Futher additional biology

• Bile - made in the liver but any excess is stored in the gall blader. It neutralises acid and emulsifies (breaks down) fat.

• Excretion - the removal of fluids and gases that are waste products of motabolism.

• Metabolism - chemical reaction that occur in the body to produce energy.

• Egestion - the removal of undigested food.

The  main roles of the kidney -

• To remove urea from the blood which is produced in the liver from the break down of amino acids.
• The adjustment of ion levels in the blood.
• The adjustment of water levels in the blood.

Ultra-filtration -

In a nephron, high pressure is built up water, urea, ions and glucose out of the blood in the renal artery and into the bowman's capsule. The glomerulus and bowman's capsule act like filters so big molecules like proteins and blood cells do not come out of the blood.

Reabsorption -

As the liquid flows through the nephron, useful substances are reabsorped back into the renal vein. All glucose is selectively reabsorped against the concentration gradient and sufficient water is reabsorped dependant on the level of ADH.

Release of wastes -

Urea and excess water are not reabsorped; they continue out of the nephron, into the ureta and down the bladdee as urine. Urine is then released through the urethra.

When someone is dehydrated, there is a decrease in water content in the blood, which is detected by osmoreceptors in the hypothalamus. The pituary gland releases more ADH and so the permeability of the collecting duct increases. More water is therefore reabsorped and a small volue of concentrated urine is produced.

When someone is too hydrated, there is an increase in water content in the blood which is detected by osmoreceptors in the hypothalamus. The pituary gland releases less ADH and so the permeability of the collecting duct decreases so less water is therefore reasorped and a large volume of dilute urine is produced.

Dialysis filters the blood mechanically. It has to be done regularly to keep disolved substances at the correct concentrations and to remove waste. Dialysis fluid has the same concentration of salts and glucose as body plasma so that they are not removed from the blood.

The barrier is permeable and just like the membrane in the kidneys, it only allows ion and waste substances, not big molecules like proteins. This allows waste substances like urea, excess ions and water from the blood to move across the membrane into the dialysis fluid which is then pumped out.

Kidney transplants can cure kidney disease however the organ may be rejected by the immune system as it attacks the organ with antibodies. To prevent this from happening, the patient takes drugs to supress the immune system and the donor's tissue type must closely match the receiver's.

Egg cells - to carry the DNA and to nourish the developing embryo in it's early stages. 

• Contains nutriets in the cytoplasm to feed the embryo.
• Once fertilised, the egg's membrane changes structure to stop anymre sperm from getting in so that the offspring has the correct amount of DNA.
• It contains a haploid nucleus, so that when the egg is fertilised, it will ahve the correct amount of chromosomes.

Sperm cells - to transport the male's DNA to the egg cell so their DNA can combine.

• They have lots of mitochondria in their middle section to provide the energy from respiration to the tail for it to be able to swim to the egg.
• It has an acrosome at the tip where enzymes that they need to digest their way through the membrane of the egg cell, are stored.
• It contains a haploid nucleus, so that when  is fertilises the egg, it will ahve the correct amount of chromosomes.

Stage 1 - day 1 - this is when the bleeding starts as the uterus lining has broken down and it released.

Stage 2 - days 4-14 - this is when the lining of the uterus builds back up again into a thick layer of spongy blood vessels ready to receive a fertilised egg.

Stage 3 - day 14 - this is when an egg is released from the ovary.

Stage 4 - days 15-28 - this is when the lining is maintained and if no fertilised egg has landed on the uterus wall, then the spongy layer of blood vessels break down and so the cycle starts again.

FSH 

• Causes an egg in it's surrounding cells (follicle) to mature in one of the ovaries.
• Stimulates oestrogen production and is made by pituary glands.

Oestrogen

• Causes the lining of the uterus to grow and thicken.
• A high level stimulates an LH surge but blocks FSH and is made by the ovaries.

Progesterone

• Causes the lining of the uterus to be maintained.
• Prevents the production of FSH and LH and is made in the ovaries.

LH

• Causes the follicle to rupture and so the egg is released.
• Stimulates remains of follicle to develop into corpus luteum and is made in the pituary gland.

During the menstral cycle, negitive feedback controls the different levels of hormones in the blood. For example -

• FSH stimulates the ovary to release oestrogen.
• Oestrogen prevents futher release of FSH from the pituary gland in the brain.
• After FSH has caused a follicle to mature, negitive feedback keeps FSH low so it doesn't make any more follicles mature.

