hey guys in this video we're going to know that everything you need for your wge sea biology papers hit now if you haven't got it already this is the perfect time to donate the free version code for my website and use it with this video to tick off the bits that you don't know and identify where you've got gaps in your knowledge you can then follow that up by doing the predictive papers are doing the workbooks are the multiple choice questions to try and fill in those gaps good luck guys so Pia I know you the every single step of the way polonaise develop taxonomy which is the study of grouping living things together we can see on our evolutionary tree here that some things are very closely grouped together and get the other things you actually have to go quite a long distance he develops naming system where we have each organism hires a 2-part latin name and this will tell us how closely related they are it's a bit like them having a first name and a second name at genis and then a species the genus will be the wide overarching type of thing and then the species will be exactly what thing it is with each new development in biology with each new development in genetics we understand more and more about classifications so our taxonomy and our evolutionary tree is evolving all the time the three domain system divides everything in life into three groups eukaryotes bacteria and archaea eukaryotes are things that have nuclei an ecosystem are the animals plants everything living within a certain area the community of the plants or animals that live there and they're all dependent upon one another they cannot survive without each other for example the animals eat the plants they can't survive without doing that and the plants rely on the animals to dispute their seeds to survive and refugees a species needs food water and sometimes were not always a mate abiotic and biotic factors are things that are going to affect any organism Abel took on nonliving factors such as light intensity temperature water levels pH iron levels wind carbon dioxide levels and oxygen levels biotic factors are going to be living factors such as food predators and pathogens an increase or reduction or removal or introduction of any of these factors can have a dramatic impact on a community for example the introduction of a new predator or new pathogen called white outer community an increase or decrease in the temperature could mean that there are organisms food source is gone all organism can't survive in that environments and plants and animals aren't going to be able to survive without sufficient levels of carbon dioxide and oxygen animals need to adapt to our environments so that they can survive cacti are well adapted to a desert environment because they have shallow roots they have spines to prevent them being eaten and they can store water in their leaves snow foxes are white so that they blamed in they have small ears so that they don't lose heats was a bejeezus service area and they have a very thick coat if you want to investigate what grows and it feels you can use a quadrat which is going to be lets say a meter square you throw that on the ground and count what is in there randomly moving it around the field so that you get a wide coverage you're going to need to estimate the size of the field so that you will can work out how much area there is work out your plant population per area that you even measured and then multiply that up to cover the entire field a transect is it more ordered you start at a point take a line and then take measurements at every single point along that line this could be saved from a hedge moving away so that you are varying things like the light intensity or distance on water DNA is a long strand of deoxyribonucleic acid made of lots of letters a's t's c's and g's and these twists round into a double helix this double helix is still ridiculously long so it's further twists rounds so there's in a chromosome and this chromosome is located in at the nucleus of a cell in mitosis we go from one parent cell to identical daughter cells the first thing that needs to happen is that the DNA in the nucleus needs to condense into chromosomes and then they need to line up down the middle once they're all lined up down the middle and all the checks are taken place to make sure that chromosomes aren't gonna go astray they can start to be pulled apart to either end of the cell new nuclei will form and then they'll separate into two identical daughter cells in meiosis we are going to have two divisions so our chromosomes will line up they will sort themselves down the middle there will be a little bit of crossing over going on so they will swap chunks of their chromosome to increase the genetic diverse they will divide into two then they will line up and divide into two again and you'll notice that each of the cells have half of a number of DNA as the parent cell mitosis will lead to two identical daughter cells whereas meiosis will later for different daughter cells you can remember mitosis those two t because you have the DNA mitosis Easy's things like growth or repair well as mices is used for sexual reproduction so these are going to be gametes in mitosis we are going to end up with diploid cells and in meiosis we are going to end up with hack right sense haploid cells having half the number of DNA as the original cell in women the gametes are eggs and in men the gametes are in a plant we have eggs still and that is in the stigma and then the male gametes in plants are pollen and that is on the statement cancer is when cells begin to divide uncontrollably this is going to lead to you lumps which for most people some people is the first sign that something is wrong and these lumps can be divided into two groups but 90 means and malignant tumors benign tumors are slow and IgM really harmless things like warts or moles are benign tumors and having a lump on