hi guys and welcome to my all-in-one IGCSE lxl biology video 91 is much requested video is finally here I'm going to take you through hopefully every single speck point so the by tiny watch it you can feel really confident about getting that great 9 don't forget my revision guides I sell these online they are my puppet answer revision guides I understand hundreds if not thousands of hours compiling these with their perfect questions perfect answers and go check out my web site www.kpbs.org/news/evening are called mrs. grant so remember if they say give some features that all living organisms share your menacing movement respiration sensitivity you're going to say nutrition excretion reproduction and growth and that just means getting bigger so if it's nonliving like a virus you can easily say it does not move it does not respire it does not excretes which isn't list any of the missus nug factors and you'll get the marks now we're going to look at the plants and animals are very basic biology here first of all let's start by the listing the organelles that both animal and plant cells share so remember they both have star membranes cytoplasm nuclei nucleus they have ribosomes mitochondria now in terms of the plant cell there's a few actual organelles you need to list that's the cell wall the vacuole and also chloroplasts we now need to look at the role of each of those organelles and turns so because it's so key that you get these really basic questions right in your exam because if they say what does the nucleus do you need to be able to write that so what does the nucleus do it controls the activities of the South what does the cytoplasm do it's where chemical reactions take place what is the role of the cell membrane it controls what enters and leaves the south what is the wall of ribosomes and that this is new for this specification it's where protein synthesis takes place ie it's where proteins are made looking more closely at the plant cell now what is the wall of the cell wall first will stay that the cell wall is made out of cellulose and that it protects and supports the cell the vacuole remember that filled with cell sap which also helps to maintain structure of the cell lastly chloroplasts remember they're full of the green pigment called chlorophyll it gives me to the green color and that's where photosynthesis takes place a couple of tricky words you may have come across is eukaryotes and prokaryotes don't worry it's just a very posh way of describing the type of cell we're talking about eukaryotes are all animal cells as we know it and that's because they contain membrane bound organelles such as nuclei mitochondria etc so in an animal cell like I said an example of a eukaryotic cell prokaryotes we're talking about viruses and bacteria here because they contain no membrane bound organelles so they contain no nuclei which we know because they contain strands of DNA or RNA instead so we now need to take lots of different types of cell in town and know quite a lot of information about them so I'm going to start with the bacterial cell we can see from the diagraph diagram that about to yourself has a cell wall sometimes it has a slime capsule around the edge sometimes it has a flagella which is a tail that helps the bacteria to move as I've already said it doesn't have a distinct nucleus instead it has a circular chromosome which we call a nucleoid it has other small rings of genetic material we call these plasmids and that remember is important when we talk about genetic engineering then you find more typical things such as cytoplasm and sour membranes in terms of things like whether they're pathogenic or non-pathogenic remember that they can be both so pathogen is a micro organism that causes disease it makes sense therefore that some bacteria are pathogenic such examples include pneumococcus which is responsible for pneumonia tuberculosis remember that gives people TV where they cough up blood very cold blood disease however some bacteria are very useful like those used in yoghurt making the example here is lactobacillus bulgaricus we remember last Eve that bacteria are unicellular which means that they're made of one cell only looking at viruses now because that leads off quite nicely from bacteria these are very very small things are much smaller than bacteria they're far more simple because they're simply made out of protein coat which demands either DNA or RNA they don't have any typical organelles you would find in other types of cell crucial thing here as I've already said is that they're nonliving they do not excrete they do not respond grow they're always pathogenic there's no such thing as a good virus they're always out to hurt you and examples here include the flu virus the cold virus HIV which is very famous because it causes AIDS so new virus you need to know about is tobacco mosaic virus which causes discoloration in plant leaves and attitude to the fact it prevents formation next I will look here the protests this is known as the dustbin Kingdom lots of various organisms which don't fit into the other categories efficiency Pro top test some of them have animal cell properties some of them have plant cell properties starting with algae and also karela these both have chloroplasts which means they're more plant like things like amoeba are more animal light you'll see that they don't have chloroplasts they don't have a cell wall as such and they will use diffusion in order to obtain at their nutrients and get their oxygen one key one you need to know about is Plasmodium this is pathogenic because it causes the disease malaria and the Plasmodium is the small protists that lives in the female mosquitoes bodies and that's what she injects when she bites you so that's actually what gives you malaria do note that they can either be unicellular or multicellular so made up of one cell or many cells funghi now now funghi they're quite easy because you can draw a literally a plant cell but just make it slightly more circular so it has the same organelles you would find in a plant cell apartment but it obviously doesn't have chloroplasts but it does have a cell wall this is made out writing you do need to know that has a cell membrane cytoplasm it has a vacuole now there are lots of different examples of funding including nuchal and mushrooms one thing you do need to just be able to mention this is a case where you just shove in some key words and it doesn't even matter if they don't even make sense they'll give you a mark as long as you mention it they have things called high future thread-like structures which form a network called mycelium do you notice that funny carryout saprotrophic nutrition and that means that they extracellular leads secrete enzymes onto dead matter which it breaks down and then absorbs as its food crucial words here are extra styling secreting enzymes which break down dead matter and that's how they actually obtain their food there are some useful examples of fungi including yeast now remember that's used in beer and bread making why because when the yeast anaerobic respiration that means respiration without oxygen it breaks down glucose into ethanol which is currently used in beer making and also carbon dioxide and it's those bubbles that come the upside that actually help that bread to rise if we're going to use the correct nomenclature when we're talking about naming things we can talk about five kingdoms and that consists of plants animals protists bacteria and fungi one small thing to notice which could have always cut you out is how carbohydrates stored so in animals that stored as glycogen in plants that tense we store the starch things like potatoes are very starch heavy and then in funghi it's stored as glycogen also now we're going to look at organization within organisms so we're looking at key definitions the crucial thing here is to just rely on one definition and then just use it as a template for all your other definitions so I'll explain what I'm talking about right now so if we start we looking at sound now remember styles are full of organelles which I've just listed nucleus a membrane etc so what is a cell well it's a group of organelles working together to perform the same function we're going up a stepfather so we're now looking at tissue what is the tissue it's a group of cells working together to perform the same function then we're going to look at organs so what is an organ it's a group of tissues working together to perform the same function and lastly what is an organ system it's a group of organs working together to perform the same function and lastly what is the organism well it's a group of organ systems working together to perform the same function now I need to list all the various organ systems within body which have always been really bad at remembering all of them so we're going to try there's the digestive system there's the endocrine system reproductive system circulatory system respiratory system nervous system and exclusionary system but if we focus in on the digestive system for example we've the first who will take the fact that the digestive system is obviously a system so what organs make up that digestive system that organ system well it's things like the stomach esophagus pancreas small intestine large intestine then we look and look at the tissues so for example in stomach you've got glandular tissue which secretes hydrochloric acid you've got a muscular tissue which helps channel the food don't worry too much about this detail by the way I just want you to get the full picture so you're not throwing off it for questions slightly strange in the exam and then you can obviously look at the cellular level within the stomach and organelles so it's a big hierarchy me so we're now going to