An injection of FSH to help eggs mature, and an injection of LH to stimulate egg release -

• Pro's - it allows women who struggle to conceive, to have a better chance at doing so.
• Con's - it doesn't always work so it's expensive if it has to be repeated. Also too many eggs may be stimulated, resulting in multiple eggs being fertilised and therefore having twins.

IVF involves collecting eggs and fertilising them outside the womb with a man's sperm. Once they have grown into embryos, they are then placed back into the womans womb to improve the chance of pregnancy. FSH and LH injections are given before to stimuate egg production.

• Pro's - if it works then the infertile couple can have a child.
• Con's - some women may have a reaction to hormones given causing them to be sick etc. There have been reports of a increased risk of cancer due to hormonal treatment and lastly, multiple births could occur if ore than one embryo grows into a baby.

Surrogacy is where IVF happens and is then placed into the surrogate mother -

• Pro's - it allows the couple to have children if medicl problems stand in the way.
• Con's - the surrogate mum is legally the mother until the child is adopted so she may keep it.

• Allele - a different form of the same gene.
• Gene - a length of DNA that codes for a specific feature.
• Phenotype - the outwards characteristics that you show.
• Genotype - what alleles that make up your genetic code.

Haemophilia - where blood doesn't clot properly, caused by a recessive allele carried on the X chromosome. Dominant allele means you don't have the diesease but recessive means you do.

Red green colour blindness - where men are unable to distinguish between the colour red and green, caused by a recessive allele carried on the X chromosome. Dominant allele means that you do not ahve the disease but recessive means you do.

Bacteria reproduce by spliing in two so the number of bateria doubles at regular intervals meaning their growth is exponential. This means that if a nasty bacteria gets into the body, an inection can develop very quickly before your immmune system gets the chance to respond.

Louis Pasteur

• Based on the germ theory he invented pasteurization where bacteria is removed by boiling and then cooling liquid.
• Discovered that microbes were responsible for souring alcohol.
• He proved that microbes were attacking healthy silk-worm so developed a method to prevent their contamination.
• His experiament was where he had 2 flasks, one with a straight neck to that air could get in easily, allowing bacteria to grow in the broth. The other had an 's' shaped neck to when air got in, the bacteria got stuck on the curve, proving that there is bacteria in the air.

Aseptic technique - methods of handling sterlie equipment and microorganisms so that they are not contaminated with other microorganisms.

A dead of weakened version of the pathogen is injected into the blood. Antibodies on the white blood cells attack antigens that are on the pathogen which destroys the pathogen. Your body can now produce antibodies if you get the virus in the future as it has already learn't how to.

Edward jenner was the first person to vaccinate against a disease called smallpox. He knew that people with cowpox didn't get smallpox so he put a scab from a girl with cowpox into a boy's cut who has smallpox and at first he was a bit unwell but then he didn't catch smallpox when he was exposed to it.

The cowpox antigens triggered the boy's B-lymphocytes to produce antibodies. As smallpox had some of the same antigens as cowpox, his immune system was able to quickly produce antibodies to prevent him from getting the disease.

• Pro's - epidemics were able to be prevented if a large percentage of the population were immunised. Some dseases such as smallpox have been completely wiped out due to immunisation.
• Con's - sometimes immunisation doesn't always work and doesn't give you immunity. Also it can cause a bad reaction however this is very rare.

They are identical antibodies made in large quantities and each type is specific to a particular disease.

• Antibodies are produced by B-lymphocytes.
• You need B-lymphocytes to divide quickly to produce more antibodies to kill a disease so it has to be fused with a tumour cell to create a cell called a hybridoma.
• Hybridomas can divide quickly so produce lots of identical antibodies called monoclonal anti bodies.
• Monoclonal antibodies are able to bind to any type of antigen you want and so they are really useful.

Detectng cancer or blood clots -

• Monoclonal antibodies carry a radioactive substance so when they are injected into the blood they attach to cancer cells to form blood clots so that a scanner can detect where the cancer is.

Pregnancy testing -

• The hormone HCG which will appear in urine if pregnant, binds with monoclonal antibodies that are attached to blue dye beads. Then the monclonal antibodies travel up the stick to the first window where there are immobilised antibodies. HCG then binds to these so blue dye is released so one line is shown. At the second window the same occurs just to ensure the test is working properly.

Treating cancer -

• In chemotherapy, the chemicals attach to antibodies and target cancer cells as well as healthy cells. In monoclonal cancer drugs only attach to cancer cells so less drugs are used.

Plants produce chemicals to defend themselves against pests and pathogens. Some of these chemicals can be used to treat human diseases or relieve symptoms. For example -

Aspirin

• Used to treat pain and lower fever.
• Found in the leaves the bark of willow trees.