your skin generally doesn't do you much damage the problem is when there are malignant tumors these are false growing they are aggressive and they're mobile so I don't mean the water on your arm or the mole on your arm is gonna get up and start moving around I mean cells are gonna move throughout your body cells from the initial lump are gonna jump into the bloodstream and move somewhere else and they kids s up Shima's lumps in other places and wahla lump on your skin germany won't do much damage a lump in your brain a lump in your liver or a lump in your lungs can do quite a lot of damage there are risk factors involved in cancer and there are a lot of things that we have in control of smoking has large implications in lung cancer diets are good diets can reduce your risk of bowel cancer whereas if you don't eat much fruit and vegetables then you are putting about em at risk of cancer the amount of time we spend in the Sun can affect your susceptibility to skin cancer and unprotected sex can leave your risk of cervical cancer stem cells are fantastic things because they're things that have the potential to turn into any other type of cell they have a number of different uses for example if you're treating Parkinson's disease they can be used to grow new brain cells if we talk about brain or spinal injury bone injuries then they can be used to grow new bones to fill the gap but if we have organ failure we can grow new organs or parts of organs instead of waiting and making some weight on the incredibly long transplant waiting list if we want to make stem cells then we take a nuclei out of an Excel we take nuclei from the patient cell and insert that into the empty egg there F and then start to develop into an embryo from this embryo the stem cell are then removed and stem cells are turned into new cells this does come with quite a lot of controversy because human embryos are going to be created and then destroyed and there were lots of religious objections this people to saying that life M starts with embryos are created and people object to the destruction of embryos DNA is made from different bases that fit together so we are always going to have a connecting to T we're always going to tell C connecting to G this is always always always going to be the case it has a sugar phosphate backbone and they return österreich all away around the outside there are chair days it is a double helix you see that the green is always connected to the yellow eight TCG the blue is always connected to the orange and it's going round in a helical or a double helical structure gene is a stretch of DNA the case were characteristic genome is all the genes in a body all the genes that you have each three-letter sequence of DNA is going to code for amino acid so here we have a G a we starts off with a thorn G and point a so that DNA sequence is going to code into the amino acid arginine the next three along CTG are going to code into leucine and this will keep going until eventually we have a long amino acid chain this can then fold up in very complicated ways until we get a protein that will look something like that and proteins were responsible for basically everything that happens in your body there are the hormones there the enzyme there the cell walls everything is a protein or dependent upon a protein and these proteins are very very specific and enzyme substrates active sites is going to be very very specific to the substrate so if there is a mistake in our amino acid chain if something is missing or if something is wrong we put the wrong amino acid in there then our enzyme our protein is going to fold up wrong with the mutation is going to have caused a change in the protein which can then have a massive impacts on functions meaning that it might not work properly meaning that it might not break down what it's supposed to break down meaning they might not function in the correct way there is a massive amount of DNA in each of ourselves and only some of it is useful so say this section here might be non-coding which basically means it's like junk DNA you're just getting in the way a gamete is going to be a sex cell so in the human side is a sperm or other egg chromosome is bundled up DNA alleles are different versions of genes Domino means you'll need one gene to express characteristic recessive means you need two identical recessive genes to express characteristic homozygous measure genes the same heterozygous major genes a difference genotype is what genes you have phenotype is the collection of characteristics that you have we can work out the chances of a disease or a phenotype being passed on by doing a genetic cross these were things I think should be laid out very formally in Bray population mothers genotype big R little R mothers feeling tribes carrier father's feeling type big R little R father's phenotype a carrier mother's gametes now we can meet some mother's gametes over here and the father's down here and then fill in these ones down and these ones across so the mother then this one down the father this one and then the father this one then offspring are going to have dominant dominant today they're homozygous and non suffering two of the potential offspring or half the potential offspring are going to be heterozygous in the carrier and then out the offspring one in four them has chance of being a double homozygous recessive and being a sufferer polydactyly it's a condition where the people get one two three four five six little adorable baby fingers and eat is dominant so here we have a mother who has two homozygous recessive and boy fingers and a father he has a dominant and recessive and has six fingers we can feel in the genetic cross and we can see somebody who has these dominant disease if they have one gene they'll pass it on a fifth or that officer has a 50% chance of also having polydactyly cystic fibrosis is a recessive disease so as we saw