individuals are killed
- constantly on the move - because they eat so much, they need to move to areas with more food
- they are good at avoiding predators - they have strong legs, are well camouflaged, their eyes are on the sides of their heads, many have pointed horns/hooves to fight off predators
A carnivore is an animal that kills and eats other animals. Examples include tigres, crocs, foxes and dogs. They:
- spend relatively little time eating - meat contains lots of amino acids, so they can eat less but still get the acids they need
- have excellent abilities to detect and catch their prey - they have eyes at the front of their heads so they can judge distances well, good hearing and sense of smell so they can detect their prey, powerful legs so they can catch their prey, sharp teeth and claws for catching and eating their prey
- they sometimes hunt in packs - they cooperate by surrouding their prey, they share what they catch i.e hyenas
- some hunt alone - they do not have to share their food (except with their family)
Reproductive Behaviour & Mating
To find a suitable mate, animals use courtship behaviour. Male birds will often strut around showing off colourful feathers; females have dull feathers (so that they are camouflaged when looking after their young)
Mating: Most animals do not mate for life. Animals that don't mate for life:
- Lions - in a pride of lions there is usually an alpha male that mates with all the females, which means that all cubs in the pride are his.
- Sea-lions - behave in the same way.
There are some species which are monogamous (they have just one mate). Monogamous species include:
Mammals care for their young in several ways:
- Pregnancy - a female mammal carries her young inside of her uterus before they are born. This provides the unborn offspring with protection and so vastly increases their chance of survival.
- Breast feeding - a female nourishes her young with breast milk. This provides a constant and safe place to feed.
- General protection - a female, and sometimes the male, keeps an eye on their young as they grow up.The young gradually learn from their parents how to look after themselves.
Birds also look after their young in several ways:
- Incubation - once eggs are laid, parents sit on them and keep them warm.
- Feeding - one/both parents leave nest to look for food, which they bring back
- General protection - building a nest, laying eggs which are camouflaged, and attacking of distracting predators.
Using Tools to Search for Food
It is accepted that humans are the most intelligent of all animals because:
- their ability to communicate using language
- their ability to use tools
Some other animals use basic tools to help them catch/eat food. Chimps are considered very advanced because they have the ability to:
- use tools
- make different tools
- select tools according to the task
- design new tools when they need to solve a new problem
For example, they will use sticks to poke into ant and termite mounds, and they use twigs to remove honey from bees' nest and leaves to clean their fur.
Over the last 14,000 years, humans have domesticated various wild species by using the principles of selective breeding. Animals include:
- dogs - trained to help hunt other animals for food
- horses - useful as they can be used for transport, entertainment and food
- herd animals like cattle, sheep and goats - provide constant food source. Also provide leather for clothing, as well as fur and wool for clothing and furniture.
In recent years, humans have used animals for medical purposes:
- new drugs are often tested on animal in a lab
- animals used in the production of vaccines i.e cows, sheep and chickens
- biotechnology has resulted in animals being bred that can produce drugs for human health. i.e sheep in production of factor VII, a blood factor for people with haemopilia
Many people anthropomorphise: they explain animal behaviour in terms of human emotions and characteristics.
Other people say that human and animal behaviour have nothing in common. For example, if a cat rubs itself against its owner, people might interpret it as being affectionate. In fact, the cat might be marking its territory or communicating hunger.
Many people feel very strongly that animals have the same rights as humans and that all testing should be banned, and that the use of fur for clothing is wrong.
Other people say that it is ethical, and often necessary to do experiments on animals - the only alternative would be to experiment on humans.
They say that testing drugs & medicines on animals is necessary to save human lives. However, the testing of cosmetics on animals is now generally seen as unacceptable.
Against animal exploitation:
- Animals are made to suffer unnecessarily when they are used in medical research.
- Fox hunting is cruel as they are torn apart by the dogs
- Intensive farming mehtods produce cheap food by cruel methods, such as keeping animals in cramped conditions.
For Animal Exploitation
For Animal Exploitation:
- Medical research has to be done, otherwise how would we find out whether or not the products were safe?
- Foxes are predators that kill lambs and chickens; fox hunting keeps the number of foxes down
- People need to eat and many cannot afford to spend lots of money on food. Meat would be much more expensive if animals were kept in less cramped areas, because there would be fewer animals to sell for meat.