Crops are lost each year due to pests and insects, weeds and  pathogens,

• Fruit flies feed on fruit so can reduce the yeild of fruits massively.
• Weeds grow next to plants to compete for nutrients so if the plant doesn't get enough then the yeild will decrease.
• Pathogens take the plant's energy so it won't develop alot of fruit, making the yeild lower.
• Pests also add to the cost of producing food as money has to be spent on pesticides.
• Low crop yeilds can drive up the price of food for consumers.

Plants

• In leaves the stomata opens in day light and close at night to stop exchanging gas and prevent water loss.
• The head of the flower opens in the day so that the bees call cross-pollinate and closed at night due to evoloution.
• Plants can respond to the change in a day's length which allows more germination. This is called photoperiodic.

Humans

• Circadian rhythms go in a 24 hour cycle
• Sleep patterns occur based on light intensity which is used to control the hormone melatonin which makes you sleepy. When it is dark, melatonin increases.
• The body's master clock is a group of nerves in the brain that controls the production of ADH which increases at night which reduces urine production.

Behaviour is how an organism responds to their environment that will allow them to survive. All behaviour is either learnt or innate or both. Genes and the environment play a role in influencign behaviour.

Innate behaviour - an automatic response to a stimulus that is immediate whether they have experianced the situation before or not.

Habituation - a learned behaviour where animals do not respond to the same stimuli as long as it doesn't cause any harm. It is based on their past experinces, that will allow them to survive.

Imprinting - when an animal learns to recognise it's parents and instinctively follows them, so is both learnt and innate.

Operant conditioning -  It uses 'trial and error learning' where the animal actively learns to associate an action with a reward or punishment, so they do it more so that they are rewarded more.

Classical conditioning - when an animal passively learns (without trying) to associate a neutral stimulus with a signifficant one. This response is automatic and reinforced by repitition.

For example, sniffer dogs are trained to detect drugs so that everytime they come across drugs they are rewarded, so the more often they do find drug, the more rewards they get, resulting in them actively wanting to find drugs

Communication between individuals in beneficial in many ways -

• It can help keep the group close together.
• If one animal sees a preditor then they can make others aware.
• Mood is communicated to avoid unnecessary fighting.
• Baby animals are able to communicate their needs to their parents.
• Communication can allow preditors that hunt in a pack to organise their attack.

Sound - a form of verbal comunication through language. Whales and dolphins communicate using low-frequency sounds over long distances. Birds calls are used to declare their territory, to attract mates or warn of preditors.

Chemicals - pheramones can be released by an animal to tell others where it is or where it has been. They scents can be used to mark territory or they can act as sexual attractants.

Visual signals - facial expressions mean different things in different species to communicate with eachother. Most animals are able to communicate through mody movements like posture and gestures. For example to threaten others, chimps stand or raise one arm and bees do a waggles dance when they return to their hive with food.

Ethology - the study of animal behaviour.

Tinburgen - he wanted to investigate whether baby gulls had to specifically peck on the red spot on the beak for food or if it could be anywhere on the beak. He made cardboard gulls with different coloured spots but the baby gulls pecked at the red one the most, concluding that it is an innate behaviour that helps them to find their food.

Lorenz - he wanted to investigate why baby chicks recognise their mother and follow her around. he took 2 sets of eggs, one hatched with their mother and the other set without. The first moving object that the chicks in group one saw was their mother and for group two it was Lorenz himself. Lorenz was followed by the chicks from group two just like group one foloowe their mother showing that the geese had imprinted.

Dianne fossey studies mountain gorillas and Jane goodall studied chimpanzees. They both spent their time in their natural habitats so that they didn't disturb their behaviour. The y observed and recorded their findings to see that both animals were social and lived in groups. This was shown by the way the apes kept eachother clean, and hgging eachother and they had heirarchy where dominent males were at the top to prevent unnecessary fights.

A choice chmber is an enclosure with 4 different environments where animals are able to freely choose what environment they wish to be in.

It is used to investigate behaviour in animals as we are able to see not only there prefered environment but alos their innate behaviour.

Courtship behaviour - where a male tries to impress a female in hope to sexually reproduce together, for example, daning, or showing brighly coloured parts of their anatomy. It is important because it allows genetic to be passed on and for evoloution to occur.

Spechies - a group of similar organisms that are able to reproduce to produce fertile offspring.

Monogamy - staying with only one mate.

Courtship behaviour ensures successful reproduction as it allows animals to -

• Recognise members of the same spechies.
• Identify a mate that is capable of breeding.
• Form a pair bond.
• Synchronise mating.

Plant communication - where the plant goes a bright colour to attract an insect to pollinate it.