in the first example if we have two parents that are carriers there is a 1 in 4 chance of an offspring having at the disease if only one parent is a carrier then their chance of the baby having my sister erases are virtually nothing apart from very new mutation and transfer them being a carrier or 50% if your family has a known genetic sees or if you have a child that high like genetic disease you could opt to have IVF and before your embryo was implanted back into you you could have it's screen so embryo screening or pre-implantation genetic diagnosis the advance shoes to this that you can test the embryo so only put back healthy embryos so that chances are the baby born is going to be healthy and is going to survive or you can have an embryo implanted which could help be a match a genetic match for a sibling already born the disadvantages of this is that embryos are going to be created and destroyed and some people have religious objections this your chromosomes are in the nucleus and you have 23 pairs so that is 46 in total I say 23 pairs because you're going to get one copy from the mother on one copy from your father so you'll have 2 cups of chromosome 1 2 cups of protein - 2 cups of chromosome 3 2 cups of chromosome 4 one from your mother and one from your father this will allow for you to be homozygous or heterozygous for dominant or recessive genes if you have inherited two X chromosomes you're going to be genetically female if you have inherited an X and a Y chromosome you're going to be genetically male we can genetically modify plant DNA so we can take our DNA we are required characteristic whether that is a drought resistance gene so there are countries that don't get much rain and very very susceptible to droughts can survive that better so their crops are going to grow better whether that's a gene which produces a vitamin so that countries that don't have a good few security where food is shortage where people are dying because I'm not getting white man's means we can engineer the food the rice that they're growing so that it produces more vitamins so it's healthier so that less people are going to die or whether it's just pesticide resistance or the ability to resist being eaten by pests being eaten by bugs say that yields are higher we can take that gene and put it into our original plant DNA producing a genetically modified plant we can add in the new gene to the plant DNA we can produce seeds and then the farmers can grow vases and the plants will have this a new desired characteristic some people don't like genetically modified plants because they think it's interfering with nature genetic engineering has brought around some fantastic advances one of the most useful of this is the way we produce insulin these days previously in Qin used to be harvested from pig sales and that's what people had to inject it wasn't very good and it wasn't very efficient these days we've taken the gene for insulin we've taken a bit of bacterial DNA and with the original DNA has our side characteristic and bacterial DNA reproduces really quickly the insertion of the gene for insulin into the bacterial DNA means that the bacteria are now producing insulin so we are now producing large amounts of human insulin which is a really important point quickly and safely this is much much better people than having to inject Pig insulin it's made things much cheaper much faster and much safer if you know that pair of identical twins you'll know that they are not exactly the same even though their genotypes are the same while they have identical genes their phenotypes their characteristics and how they look are going to be very different because your phenotype is influenced by lots of different things firstly your genotype so that's your DNA your genetic information and your environment this is going to natural variation in a population things are going to lead to variation in a population are going to be influences like diet exercise and personal choice the advantages of sexual reproduction is that you're get a genetically diverse population which means they're going to be better protected from diseases the counsellor is a disadvantage of asexual reproduction is that you're going to get a genetically identical population so that if a disease comes along and one plant is susceptible to ants of all plants the whole revelation or animals are going to be susceptible when they're all going to be worked out at once an advantage of asexual reproduction is that there is only one parent meaning that the plant or animal doesn't have to wait around for a mate to turn up whereas with sexual reproduction a mate is required and sometimes this can be quite hard to find especially in sparsely populated locations another advantage of asexual reproduction is that their energy is conserved and what I mean by that is that the parent is putting all of its energy into conserving its ownit genes so this is like The Selfish Gene it wants its genes its genetics to be continued as opposed to continuing putting energy into something that only has half or its genes making new copies of cells involves copying DNA over and over again and if you try copying something down thousands millions of times eventually they'll become a mistake and this mistake might happen once and then get forgotten of this mistake might be copied over and over and over again and if it gets copied over and over again we've got a mutation and we've got a natural selection all of these changes added together these small changes these big changes this is our theory of natural selection of evolution of gradual change happening over time this theory thought up by Charles Darwin that means we are more suited to our environments a Darwin's theory is that life all life that we know these days has evolved over the past 3 billion years from the first life they're very very simple unicellular organisms that's what in that slushee