look at a zygote so what is this I go now remember that when the sperm and egg meet at fertilization then you're going to form one Sal that cell is called a zygote then enzyme is a biological catalyst this means that it speeds up the rate of a chemical reaction without being used up now an enzyme has a very special part on it called an active site and that's the biologically active part of the molecule and what happens is the substrate molecule binds to the active site it forms an enzyme substrate complex which then splits up to form the useful product that were after and we're going to talk now about their gesture of enzymes because I think it makes sense for us to look at the various products and substrates involved in digestion so their various enzymes you need to be aware of firstly amylase and notice that enzymes tend to end in a sec so A's amylase is made in the saliva glands in your small intestine and your pancreas and what amylase does is it catalyzes the breakdown of starch into glucose so in this case starch is the substrate is the thing entering the enzyme which is amylase and then the product here is glucose so what you can see is a very large sugar is broken down using amylase into a much smaller simpler sugar called glucose now we need to look at proteins this is more straightforward because as the name suggests it breaks down proteins so protein is the substrates and it breaks down proteins into amino acids these are the products and proteases found in your stomach in your small intestine and your pancreas the last enzyme we need to be aware of is lipase lipase breaks down lipids or fats as their more colloquial name and lipids are broken down into fatty acids and glycerol so do try remember that's the most complicated one now we need to just touch on enzyme activities so the two things you can alter is both the temperature and the pH so if you look at this graph you can see at low temperatures the enzyme activity is low the reason for this is or to do chemistry it's to do with collision theory because at low temperatures and zones have very little kinetic energy as do the substrate molecules so it means that the enzymes on the substrate aren't coming into contact very often that means they obviously can't bind at the active site and so the reaction can't be catalyzed but Alone's catalyzed as we increase the temperature you can see the enzyme activity increases that's because those molecules that come as you have them often and at those seven degrees as is the case with most animals you will find that enzyme activity has reached its peak it is at its optimum temperature the best temperature and that means the enzymes and substrates are coming together very frequently after this temperature and above this temperature we see a massive decrease in enzyme activity and that's because the enzyme has become denatured never say the word killed they're not living they can't be killed you need to say they're denatured we've all that means is that the enzymes active site has changed shape meaning that the substrate for no longer fit if we take a look at pH now you can see a very distinctive graph shape here and that's because enzymes have different optimum PHS and if the pH is either too high or too low around the optimum pH you'll find that the enzyme denatures which is why you have that cone shape because let's look at the enzyme which has an optimum pH of 7 if you go to 6.5 or 7.5 the enzyme will denature and this is true for all enzymes some enzymes prefer different pitches to other ones so proteases in the stomach for example because they're surrounded by hydrochloric acid they'll have an optimum pH of approximately three hours to hour the rest of the digestive system and find a slightly alkaline optimum pH so around 8 which is why you can't take stomach protease and put it this one tested expected to be okay now we're moving on to transport so let's first of all touch on the three types of transport so we're looking at diffusion osmosis and active transport so you need to know the definitions of these terms in great amount of detail now remember with diffusion is the net movement of particles from an area of high concentration to an area of low concentration so that's the reason why you spray perfume and one side of the room well there's a high concentration of packing particles and it moves across to the other side of the room where you can smell it that is by diffusion it is a passive process it does not require energy osmosis is very similar to diffusion however involves the movement of water which is why our definition this time is osmosis is the net movement of water from an area of high water potential to an area of low water potential across a partially permeable membrane now potential is just a really posh way of saying concentration so some one where there's lots of water to somewhere where there's little water and do you add that it's across a partially permeable membrane if there's no partial power your membrane it's not as mousses it's just diffusion so notice when water leaves the stomata from that leaf that is by diffusion customers as a whole not a part of permeable membrane lastly active transport as the name suggests is an active process this means it requires energy the reason being is because it's the net movement from an area of low concentration to an area of high concentration so against a concentration gradient let's touch on amoeba now remember amoeba is an example of a protists this is a single-celled organism which can use diffusion in order to obtain all the nutrients it needs so oxygen diffuses from outside that amoeba into the amoeba from an air of high concentrations surrounding the amoeba to low concentration inside the amoeba the reason why diffusion is appropriate is because it comes very quickly because the amoeba is single celled which means it has a large surface area to volume ratio therefore the speed of diffusion is fast enough to allow oxygen in as and when it is required but larger organisms which are multicellular have a much smaller surface area to volume ratio diffusion is not suitable it is too slow which is why they developed the need for circulatory system right we're going to be talking about all things to do with plants starting with that key plant process photosynthesis remember photosynthesis is tamid arts in the chloroplast of plant cells they contain chlorophyll which absorbs that sunlight and actually carries out the process of photosynthesis and this is the method by which green plants make their own food so let's start by looking at the word equation for photosynthesis remember that it's carbon dioxide plus water forms glucose and oxygen this is what's such a great process because of the huge volume of oxygen photosynthesis releases in terms of the balance simple equation try and learn this off by heart and remember that six is very important so you've got six co2 + 6 h2o formed c6h12o6 plus 602 now I'm torching there were lots in the practice which can act to reduce or limit the rate of photosynthesis and we call these limiting factors you need to know the definition the limiting factor it's the factor which in a reaction is in the shortest supply and a lack of this factor is the reason why rate of reaction no longer increases now in terms of photosynthesis there are three limiting factors you need to know about these are carbon dioxide light intensity and temperature so any one of these may act to limit how much photosynthesis can take place and we're going to talk about each of these in turn in a different situation so let's think about early morning we have a green plant and it's trying to go to synthesize in early morning but what could be limiting how much photosynthesis takes place well it's early morning so it's quite cold so obviously temperature is going to be a limiting factor here another limiting factor almost like the light intensity because it's not as light early morning as it isn't midday so despite complex levels increasing you will find that low light levels low temperatures limit the rate of photosynthesis the reason being is that in morning low temperatures obviously mean low kinetic energy so all those enzymes involved in those chemical reactions involved in photosynthesis can't actually come together they don't collide as frequently with their substrate molecules and that's all because of little kinetic energy if we take midday now we know that temperature will have increased we know that the light levels will increase so neither of these things will be limiting factors the most likely limiting factor in midday will be calmed outside levels and be sure that you can look at graphs on but all of these factors they make sure you understand what is going on carrying on that the plant theme we're now going to look at structure of a leaf and how it is adapted for photosynthesis let's make some generic comments at the beginning by stating that only has a large surface area which is obvious so that it can absorb more light it's thin so the gases don't have to diffuse too far looking very closing out the structure of the leaf you need to be to be able to label all those layers and discuss which each of them do and you need to be very specific here so we're going to start with the waxy cuticle the waxy cuticle is there to prevent transpiration and remember that transpiration is the loss of water on movies so a nice thick waxy cuticle prevents excess water loss next up we have the upper epidermis remember this is transparent and it allows the light to enter the leaf you don't need to say anything more than that the layer beneath this is the palisade mesophyll musical is just a fancy way of saying tissue the post a musical is what your generic plant cell looks like so it's your rectangle