Plant communication with animals -

• Petals are brightly coloured and they produce chemical scents to attract insects.
• Bright fruit means that it is ready to be eaten by animals that produce faeces that spread it.
• They produce poisonous chemicals to deter insects.

Plant communication with other plants -

• Acacia trees produce chemicals to edter herbivores but only do this if it is being attacked.
• If it gets attacked  by lots of insects, the leaf produces ethene to warn other plants.

Co-evoloution - when 2 spechies evolve and change together as a result of changes in the other organisms. For example, a wasp visits orchids to collect food, but they are more likely to visit a female looking orchid in attempt to reproduce with it. The wasps picks up its pollen from the orchid, which the orchid likes as it is more likely to be pollenated so will evolve to look more female.

Humans share a common ancestor with apes. We are similar as we are both able to communicate and use tools.

Evidence in fossils -

• Spechies starting to walk more up-right.
• Spechies getting taller with longer legs.
• Arms get shorter in spechies.
• Skull size increases as the brain size also increases.

Evidence in tools -

• Using more tools that have developed in complexity.
• Tools are able to be radio-metric dated by using surrounding rocks.

To work out the age of a fossil, carbon dating can be used when looking at wood only but radio-metric dating can be used for rocks and the earth above and below the fossil.

Types of fossil -

• Ardi - 4.4 million years ago - would have developed feet in order to climb but his arms would have long arms and sort legs so she was more ape than human. Her brain size was about the same as a chimpanzee's. The structure of her legs suggested that she walked up-right like a human, which was supported by her hand bones also suggest she didn't use her hands to walk like ape does.
• Lucy - 3.2 million years ago - would have had arched feet to walk rather than climb with no ape-like big toe. The size of her arms and legs were between an ape and a human however ther barin was slightly larger but still similar to the size of a chimp's brain. The structure of her legs and feet suggest that she walked more up-right in a more efficient way that Ardi.
• Turkana boy - 1.6 million years ago - was found by leakey and his team of scientists in 1984 and has a mix of both human and ape-like  features such as his short arms and long legs being more like a human than an ape. His brain size was also bigger than lucy's, more like the six=ze of a human brain and the structure of his legs and feet suggest that he was even better adapted to walking than lucy.

Mitochondrial DNA is only passed down from the mother as it is found in the cytoplasm of the egg cell. However it mutates faster than normal DNA. It shows us that we descended from 'african eve' and this is because there is an unbroken female to female line from our ancestors down to us. The discovery of african eve means that homo sapiens must have evolved from africa then spread across the world.

Advantages of Mitochondrial DNA -

• It is more common so is easy to rely on.
• It is more stable so does not decay.
• Their high mutation rate means that we can be more precise with aging.
• It only passes down the maternal line so making links is easier.

Migration caused changes in human behaviour as they encountered new environments so they needed to adapt in order to survive.

The coast of the near east and asia -

• New settlers here had to change their diet to eat shell fish and seafood which ment that they had to invent new tool to take the meat out of their shells.

Australia -

• Rainforest settlers started to eat fruit that were on the trees which ment inventing new way of getting the fruit down.

Europe -

• The settlers changed their diet to eat new meat and plants that they found as many were large so they had to make new ways of hunting like in groups. As the climate was colder, they had to build shelters and used animal skins from the animals that they hunted to keep them warm.

Biotechnology - the alteration of natural biomolecules using science and engineering to produces goods or services.

Fermentation - any process where microorganisms use an external food source for energy.

Aseptic technique - keeping sterile.

The fermenter is steralised with steam to keep in aseptic, killing all unwanted microorganisms. Then the microbes are added and the mix is constantly stirred by the paddles to evenly distribute the mix. Sterile air is pumped into the fermenter to provide oxygen for respiration. Cooling jackets keep the temperature at constant temperature so that the yeild of the product is at it's maximum. The PH of the mixture must be correct in order for the microorganisms to thrive and so that the enzymes are not denatured.

Mycoprotein is food that is made from fungi which is used to make meat substitutes such as quorn. The fungus - fusarium - is grown in fermenters using glucose syrup as food. It respires aerobically so oxygen is supplied to it. It has benefits as the yeild is higher in a less amount of time, but it also has health benefits as it contains less fat but more fibre, protein and vitamin B. However it is expensive andthe consumers are unawarre of where the product comes from or what it specifically is.

Bacteria is able to be fermented from milk to make yoghurt. Milk is pasteurised then cooled and lactobaillus bacteria is added and the mixture is incubated in a fermenter. This turns the lactose sugar into lactic acid, causing he milk to clot and solidify as yoghurt. Flavours and colours are then also added ready for it to be sold.