puddle and the way this evolution happens is by natural selection so that random mutations in genes nice and natural variation in a population so that can be small things like different hair color different eye color or big things like how tall people are so for giraffes being tall is quite an important things it means they have access to a larger range of food sources an individual's characteristics which make them better suited to the environment and more likely to survive and reproduce whether this is tall giraffes or finches with difference 8 beaks or moths that have gone black or gone white and the genes for these useful these desirable characteristics will be passed on to the next generation evidence for evolution comes from fossils I'm not everything at least was always because fossils come form of the hard parts the bones the soft bits are just going to decay away so won't leave the fossils and we can see evolution happening with bacteria because they multiply very quickly 20 minutes in some circumstances so we can see changes adaptations for natural selection being passed on and happening very very quickly fossils can show us changes that have happened and how different animals are related from these we can use or draw an inflationary tree showing us how closely things are related to things and more March in Terraria closely related and the point where they branch off that's where they became genetically distinct when Darwin proposed his theory of evolution it was very controversial there were lots of religious objections this is because he was saying that the earth was billions of years old whereas that's not what it says in the Bible he was saying that we were evolved from monkeys are evolved from primordial soup and that's not what it says in the Bible an alternative theory at the time is that acquired characteristics say for example if you dyed your hair blonde during your lifetime and he had a baby while your hair was blonde your baby would have blonde hair Wallace worked with Darwin they published a paper together and Wallace was very important when were talking about speciation geography mendel works with sweet peas and he discovered or was the precursor to discovering genes or units of information that um trans inherited units of information I think we can take a second to appreciate how thoroughly cute these little guys are before we starts to apply the serious issue of selective breeding selective breeding is breeding an animal for a particular characteristic it happens with dogs it happens with cows with horses with cats with chickens any animals that we keep and we look in the particular characteristic have probably undergone selective breeding and the advantages are is that you hear animals which have the desired characteristic whether it's the very flat face of a park or horses that run fast or cows that produce a lot of milk it is important commercially that dairy farmers have cows that produce a tall milk that dog breeders have dogs that look cute however the disadvantages to this is if you have a healthy animal who doesn't display the side characteristics for dairy farmers they are looking for cows that produce a lot of milk these obviously going to be female cows so any male calf's they're born they are healthy animals but they are not showing desired characteristic so they're killed um dogs that don't show the desired characteristic can be purchased sleep even though there are perfectly healthy animals thousands of dogs cats each year are killed just because they are not cute enough or do not look like the industry standard the desired characteristic can lead to long term health problems for their animals I've chosen the Pug as the example here because of the large number of folds on their face it squashes their little nose and it gives them a long-term breathing problems dogs like me Labradors are very susceptible to things like arthritis and dogs like we did in which backs though desired characteristic is a mutation so any dogs that are born without the which bag can be put to sleep and then lastly we have a lack of genetic diversity within the population so when we're talking about breeding this can lead to a lot of inbreeding we're brothers and sisters are bred to get the desired character mystic which is going to lead to recessive bad mutations coming out more often in the population it also means they're going to be more susceptible to any diseases that are going to be around because they don't have the genetic immunity when a single species of animals gets geographically separated and this could be because there were different islands or there could be a mountain range that pops up in between them then we had known end up with a situation when we have speciation where one species leads to various different species and this is called speciation Darwin saw this when he was over in the graph of the violence the finches small in birds all started off as one population one species but as they separated out on to the islands of those they got separated from each other they became quite different the main difference was in the shape and length of that beaks as they became more adapted to the food sources on those different islands so ever had to dig down deep to get the food or whether the food was on leaves whether it was hard space where the food was easy to reach acting divided very very rapidly bacteria is happy has lots of theatres lots of space and nutrients is going to divide roughly every 20 minutes this allows singing mutation to spread through the population really quickly this is gonna rule out antibiotic resistance to really easily develop and spread due to brandy mutations if those weren't in mutations that mean that the bacteria didn't get killed by antibiotics they're going to be flexible by natural selection I'm actually easily passed from person to person or from an animal person or from an animal to