block it's crammed full of chloroplasts that contains lots of chloroplasts photosynthesis and this is where first since this takes place under this you have the spongy mesophyll the important thing to note here is the presence of plenty of air spaces which allow gases such as carbon dioxide and oxygen to diffuse you'll also find the Bain hair and the Bain contains the xylem and the phloem the xylem brings water into the leaf the phloem transports sugar away from the leaf then we have the lower epidermis not a lot to say here the next layer is the most important layer and that contains the guard cells and mr. Motta non-god starts control whether the stomata are open or closed and the stomata allow carbon dioxide into the leaf and oxygen and water to leave the leaf so we know photosynthesis is the method by which plants make food and they make that in the form of glucose so what do they do with that glue pairs well remember that glucose contains a carbon hydrogen oxygen so obviously contains components can be used to make other biological molecules and this includes fats and proteins so that glucose is used to make fats and proteins this used to make storage compounds such as starch which the plant can call upon in lean times and it's also used to make the sugars cellulose which is an important component of plant cell walls because it gives it its structural integrity relating to the plumbing lines luckily you don't need to know too much just learn the wall of nitrates and magnesium so the mineral ions are present in the soil around the roots of the plant and the plant obviously needs them to be healthy so it absorbs both the magnesium and nitrates by active transport so against the concentration bring it and it uses the nitrates to build proteins and it uses the magnesium to manufacture the chlorophyll found in chloroplasts you need to do some deficiency science so with magnesium clearly you will be able to manufacture clog paths or poor fill anymore so you see yellow leaves and if you've got a lack of nitrates you will see a stunted poorly grown plant so it's very short now we need to look at digestion let's first we'll discuss the definition of digestion which is that it's the great down of large insoluble molecules into small soluble ones the reason being that we need to take off food into our mouths and we need to break it down into teeny tiny pieces change its structure so that it can be absorbed through the walls of the small intestine so that's what we're on about when we're talking about digestion now I've already told you about chemical digestion which relates to enzymes entirely because that's totally altering the structure of the food molecule we need to also look at mechanical digestion which is a far more physical process that involves just chopping that food up into smaller pieces but doesn't alter the structure of that food so if we think about where mechanical digestion takes place it will be in the mouth your teeth chew there'll also be in your stomach where your muscular walls churn that food I can break up into smaller chunks so we'll start at the mouth so I've already said we've got physical digestion from the teeth chemical digestion comes from amylase which digests starch into glucose the food then passes down the food pipe which we're going to have to call the esophagus and peristalsis is a process whereby of the muscular contractions of the esophageal wall force that bonus that all of food down into your stomach here muscular contractions of the stomach lining help churn the food you've got the secretion of hydrochloric acid this has two jobs it breaks down the food and also destroys pathogens and that's the reason why you don't get sick all the time if you need some slightly dodgy food sometimes the Fugee reason is so dodgy that you still get sick but for the most part you're finally off stomach acid will destroy those pathogens remember a pathogen is a microorganism which causes disease protease is secreted that breaks down proteins into amino acids at this point their stomach empties and the food flows into the small intestine well they'll be further peristaltic contractions are don't have the exact version of the web host houses there's similar enough which forced the food along we've got more enzymes being added here lipase protease and amylase and note that they'll have a different optimum ph from the protease in the stomach they'll have a much higher optimum ph we need to mention viral now now while i was an interesting substance I think it's green it's made in the liver you must remember that it's stored in the gallbladder and it's released into the small intestine and it has two main jobs first of all file is an emulsifier and what that means is that it breaks up large fat droplets into smaller fat droplets why because it creates a much larger surface area because small droplets have a much larger surface area than large droplets and that means that lipase can work more easily on the lipid molecules on the fat molecules but if you come wallet write all that to say that it emulsifies the second law is to neutralize stomach acid it brings up the pH to an alkaline pH approximately seven or eight and what that does is it means that those enzymes that have been released into the small intestine don't get denatured by all the acidic food coming along so that's why as two main jobs to emulsify and to neutralize so at this point we've done lots of digesting our food molecules are very small they're very soluble which means they can now pass through the walls of the small intestine into the bloodstream they often ask you what the adaptations are of the small intestine lining so you're going to talk about filling primarily so remember villi are these structures shaped like this and they provide a very large surface area for absorption and that's also maximized by a presence of micro villi this video is so on detail that's making me lose my voice so yeah micro villi help increase the surface area further you've got a short diffusion distance you've got a plentiful supply of blood capillaries and you've also got presence of lacteals which are for fat absorption so the small intestine is extremely adapted for its role so once all that food has been absorbed and you just got the leftover undigestible food it passes into the large intestine and here water is reabsorbed into the blood lastly the feces because we're now at the feces stage that's the fancy word for poo the feces are stored in the rectum before they pass out of your body by the anus we call this egestion the removal of feces from the anus not to be confused with excretion you do not excrete feces you just though this crucian has a different definition it is the removal of waste products of metabolism and just to touch on a couple more definitions ingestion is the taking in a food into the body and the tab ilysm is the rate at which chemical reactions take place in the body and lastly assimilation is building up large molecules from small molecules right that was a really detailed video I hope you found it helpful moving on humans now looking advanced diets so we need to look at the various nutrients that you need for a balanced diet their roles within the body the foods that are found in and any deficiency diseases so let's have a look and start by listing these nutrients so we're looking at carbohydrates fats proteins minerals vitamins water and fiber I have listed the more societal carbohydrates foods which contain lots of carbohydrates include things like bread and rice and pasta carbohydrates an important source of energy proteins now now you find lots of protein in meat such as chicken and beef protein is important for the growth and repair of muscles now remember lots people take protein shapes to the gym why because they're trying to build their muscles at the same time so that they like to take a source of protein so try and remember it from that point of view if you have a lack of protein you get a really horrible disease called kwashiorkor people are seem very distinctive all like stomachs where your stomach comes out super far and that's the symptom of kwashiorkor fat foods which contain a lot of fat include dairy foods such as butter and cream I'm just giving you a few examples it's not exhaustive now fats are very concentrated source of energy and they provide insulation ie they help to keep you warm moving on to some specific examples of vitamins so vitamin C you find this in citrus fruits such as oranges and lemons fish Mesilla is important for the repair tissue so it helps to stick together the cells in the lining of your mouth and if you don't have an opportunity you get a disease called scurvy which was infamous in the 1500s when sailors used to go out to sea they never got enough oranges and lemons and then you see very characteristic mouth bleeds so scurvy is the deficiency disease and the way to get rid of that is by eating lots of oranges and lemons vitamin D now now vitamin D is important for strong bones you find it in fish liver oils which is gross that I hate cod liver oil but it's also manufactured by the action of the Sun on the skin so you can get a lot vitamin D sunbathing but obviously not too much don't get baths that's not a good idea either and like a vitamin D needs to rickets in children then we need to talk about vitamin A vitamin A is important for good vision in daylight lack of vitamin A leads to night blindness you find it in fish oils again live up there lots of pleasant things to be eating and also in March I mean now we're going to move onto minerals such as iron iron is found in red meats and spinach it's important for healthy blood it's a really important component of hemoglobin which is found in red blood cells lack of iron leads to anemia which