Advantages of using microorganisms for food production -

• Bacteria and fungican grow quickly.
• They are easy to maintain and look after.
• As long as you have the right equipment, it can be grown anywhere despite climate.
• It is cheeper than other methods.

In biological washing powders -

• They contain enzymes that are able to break down stains such as carbohydrates fats and proteins as theese are all insoluble but the products of the enzyme-controlled reactions are soluble so can then be dissolved in the water.
• They're more effective at  low temperatures  and at PH of 7. Places that have hard water the calcium may damage the enzyme as it is too alkali, so may not remove the stains as easily.

Cheese -

• Made from renney which is on the inside of a cow's stomach that clots the milk as it contains a protein called chymosin and because vegetarians don't want to eat it, veggie cheese is made using chymosin from GM microorganisms. The genes responsible for chymosin are extracted and put into yeast cells to be grown on an industrial scale.

Sweets -

• The enzyme invertase/sucrase converts sucrose into glucose and fructose which is sweeter, so less sugar is used so it's cheeper. Invertase is naturally produced by a yeast.

Q - How is GM insulin made?

A - A plasmid is removed from the bacteria and an insulin gene is cut from the human chromosome using a restriction enzyme. This leaves one of the DNA strands of insulin with unpaired bases called sticky ends. The plasmid is also the cut open with the same restriction enzyme leaving sticky ends on that too Now the plasmid and the human insulin gene can be stuck together using the ligase enzyme to form a recombriant DNA. This is then inserted back into the bacteria to assexually reproduce and grow in a fermenter.

 An example of genetically modifying plants -

Purple tomatoes contain snap dragon genesthat makes it purple. The genes cause the production of flavanoids which help people live longer and may reduce the risk of getting cancer.

Crops can be genetically modified to be resistant to insects. A bacterium called bacillus thuringiensis which produces a toxin/poison that kills the insects that are harmful to crops. The gene for this toxin is inseted into crops like corn and cotton which then produces the toxin in their stems and leaves, making them resistant to insect pests. As is specific for insect pests, it will not harm humans or other animals but long-term exposure to these crops are not yet known. The insects are then constantly exposed to the toxin so may become resistant to it so other insecticides are also usedso that this is prevented.

People in developing countries do not have enough food . Biotechnology could help as crops can be genetically modified to be resistant to pests and so improving crop yeilds, they can also be genetically engineered to grow better in drought conditions again improving crop yeilds. Also they can be engineered to combat diseases so that it is able to produce more things that are beneficial. However t is argued that povery should be targeted first and GM food is expensive.

The flavanoid in snap dragon flowers have anti-oxidant effects which are thought to protects against cancer and heart disease, however they change the colour of the fruit and people worry about the long-term effects of GM crops.

Due to the world's increasing population, the rate at which we produce food must also increase at the same rate in order to feed everyone, with correct balance of nutrition, so that everyone has the same amount of food. This is known as food security.

How to increase food production -

• Reducing pest numbers - killing insect pests means that crop yeild increases. Also crop rotation which means growing a cycle of diferent crops to stop a build up of pests attraced to that crop from building up in one area. Biological control may be used so instead of using chemicals, preditors of that pest can be released into the area affected.
• Selective breading programmes - where human select the best plant based on what we want from them. The parent plant with the best characteritics are selecte and bred with eachother, then the best offspring are selected to breed. This process is repeated over generations to develop the desired traits.
• Genetically modifying plants - make the plants resistant to insects to increase crop yeild.

Biofuel is made from biomass which is made from plants or animals or their waste products. Examples include -

• Biogass - microorganisms decompose waste materils or plants to produce biogas which is 70% methane and 30% carbon dioxide. It can burnt to power a turbine that generates electricity or to heat water to create steam to heat central heating systems. It can also be used as fuel for cars and buses.
• Biodiesel - an alternative fuel which can be used in vehicles. It is made from vegetable oils, animal fats or waste cooking oils.
• Ethanol - can be burn as a fuel but it is cleaner than petrol and diesel, producing fewer polloutants. It is produced by using yeast to ferment glucose. Materials like sugar cane, corn and barley can be used for that glucose. Cars can be adapted to run on a mix of ethanol and petrol which is known as gasohol.

They are a greener alternative to fossil fuels as they are sustainable. They can be replaced easily with new crops, but will eventually run out. The plants grown remove carbon dioxide from the air via photosynthesis which counterbalances the release of carbon dioxide when burning the biofuels. They do not produce alot of sulphur dioide which is acid rain, however alot of land is needed.