animal which means antibiotic resistant bacteria is going to spread it really easily penicillin has saved many millions of lives probably yours at some point definitely mine because before penicillin before the widespread use of antibiotics people died of very very common things koenings hospital to have a simple operation most of the time was lethal but for widespread use of antibiotics the smallest infection could kill you mr sa is a bacteria that is resistant to most antibiotics now this happens on your skin is there on your skin all the time if you go into hospital abrasion you'll get swapped for it to find out a few habits but if you do have it underneath an infection with it there are very few antibiotics they can use to treat it the development of new antibiotics is very slow partly because we've looked for a lot of these in a lot of places and partly because raping new drugs is very very expensive so companies are going to spend their time spend their effort and their resources looking at drugs that are going to make them a loss of Mullings drugs that people have to take every day for heart disease or diabetes antibiotics you take once for maybe seven days and then you don't need them again so they don't necessarily make pharmaceutical companies lots of money but they will cost lots of money to develop nervous system is incredibly complex and is overlaid on our spinal and muscular system it consists of the brain spinal cord which today are going to make the central nervous system or CNS and all the neurons the receptors and effectors when you pick up stimuli that signal needs to travel from where you pick up so your fingers all the way up to your nervous system your central nervous system sometimes just stopping at your spinal cord and then coming straight back again that is going to be a reflex this is gonna happen when you touch something hot so you move your hand away without even thinking about him other time something is going to happen the signal grabs your brain you'll think about it and then you'll decide to move the nerve cells involved in this I've a really long so this cell body here is incredibly long and this can send a fast electrical signal however when we come transfer a signal from one nerve cell to another nerve cell things slowed down a bit because they have to cross a synapse this is going to be a slow chemical signal as the chemical has to be released diffuse across channel and then we picked up and then initiates another electrical signal homeostasis is the maintenance of a constant internal environments and to keep your body functioning properly we need to control our blood glucose levels our water levels and our temperature here we have male and female an endocrine system the purity guard is in the brain the roid is in the neck your Drina Browns when the kidneys pancreas is hiding find stomach ovaries our right hip level and then testes her Willy's penis the testes produce testosterone which has the effects of growing muscles making the balls and penis drop and grow larger increasing the rate of hair growth Eastern is producing the over that is responsible for the maturation of eggs and the menstrual cycle the pancreas produces insulin which is important focal ating blood glucose levels the adrenal glands produce adrenaline which is important for our fight-or-flight response the thyroid produces thyroxine which is important in regulating our metabolism the pituitary gland is very busy among other things it produces follicle stimulating hormone FSH and luteinizing hormone LH the brain is the control center and that's going to be assuming signals to various parts of the body for example to the pancreas which is responsible for producing insulin and affect his muscles are going to do things like moving for example shivering and then glands are going to be responsible for the production of other hormones control of blood glucose is very complicated after a meal has been eaten a blood glucose levels start to rise this is picked up by the pancreas the pancreas produces insulin which is sent out into the blood the insulin in the blood stream is going to cause our body cells to start to remove glucose from the blood liver and muscle cells can take the glucose and convert it into glycogen and store it removing glucose from the blood will cause blood glucose levels to fall if blood glucose novice gets too low this is also picked up by the pancreas the pancreas or starch produce glucagon the glucose has previously been stored in muscle and liver cells starts to return to the blood the most complicated part of this is getting all the names right the stored form of glucose is glycogen glucagon will convert that into glucose and this returning the glucose will whose blood glucose levels to rise again there are two different types diabetes type 1 and type 2 in type 1 diabetes the pancreas of them properly so it doesn't produce the right amount of insulin in that type 2 diabetes cells starts become insensitive to insulin symptoms for both are going to be a loss of whites and increased needle we being very thirsty blurry vision fatigue so being very sleepy and hunger treatment for type 1 diabetes is going to involve intern injections type 2 diabetes it's going to be controlling diet exercise bacteria divide very very quickly from 1 into 2 into 4 into 8 into 16 a good bacteria a happy bacteria a bacteria that's got lots of nutrients and is happy with what it's doing we'll divide roughly every 20 minutes so that very very quickly you'll go from one rack here we have 10 millions of bacteria so that you can become very ill former and ingesting from getting in the carts from getting or skiing just a single bacterium because I you divide very very rapidly a pathogen is a microorganism that causes disease for example we can own viruses bacteria fungi or protestors and this can be spread in a number of different ways they can be spread in the air