is when you feel really tired and exhausted all the time and lastly calcium calcium is a mineral which is important for strong teeth and bones is found in dairy products such as milk lack of calcium will also lead to rickets last two things fiber so fiber is essential to help food move through your digestive system without 5minute you're liable to get constipation vegetables and fruit contain a lot of fiber and water water we know we need to survive without it we would die very quickly and that's because it supports all the chemical reactions that take place in our bodies now an important side note is to notice that we need a balanced diet full of all these nutrients in order to stay healthy but obviously our requirements will vary depending on our age so older people will need less food less of each of these compared with teenagers for example pregnant women they'll need more because they're supporting the growing fetus teenage girls will need more iron because the start of their periods people who exercise will need more protein to help them that the growth and repair of their muscles so it's a bit of a common-sense part of the specification but just be aware that there are differing requirements the next topic we need to tackle is respiration both aerobic and anaerobic respiration remember it's the process carried out in mitochondria which releases energy new fuel specification is the fact that ATP is produced in 11c periods is a posh way of describing the energy store that is created as a result of respiration so what is this HTTP used for well it's used in cell division it's used to build up large molecules from small molecules it's used in active transport and it's used to contract our muscles let's look at the equation for every book respiration now so you need to take oxygen into the body you need to add that to glucose an arrow and then what's produced is carbon dioxide and water and energy is released again you need the step balanced similar equation here and it's again all the 6s I hope you've noticed that photosynthesis and respiration are the same equation just reversed so in terms of the balance simple equation you're looking at c6 h-12 o-6 plus 602 arrow 6 co2 + 6 h2o + energy in a square bracket if you so wish now Arabic respiration involves the use of oxygen and that's the type of respiration that we carry out ordinarily now sometimes we have to carry our anaerobic respiration which tends to be one we've exercised and one we can't take enough oxygen into our bodies and this involves the incomplete breakdown of glucose and we find that lactate is produced instead now lactate is pretty poisonous it's what gives our muscles cramp and we need to remove that lactate so we have to take in more oxygen which we call the oxygen debt in order to break down that lactate to show the glucose is completely broken down now there are two places where anaerobic respiration takes place that you need to know about so I've already mentioned one which is in your muscles so I've given you all that information about the oxygen debt it's when you can't take enough oxygen into your body and that's because you've been doing something pretty strenuous like sprinting you also need to know about anaerobic respiration in yeast remember that yeast is a type of fungus and yeast anaerobically respires and it breaks down glucose into ethanol plus carbon dioxide and these are very useful industrial processes because remember the carbon dioxide is used to help bread rise and that the ethanol is used in beer making moving on to the breathing system so we are looking at our lungs and all the vessels releasing to that so we're going to start with our mouth it leads down to our windpipe which we're going to have to call that you hear the trachea branches to form to banquise further branching occurs which is the bonky ORS and that ends in lots of assets which we call alveoli and they're surrounded by a network of blood capillaries now if you think about it it is very much like a tree because the chakir is represented by the trunk the big branches are the wonky smaller branches of the bronchioles the alveoli are similar to the leaves so do bear that in mind now we need to talk about how there is Blanca jung-hwan fields are kept clean that's due to the presence of two types of South the goblet cell and the ciliated Sal the goblets our first of all secretes mucus that mucus is good because it traps bacterial pathogens and it stopped them from entering your lungs this is when the cilia come in because remember they have hair like projections which waft and they waft that mucus which is covered in bacteria up to your mouth work can be swallowed and destroyed by your stomach acid now what is ventilation well that's simply taking air into and out of your lungs less looking great depth now at an inhalation so a breath in so first of all the external intercostal muscles contract the ribs move up and out the diaphragm contracts and what this means is that it flattens and together all these processes increase the volume within your thorax because there's an increased volume clearly the pressure will decrease because the same run of air is now present in a larger volume and this means that I will be sucked into your lungs causing your lungs to inflate now we want to take an exhalation we want to bring out so the opposite takes place this time the internal intercostal muscles contract the ribs move down and in the diaphragm relaxes this has the effect of reducing the volume inside the thorax the pressure increases relative to the pressure outside the body and therefore our sucked out of your lungs and your lungs deflate a small thing on looking at the composition of gases in your lungs clearly air that you inhale will contain more oxygen than the air you exhale why because the whole point of reading in is to get out zoom into your lungs so it can diffuse into your blood and then be taken around your body for respiration respiration obviously produces carbon dioxide which is why when you breathe out that contains more carbon dioxide than the air you breathe in looking more closely at the alveoli because this is where gas exchange takes place where oxygen moves into the blood carbon dioxide leaves we need to look at the adaptations of alveoli for gas exchange so clearly they have a very large surface area they are thin which gives you a short diffusion distance for that oxygen and carbon dioxide to move across they are moist which helps the gases to dissolve and I can't think of anything else so that is the adaptations that are being done let's look at transport in plants so we're going to start by looking at two vessels two tissues you need to know lots about that is the xylem and the phloem make sure you can label these both inside the root at cross-section and inside the stem note that in the root that X matches with the xylem which is why the X in the middle of the root Asylum that's a nice way of remembering where as the circles around that X R the phloem inside the stamp slightly different the outer layer of tissue is the phloem the inner layer is designer try remember this because the phloem transports sugar and a feeds our little insects which bites into that stem in order to steal some food so they're biting in so that they can reach that flow and they take the food so the flow is on the outside of the staff so looking more closely at the walls as I've already told you flowing transport glucose and transports it from the leaves where it's made in photosynthesis to other parts of the plant so two growing regions such as flowers and the tops of stems and two storage regions such as the roots and that's where it's stored to start xylem transports water this time and mineral ions from the roots where it's absorbed through the new hair cells up the plant to the leaves and various places so this is an important thing for you to note as I demony transports water upwards phloem transports both up and down the plant in terms of the structures because xylem is transporting water for minerals ions it needs to be very strong and notice that it's made out of dead cells which are stacked on top of each other so there's no organized in there obstructing the flow of water there's also lignin which helps to reinforce those walls further flow has a different structure just list some key words here don't talk too much about it it has sieve plate tubes and it has companion cells and those can as containing lots of mitochondria so that they can release energy so that sugar can be actively transported in and out of the flow let's now look at transport in animals so primarily we're looking at the blood hair so we're going to start by looking at the components of blood that will be red blood cells white blood cells plasma and platelets now remember plasmid is that liquid which actually acts as a suspension it carries these various cells around the body what sorts of things are transported in class map these are going to be our products from digestion so things like glucose amino acids so soluble products they'll also be hormone as being transported they'll be urea from the liver which needs to be taken to the kidneys so it can be excreted and carbon dioxide looking more closely at our blood styles we need to look at those structure of red blood cells so we can see how they're so well adapted for that function they have a biconcave disc shape this means they're doughnut shaped and what this does is it maximizes the surface area to volume ratio ensuring that they can transport as much oxygen as possible the absence of a nucleus also means that there's more room for oxygen and due mentioning that they contain a pigment called hemoglobin remember iron is needed for hemoglobin production I mentioned that earlier in balanced diet and that hemoglobin binds to oxygen forming oxyhemoglobin next topic white blood cells and the immune system so let's first of all discuss how we prevent pathogen entry in the first place so remember our skin acts as a barrier our hydrochloric acid in our stomach helps to destroy pathogens our tears prevent pathogens entering our eyes and also your eyelashes but what happens whilst those pathogens actually enter our body and to a bloodstream clearly we can't stay ill forever and ever and ever so there are mechanisms in place which actually act to remove those pathogens the two mechanisms you need to know about are white blood cells and they are the phagocytes and the lymphocytes so starting with the phagocytes remember that they engulf or ingest pathogens by enclosing them inside a vacuole and then digestive enzymes are secreted which destroy the pathogen the second type of white blood cell is the lymphocyte the lymphocyte is far more complicated and it works by recognizing the antigen on the pathogen it secretes lots of antibodies which destroy that specific pathogen and in this way the pathogen is destroyed now it has various modes of action which helps you increase the pathogen destruction first of all it labels the pathogen making me easier for the phagocyte to recognize it and therefore engulf it in neutralizes any toxins produced by the pathogen and it also causes the bacterial cell to bust open on occasion lastly it makes the pathogen stick together with the answer relating to the lymphocytes notice that I use lots of keywords antigens antibodies for example try and include as many keywords as possible just shove them in your answer because if you look at my schemes they'll be underlined as being worth and mark each so it's worth watching them in anyway don't just keep repeating yourself you need to insert lots and lots of keywords here so we've talked all about blood now we're going to talk about circulatory systems so we need to look at the heart I've already talked a little bit about multicellular versus unicellular organisms the reason why organisms such as ourselves humans require circulatory system is because our surface area to volume ratio is too small and diffusion is too slow so we need a circulatory system which actually acts to transport oxygen around our bodies so that's the reason why we have a circulatory system the heart forms the epicenter of our circulatory system it is the pump which delivers oxygen around our bodies and you've got to know detailed information about how this actually happens so we're going to divide the heart into four do you remember that we switch over the left and right sides when we're looking at diagram why because we're picking up the heart and pushing it into our bodies so it is the opposite way around if you actually think about it so the four chambers are the left atrium right atrium they form the top two chambers left ventricle and right ventricle form the bottom two chambers now do you remember that pulmonary means relating to the lungs so if you have used the word pulmonary it means that blood must be flowing either to or from the lungs so we're going to start by picking up oxygen in the lungs it's going to be delivered to the heart to the left atrium via the pulmonary vein remember that veins bring blood to the heart arteries take it away so the pulmonary vein delivers oxygenated blood to the left atrium the left atrium contracts forcing blood into the left ventricle do you remember that the valves open here and they are the bicuspid valves they opened for our blood to flow from the atria to the ventricles the left ventricle contracts forcing blood into an artery this is the aorta it is the main artery delivering oxygenated blood around the body so that blood goes and delivers oxygen the oxygen is removed and used by respiring cells clearly the blood will now be deoxygenated and needs to return to the heart so can be pumped on further to the lungs so it's going to return to the heart via a vein the vein is the vena cava and it's going to take blood into the right atrium the right atrium contracts forcing blood through the tricuspid valves into the right ventricles the right ventricle contracts forcing blood into an artery this artery is clearly going to be flowing to the lungs so the blood can be oxygenated and this is why it it's the pulmonary artery so that's our overview of blood flow around the body let's notice a couple of things about the heart firstly that the walls of the ventricles are thicker than the walls of the HCM why because they need to pump a much higher pressure to deliver the blood much farther after all their delivery would like to face the lungs and the rest of the body or the atrium doing is pumping to deliver the blood slightly lower a couple of centimeters lower into the ventricles why is the wall of the left ventricle thicker than that of the right again it's a distance thing blood from the left ventricle is going all around the body blood from the right ventricle is simply returning to belongs your heart is here your lungs are here it's not too far why do we call this system a double circulatory system well that's because the blood passes twice into the heart for every once it travels around the body simpler organisms such as fish have a single loop so the blood just keeps passing from the gills to the heart and the body round and round and round and they're not as efficient as oxygenating their bodies as we are you've got to know quite a lot about the various vessels that travel around the body just remember that arteries carry blood away from the heart and do remember that Parma enemy means relating to the lungs and that hepatic means relating to the liver renal means relating to the kidneys so renal failure kidney failure hepatitis disease of the liver so these words if you do know what they mean it really helps because then when we're looking at what's being the vessel supplying the liver well its hepatic it's coming form at the heart which means it's an artery so it's the hepatic artery what is the name of the blood vessel and between the kidneys well it's coming from the heart so it's an artery it's going to the kidneys so it's renal so it's the renal artery the Russells leaving their organs well these are obviously got to return to the heart to become oxygenated so they're going to be veins so the vessel leaving the liver will be the hepatic vein just note the hepatic portal vein that's just the name of the vessel which shunts blood from the digestives to deliver and that's the only weight one you need to know about looking at coronary heart disease now coronary arteries coronary means relating to the heart so the heart has its own special network of vessels which supply the heart with its own supplied oxygen it can't actually obtain its oxygen needs from the blood flowing through it has to have its own special set of vessels we call these the coronary arteries and they're famous because this is how people get heart attacks they get blocked they get obstructed and it does mean that oxygen can't reach the heart muscle so part of it dies which is what a heart attack is so first of all what factors increase your chance of getting coronary heart disease so that could be a cemetery lifestyle and lack of exercise could be your diet eating diets high in fat and sugar it could be inheritance so genes some people are just more susceptible than others because of genes that they've received from their parents it could be diabetes diabetes and coronary heart disease are very closely linked stress as well people shouldn't get too stressed because that can put a strain on that heart too in terms of what happens in cranly heart disease how heart attack might occur what you find is that fatty deposits get offloaded in the walls of the coronary arteries this obstructs the blood meaning that less oxygen can reach those respiring cells because they're not receiving enough oxygen they have to analytically respire remember that producers lactate which the only poisons the muscle cells and then eventually there wasn't enough oxygen so their heart dies and their cells die let's look at how a heart rate increase is brought about during exercise for example so clearly when you exercise you're going to produce more carbon outside why because your muscles are aspiring more so that cold outside flows in the globe and it is detected by both the aorta and the carotid artery this sends impulses or messages to the brain particularly the medulla part of the brain and specifically the acceleration of now that accelerator nerve causes an increase in heart rate so the more oxygen can be delivered to your muscles and so that more calmed outside can be removed looking now at the structure of arteries veins and capillaries so let's start with the arteries they have a narrow human remember the lumen is the hole in the artery it's like the hole in a straw so it's narrow this clearly means that blood is going to be forced to it's a high pressure because it's a high pressure it means that the walls of the arteries need to be very thick to withstand as pressure being nice and detailed here and state that they have thick muscle and elastic fiber walls looking at veins now in veins blood travels at a much lower pressure this is because veins have a much wider lumen the walls therefore needs to be much thinner so they have thin muscle and elastic by the walls they contain valves and these valves prevent the backflow of blood because that blood sometimes travels so slowly it's liable to start backing up we don't want that to happen so the about forced it to move on in the right direction companies now capillaries are the tiny vessels that supply all our cells with oxygen they are once our thick and this enables a very short