for example by coughing they can be spread by touch for example if you have bacteria on your hands or you have bacterial virus on your hands and you touch table and someone else then touches that same table they can be sprayed it through blood sexual fluids or they come in transferred a viral vector like viral mosquito bacteria are going to make you feel ill because they produce a lot of toxins so they'll give you things like food poisoning viruses will make you feel ill because when they reproduce they cause massive cell death here we have our bacterial cell which has its cell membrane controlling what goes in and out the cytoplasm where most of the reactions take place the chromosome their DNA not in a nucleus the flagella which is used for locomotion ribosomes for protein synthesis and they're not on the outside you have the cell wall the body is rather good at rotating itself against pathogens the stomach is further acid which kills bacteria your respiratory system you'll know to track your bronchi awful of mucus and hairs which trap bacteria your skin acts as a barrier which stops things getting in and your eyes have tears which wash them out clean HIV is a virus it can be spread in a number of ways unprotected sex I'm sharing needles childbirth that's from mother to child not just general childbirth infected blood breastfeeding formerly affected mother the implications are devastating for someone although outcomes have rapidly improved recently due to the development of new drugs so HIV attacks the white blood cells white blood cells are an important parts of your immune response so if your white blood cells are being attacked and you have a little immune response the damage is widespread and HIV can develop into AIDS where you is that's acquired immune deficiency response which can lead to even the smallest infection having devastating consequences because you have no immunity against it chlamydia is a bacteria it is spread via unprotected sex it is one of the most common sexually transmitted infections in the UK about 200,000 people were tested positive for chlamydia in England each year and 70% of those are under 25 the implications are going to be pain when urinating a disgusting skanky horrible smelly discharge that is going to come from the penis the anus or the vagina bleeding in between periods or swollen testicles the damage can be long-term it can lead to infertility so the best thing to do is just wear a condom malaria is a parasite in a spread by female mosquitoes drinking your blood at night it's not quite a sexiest highlight made it out to be the implications are going to be a high fever sweats and also chills headache vomiting chest and muscle pains and diarrhea and this can be lethal in severe cases your immune system is brilliantly clever at protecting you it consumes pathogens so your white blood cells will engulf there will eat anything that they see as unfamiliar and dangerous and then it will destroy it they produce antitoxins to counteract the toxin inspector bacteria produce and they produce antibodies so that they can recognize pathogens faster I imagine most of you have been vaccinated or if you haven't at least you've heard about vaccinations vaccinations are given generally to children or people that work on holiday to different places and the childhood vaccination program in the UK has prevented millions and millions of deaths and further millions and millions of serious illnesses and in this country has wiped out a large number of debilitating diseases it is very rare develop on getting polio these days in the UK because we are all vaccinated against it at a young age the polio vaccine isn't too bad because they give it to you it on a sugar cube but it is quite painful taking your 8 week old baby to be injected by the nurse a vaccination is going to contain small amounts of dead or active pathogens this allows your immune system to develop antibodies so if you get infected with the disease at a later point your body already has antibodies to it it can recognize it it knows it's pathogen it knows how to deal with and it can be dealt with quickly before you get ill the advantages are that a large number of diseases have been wiped out for example nobody gets smallpox anymore or polio and we have herd immunity which means if a large percentage of the population are vaccinated against disease even the small percentage that decided to not be vaccinated or can't be vaccinated for medical reasons are going to be protected as well because the disease will find it very hard to spread the disadvantages is they don't always work the polio vaccine smaller vaccines are very very efficient but things like the flu vaccine doesn't always work and it can be painful and there can be side effects you may have heard about a controversy where somebody linked the MMR vaccine and autism this is completely untrue there is absolutely no link between these two because bacteria divides so quickly in a good conditions they can divide once every 20 minutes they are going to be very very susceptible to mutations in their DNA completely random changes which means completely randomly one tiny bacteria could develop the resistance to an antibiotic and it only needs one bacteria out of a large collection come resistant to the antibiotic for it's become a problem here we can see an antibiotic sensitivity test these are the discs with antibiotics on at nicosia the bacteria is growing all the way up to these days but not all the way up to this desk here so the role of antibiotics is to kill bacteria because the bacteria divide so quickly mutations can quickly develop if the course of any antibiotics any non resistant bacteria will be killed off and any resistant bacteria will survive and grow this is natural selection in action and soon only resistant bacteria will be left this is a problem because we are running out of antibiotics to treat common