diffusion distance when they have an extremely narrow lumen moving on to excretion sir both implants in humans obviously when we're talking about humans will be really looking at the kidney let's start by looking at the definition of excretion it's the removal of waste products of metabolism from the body and if we look at the removal of waste products in both both synthesis and respiration implants photosynthesis obviously produces oxygen so that'll be one of the waste gases which is lost through the stomata of the plant leaf and in respiration obviously carbon dioxide is produced so that would be again in the least out of the stomata looking at excretion in humans what sort of substances are excreted first of all sweat from the skin urea from the kidneys carbon dioxide from the lungs do note that feces are not excreted they are adjusted and I really touched on this than the nutrition part of this video moving on to the coordination and response topic again starting with plants first first we'll discuss the meaning of the word homeostasis that means the maintaining of a steady internal environment so we're going to take plants first of all and we're going to look at tropisms first of all what is a stimulus and that is change in the environment so what such as stimuluses two plants need to respond to you clearly they need to respond to the amount of light and they actually also respond to gravity so we call a plant's response to light that phototropism a plant's response to gravity is known as geotropism so how do organs of a plant react to various tricks um's so let's take phototropism first of all clearly as done shows positive phototropism why because it grows towards the light roots show negative phototropism because they grow away from the light let's look at gravity now roots obviously show a positive G atrophic response because they grow down in the direction of gravity whereas stems show a negative to your trip is over because they grow away from gravity little more closely now how these changes are brought about to stand on the roots we need to understand the role of auxins so what our actions while they are plant hormones let's now explain how a plant stem may bend towards the light towards the Sun because you do see particularly sunflowers and towards the Sun that's because the auxins concentrate on the side furthest from the light source this course is self elongation on that side so the cells get longer and therefore the plants down bands towards the light they do like to show you various experiments and an important part this will be the coleoptile which of these really boring little seedlings now note that they are cereal seedlings and they are simple plants used to investigate truth isms so do be aware of how they respond if you chop their tops off if you put a microchip in between the top of the stem and the bottom of the stem if you use a by journey you do need to know different responses last see the wall of Apple in the start this is another boring piece of equipment so close that is a device used to remove any stimulus so for example it negates back to gravity or negate the effect for sunlight now we've touched on plants so now we need to look at humans and which I look like the nervous system here so let's start by looking at again what is the stimulus it is a change in the environment now that change in environment is detected by various sense organs and you need to be aware of their names and what they're actually receiving information about starting with the eye that receives light energy the ear who receives sound energy and kinetic energy the muscles in your skin receive kinetic energy your tongue receives chemical energy so your nose it also receives chemical energy why because that chemicals in food and that's what you smell and then lastly your skin receives kinetic energy and heat energy so there are two types of communication you need to be aware of the nervous communication and hormonal communication so hormones are chemicals which travel in your blood they send signals and messages to various parts of your body whereas the nervous system involves the use of electrical impulses so let's have a quick comparison between the two first of all the nervous system is much faster than the hormonal system clearly electrical impulses will get to that location much faster than hormones traveling in the blood the nervous system involves very localized responses so the electrical impulse will be locating a very specific effector muscle where is the hormonal system has far wider spread effects the nervous system responses are short-lived whereas the Mirena system involves much longer live responses and the last thing which have all you mentioned but just to read pointed out to you the nervous system involves electrical impulses whereas the hormonal system involves the use of chemical messengers so we're going to take the nervous system in greater detail now so that's first we'll look at what a stimulus is so that's the change in the environment and obviously that causes the response that the nervous system brings about do be aware of what the central nervous system is that consists of both the brain and the spinal cord let's go through all the steps involved in a regular nervous response one which does not involve a reflex action so I'm going to use picking up a book as an example so first we need to list its stimulus which is seeing or viewing the book this is picked up by receptors and these receptors will be in your eyes or proto receptors on your retina they'll send electrical impulses along your sense you know around to your central nervous system electrical impulses then pass along your motor neuron to your effector and this will be muscles or glands and if this particular case or we muscles which will contract to pick up your book remember an effect is either a muscle or gland so a muscle responds by contracting the gland responds by secreting hormones don't forget the role of the sign up so sign ups is the gap between two neurons and this is where a neurotransmitter is released to the neurotransmitter diffuses across that synaptic gap the synaptic cleft and binds to the post synaptic membrane so your electrical impulse is changed to a chemical or a neurotransmitter and then changed back to an electrical impulse at a synapse looking now at reflex actions remember these faster and they are involuntary so they do not involve a conscious part of your brain and it tends to be in response to something painful so taking putting your hand in the oven and accidentally touching one of the shelves which is hot this would trigger a reflex action so stimulus this time would be the high temperature from the oven train your receptors would be on your fingers which would receive that information about it being too hot electrical impulses would then flow again flow along your sensory nerve on to your meal a neuron this time so we're not involving the conscious part of our brains the electrical impulse passes along the most nerve onto your effector which will be a muscle in your finger which contracts to remove your hand finger away from that he saw we need to look a bit more now at the lens so I've already told you that lens the lens focuses light onto the retina it does this by a process of accommodation we can use this response as an example of a reflex action so previously I told you all the steps involved in a reflex action and we're just going to use those steps but we're going to apply them specifically to this example so I'm going to use an example which is that we have walked into a very bright room so the stimulus will be lots of light the receptor will be the rods and cones on your retina then the sensory neuron will pass along the optic nerve to the brain and there will be a relay neuron then we have a motor neuron which is also passing along the optic nerve and it will end in an effector and in this situation the effector is the muscles which you find in your iris so your circular and radial muscles and you'll find that your circular muscles will contract and your radial muscles will relax and that will act to narrow or constrict the pupil let's look at the role of the skin now so first of all the skin acts as a barrier and that actually helps prevent pathogen entry because we often have viruses and bacteria landing on us but because the skin is such an amazing intact organ it does actually prevent those microorganisms entering our body it's also waterproof which is why you don't swell up when you go swimming it forms a very tough outer layer just generally to prevent you from physical harm if you knock into something it's a sense organ for pressure touch and pain and lastly it controls our heat loss how by either sweating or the hair stand up in order to trap some insulating air close to our bodies let's now look at what happens when were too hot and too cold so we're looking further at the homeostasis topic which remember is all about controlling a steady internal environment within our bodies so let's start by looking at when we are too hot well first of all an uncomfortable have pain happens which is that we sweat the reason being that when sweat evaporates it acted to cool the body face the dilation of cars and that's the arterioles in our faith they dilate they become wider what that means is that the blood flows closer to our skin and therefore heat can be radiated more easily and also one with too hot the hairs lie down on our body on our arms and that's just so that last insulating air is trapped close to our skin because remember earth is a good insulator it keeps you warm so by making our head lower it means we cap less warm so if we're too cold clearly our hair to stand up on end so that more insulating air is trapped close to our skin and that actually acts to keep us warm we shiver the reason being that that muscle contraction releases heat energy and lastly the opposite of vasodilation occurs vasoconstriction the arterioles in our face constrict they narrow bringing blood away from the surface of our skin so less heat is radiated now looking at a separate hormone which is adrenaline remember that is the fight or flight hormone is released in bucket loads when we're under conditions of stress and it's good to imagine a really angry cats when you're thinking about the effect that an for journal and has on your body because after you imagine the cat then it will actually help you remember every single thing that happens to you when you have adrenaline coursing through your body so this cat's hairs have stood on end and that's because it wants to appear scarier to its opponent his pupils have dilated and that's to allow more light into its eyes so it can see more clearly its heart rate not that you can see this but a gentleman has caused it's heart rate and breathing rate to increase why the heart rate increases to deliver blood fast around your body your breathing rate increases to allow more oxygen into your body for respiration blood is diverted from your digestive system to your active muscles in your arms and your legs and I'll say you can either fight or run away if needs be we are now moving on to reproductions so we'll start by looking at the difference between sexual and asexual reproduction hopefully sexual reproduction is nice and straightforward it clearly you need two parents and it involves gametes remember the gametes are eggs and sperm but confuse are sex cells so the sperm and egg meet at fertilization the first are formed is known as the zygote and then it divides by mitosis to form your multicellular organism and clearly due to the production of gametes these offspring will be genetically varied which is a really important thing to note with social reproduction is that it produces genetically varied offspring so if the environment changes it means that some individuals will be better adapted if whilst others will be less well adapted and that's where natural selection comes in but we'll come across that later on in this video with asexual reproduction you only need one parent it's a much quicker process you end up with genetically identical offspring and this is why it's good when conditions are unchanging it's a great way of quickly producing large numbers of identical offspring which we call clones there is no gametes no fertilization and no zygote is formed some key definitions now so fertilization that's obviously the joining of an egg and a sperm a zygote is formed and remember undergoes a mitotic cell division so lots of my twisted state-space to form two hours for cell eight are 16 cells so if they ask you how 32 style Amira's formed sperm and egg gametes make sure you include lots of key words join at fertilization the zygote is formed it divides by mitosis to form two cells for cell eight cells 16 cells 32 styles and that's how you get lots of not so much we're not writing very much by including keywords such as gametes mitosis etc now we're looking at a sexual reproduction in plants the examples you need to know about is a strawberry runner and potato achievers so these will produce mini plants you might have seen them on spy plants as well uh produce mini plants which are clones of the original plant and you can snip them off and Transplant them somewhere else looking at sexual reproduction as obviously you need to look at the structure of a flower how sexual reproduction takes place so in order to look at reproduction in plants we obviously need to look at the structure of the flower you need to know the names of the different parts of the flower and that know that the flower is separated into both male and female parts so the male part consists of the anther and the filament so the filament is actually the thing that supports the anther whereas anthing contains the pollen grains and they're essential because they're the male gamete in a plant the stigma and the style and the ovary are the female parts of the plant the collective noun for them is the carpel and everything else is just extra detail that will actually help attract an insect or help with the wind pollination aspect of sexual reproduction in plants so now we know about a structure of the flower that will help us understand what pollination is fertilization etc etc so we're now going to look at seed formation it's important that you know every step involved in this because you could be asked a five marker on this so first of all pollen from a male anther will land on the female stigma a pollen tube will grow down the style and digestive enzymes will help break down the wall of the ovary at this point the pollen will meet the ovule which is the female gametes and fossilization takes place the ovule then goes to form the seed the of your wall forms the seed coat and lastly the ovary wall will form at the fruit so make sure you miss those last steps involved it's but first of all let's understand what we mean by the term pollination you've got to be super specific here so remember that the male gametes in a plant is pollen the female gamete is the egg for all pollination is is transferring that pollen to a separate plant so your perfect definition here is that pollen produced on the answer which is a male part of the plant it's transferred to the stigma which is the female part of the plant on a second plant and the proper definition will pop up now so you can see exactly what you need to write self pollination obviously as the name suggests that's when the plant does that itself so that's what pollen from a single plant will land on the stigma of the same plant fertilization now so remember fertilization in humans is all to do with spans and eggs fusing this time as with Mal plants it's about the pollen fusing with the egg looking at the difference between insect and wind pollinated plants so let's when we're talking about the insect pollinated one think about all the ways in which these flowers these plants make themselves appealing to insects so first of all they have bright large colorful petals these are flag light structures and they literally draw the insects attention so they're like right come and pollinate me secondly they have a nectarine the nectar is essential because that's actually why the insect is visiting the plant in the first place it's not doing the plant at favorite doesn't give a damn about the plant it's simply trying to obtain the sugar from that nectar E which is why in Seppala native plants have a nectarine they have enclosed stigma and anther and what that means is that the insect is forced to rub against the pollen or the stigma when they enter the plant to find an actually so they're more likely to pick up the pollen they have a strong scent so that the insect can smell them and that's everything I can think of looking now at a wind pollinated plant it's going to be very different from an intercept for a native plant largely because it's the wind blowing that will actually blow that pollen away to a separate plant which is why it makes sense therefore that the ant there are very exposed so that when the wind blows the pollen will literally blow off the plant and be carried by and as well they tend to be dull colored have small petals no scent for the same reason because the wind can't see these things because it's wind so there's no need to have flag like petals they'll be an absence of an actuary again because the wind doesn't need sugar they have small petals small pollen grains feathery stigma just list these all out and you'll be fine the next up we need to look at germination so first of all what is germination this is obviously what happens when you plant a seed and it effectively pops out and starts growing you need a detailed answer so first of all the seed code busts the radical is the name for the small root that appears and that starts to grow downwards a small chute will appear and obviously that starts to grow upwards and the seeds food store is used up because the plant can photosynthesize until it grows its first leaves in terms of the conditions needed for photosynthesis remember the mnemonic Wow standing for warmth oxygen and water so all these things are needed in order to enable a seed to germinate moving on to the male and female reproductive system in humans now and there's a new emphasis for you guys on the various roles of different components of the reproductive systems so let's start with the female reproductive system so starting from the beginning you've got the vagina the entrance to the uterus is the cervix and then branching off the uterus you've got the fallopian tubes or the over ducts lastly ending in the ovaries so what is the wall of the ovaries well it's to manufacture X the wall of the fallopian tube is to deliver eggs to its entrance so that's where first physician takes place uterus is obviously where the zygote embeds it develops into an embryo into a growing fetus and it supports the embryo through the placenta the cervix is simply the entrance to the uterus and the vagina is a passage leading out of the woman and it's where the penis and starts to deposit see renderings actual intercourse and lastly they give wreaths well it's not really to do with the female reproductive system but do you remember it says that put tube and it transports urine out of the body so it links to the bladder please don't think that a woman urinate out of her vagina lots of people seem to be very confused on this know there are two separate passageways moving on to the male reproductive system now so we're going to start by looking at the testes or testicles these