complications with for example and the tonsillitis and is easily treated these days small infections are easily treated these days was previously a martini thil we use antibiotics far too much they are given to animals and daily lee in feed and this is providing natural selection driving bacteria to me tight well done guys excellent work for making it this far the rest is biology only so if you're doing combined science well done you can go and have a relaxed or try some quickfire questions or go through the revision guide here we have our beautiful picture of the eye sclera which B is the white bit the retina which is where the image is focused the optic nerve which sends message to brain the ciliary muscles which change the shape of the lens the cornea which is a protective covering pupil let's light in the lens is responsible for focus and the suspensory ligaments hold the lens in place if you are short-sighted you can't see distant objects and if you're long sighted you can't see like subjects in an eye that can see correctly the lens would take the light and will focus the image on the retina it whereas someone they short-sighted the image faces before the retina and someone that is long sighted the image focuses behind the retina to correct shortsightedness we need a diverging lens and crackling sightedness we need a converging lens phototropism means something is gonna go towards the light geotropism or gravitropism means something is going to grow towards gravity meaning your reefs always gonna cake downwards and your shoes always gonna get upwards gibberellins are important for growth Ethan is important for ripening plants and auxins are important for growth nagging Odia growth in the right direction the kidneys have three functions they remove urea they control the iron content and they control the water content of the blood there are three ways we can lose water from our body in urine and sweat and when we breathe out it's important to control the level of water in the body because there is there's too much water too much water taken up by cells by as my system they might pop or there's not enough water then the enzymes the functions the reactions won't we have to take place there are three steps away that they kidneys function ultra filtration reabsorption and then the release blood enters the kidneys under high pressure and water irons UV and sugar are going to be squeezed out into the capsule which is it starts at the nephron as this all flows along the nephron useful things will be absorbed all of the sugar is going to be absorbed by active transport some ions there magnifiers that we need the ty finds that we need I can be reabsorbed by active transport and enough water that we need is going to be reabsorbed the hormone that controls how much water is going to episode is AD h which is antidiuretic hormone and then anything that isn't reabsorbed is going to come out as we its kidneys aren't working properly a person can undergo kidney dialysis the diocese machine will take over the function of the kidneys but it is very time consuming it takes about four hours and has to be done three times a week so this has a huge impact on someone's life and it's not a lot of fun an alternative to dialysis could be kidney transplants but these come with very long waiting this and there was always the risk of rejection if you want to reduce an uncontaminated culture of bacteria moving a bacteria from one place to another you first need to flame you are not relationally so that it is red hots this makes sure it kills everything that is on there you need to make sure that you open your bottles near the flame so that no further contamination can get in there open the lid as little as possible flaming the lid as you go work as quickly as possible to transfer the sample of bacteria that you've picked up in it to your uncontaminated boss and working as quickly as possible so you don't get any other bacterial contamination you can then leave the sample at 37 degrees if you've got incubator or just leave it on the bench at 25 degrees then for a few days and your bacteria will grow I've done a much longer video explaining this as you can see inside here if you want to have a look at that it's in at the playlist with all of the other required practicals when we are going to be looking at the effect of antibiotics or antiseptic on how bacteria grow we need to make sure that our work area that our hands are clean because even though these back to here are actively safeties we have to assume they're going to be pathogenic you need to make sure you've labeled the underside not the lid that agar plates and these plates will probably already be seeded for you by the technician you can put your little filter paper discs on there use forceps to do this and then incubate them on 25 degrees or 48 hours we can then we can then measure the clear zones in two different directions here please only slightly hard to see but hopefully flip close enough you can it's it's better if you measure the diameter but in this case the only thing like you do was to measure the radius because the clear zone was so large here we have our lovely little mouse who's going to be vaccinated and this is what's going to start the formation of antibodies after a while cells from the spleen of the mouse where the antibodies of form are collected we can take a known cell line a cancerous cell line blame ourselves and we can fuse them together after the antibodies and the currents of foul line have been fused together we end up with a hybrid cell these hybrid cells can be grown in culture in a laboratory and here we have lots and lots of them after they have grown up the cells can be taken and the cells and antibodies can be separated the antibodies can then be used for various different things like pregnancy tests or cancer detection pouch this is why in some videos I have explained scratches [Music]