manufacture sperm and also the hormone testosterone they link to the urethra via the sperm duct the span duct is simply achieved which transports semen from the testes to the urethra the urethra is a tube which links the sperm duct to the outside of the body and in men air transports both semen and also urine and then lastly there are some glands such as some other vehicles some of you may not need to know this the prostate gland and these just contribute fluid to the semen so that it's not just made up of sperm lastly the penis it passes urine out of the body and deposits semen inside the woman's vagina now let's be sensible last topic I'm now being sitting now we're describing the passage of sperm in the female so clearly I just said the sperm is deposited in the vagina it swims through the cervix into the uterus and lastly it swims all the way to the entrance of the oviduct or the fallopian tube where fertilization actually takes place so this one has a very long way to swim the role of the placenta remember this is a huge organ which actually supports the growing fetus so it provides the fetus with oxygen digested nutrients such as glucose and amino acids to help it to grow and it also removes waste products such as urea based on a pregnancy it takes over the role of producing the hormone and progesterone is a good place to live because we now used to look at our various hormones involved in the female reproductive system estrogen estrogen is produced by the ovaries is responsible for secondary sexual characteristics than females so those are all the changes that occur during puberty such as breasts about it meant hips widening pubic hair armpit hair all those sorts of things sexual drive develops its last and very important role is to repair the uterus lining so it causes it to thicken in preparation for a fertilized egg progesterone now progesterone is produced by firstly the corpus luteum the corpus luteum is just the left over husk effectively when the egg is ovulated it's the leftover structure that produces progesterone later on in pregnancy the placenta as I've already told you takes over the wall and its role is to maintain the thickness of that uterus lining without a thick lining a woman will miscarry because it really needs to be thick in order to support the growing fetus and then because we need to mention men testosterone its role is to support the development of secondary sexual characteristics so again the puberty changes this includes pubic hair armpit hair widening shoulders bigger muscles voice breaking or deepening sexual drive develops sperm production occurs moving on to the protein synthesis part of the specification we need to start by looking at some key definitions such as genome and that is the entire DNA belonging to an organism so we're focusing on on the nucleus of a cell remember that the role of the nucleus is to control the activities of the cell and it does this because it contains lots of genetic material so within the nucleus we know that there are chromosomes there are 46 chromosomes which is a diploid number because remember they're arranged as 23 pairs remember half the number of chromosomes is known as a haploid number however I digress I don't want to talk about that now so the chromosomes are made up of DNA you need to know the definition of a gene a gene is a section of DNA codes for particular protein we're going to talk about genetics now so we need to know the definitions of lots of very key important terms and then I'm going to show you how to do punnett squares and pedigree analysis so let's start by looking what a gene is a gene is a section of DNA which codes for a particular protein now there are different genes which control different traits so for example eye color now different forms of the same gene we call alleles so you must learn that definition so if we take I color for example different alleles for eye color could be blue or brown you must now know the meaning of the word genotype the genotype is the annuals and organism has so for example when we're talking about blue eyes it's too small bees if we're talking about brown eyes it could be Big B little B so when you ask for genotype you must provide letters the phenotype is different this is the physical appearance of a particular trait so if you're asked for the phenotype of this eye color the answer here is blue so the genotype would be little B little B the phenotype would be blue eyes so be very aware of that distinction next up we need to know the meanings of homozygous and heterozygous homo means same so it means having two of the same alleles whether that's two big bees or two little bees it doesn't matter as long as they have the same case so they both need to be apart or they're both needs to be lowercase and that is the meaning of the word homozygous heterozygous means different so that means containing different alleles so in the case of eye color that would be a big B and a little B now a dominant trait requires simply the presence of one allele for it to exhibit itself in an individual so brown is an example of a dominant trait because you can have two big bees or to a big Vienna little bee and the trait will still appear recessive requires the absence of the dominant allele so a recessive trait could be blue eyes because you need two little bees for example a blue-eyed mother and heterozygous Barnard father decide to try for children what is the probability that the children will have blue eyes so let's talk about what we have here first of all blue eyes remember blue is a recessive trait which means that her genotype must be small B small B we've been told that the father is brown-eyed which means he could be Big B small B or Big B Big B but the fact that he's heterozygous tells us that he must be Big B small B and not Big B Big B so I'll show you how to lay out your answer this is the method you should always use to start by writing mother and father at the top we know how much I love tables so you're going to write in your table between a type genotype and lastly gametes remember these are sperm and eggs so the phenotype this is the physical appearance we can see from the description that the mother has blue eyes and the father has brown eyes the genotype so these are the aliens for each parent has already written these out says small B small B Big B little B the gametes just spit these up because this is saying what the eggs and sperm will be so just write out what you vote on the genotype layer but put circles and run them to show that they're Gammy's because here the sperm and the mothers are eggs and now we need to do the punnett square so mother father who know why my iPad sometimes undoes what I've done already so she's small B small B he's big B little B let's cross them so it's big B small B Big B small B small B small B and therefore both of these will have blue eyes supposed to sneeze will have brown eyes so as a percentage likelihood its 50% will have blue eyes and 50% will have brown eyes cystic fibrosis is a recessive disease may carry mother and a carrier father decided to try for children what is the probability that their child will have cystic fibrosis so it's recessive which means to have the disease you need this genotype small C small C it doesn't matter what Leslie used to assign by the way but I'm using C here with his assistant fibrosis a carrier mother and a carrier father that automatically tells me that this is their genotype and you must learn that they're effectively heterozygous if they are carriers so worked out their genotypes so we're ready to do the genetic cross by writing mother and father at the top again you know type genotype and gametes in the table the phenotype is that they are both carriers so their genotype we know is heterozygous oh it's big C small C this means that half of her eggs will be big C half of them will be small C and the same with the sponge make sure you really show difference in the size of your letters here and now it's time to do the punnett square so this child is Big C Big C so they'll be healthy this child is big C small C so they'll be carriers but they'll still we have the same for this one and lastly this child here will have cystic fibrosis so they have a 25% chance of having a child with CF so now we need to look up had agreed diagrams and the best way to do this is by showing you an example always use this approach and do notice these are supposed to be really difficult so don't worry too much if you're planning it too much question three familial hypercholesterolemia FH is an inherited condition caused by a dominant allele that is key people at the condition have high levels of cholesterol in the blood increasing the risk of dying from blocked arteries the diagram shows the pattern of inheritance in several generations of a family with familial hypercholesterolemia so do natives with a pedigree diagram that the squares are always the men in the family you'll know this from the key the circles always represent females and in this case from the key we can see that the grey shaded boxes are sufferers of FH whilst the white boxes or circles are non sufferers so person a is heterozygous for FH use this information to complete the table so let's start by labeling the genotype of F of person a and we are going to use the letter D I mean doesn't matter what letter use but I will now use the letter D because you can easily see the difference between a capital D and a small D so labeling their genotype this is what they look like so labeling their gene type this is what they look like so big D small D so what is the question actually asking how many people have the genotype which is homozygous recessive so homozygous recessive homozygous meaning the same case recessive meaning lowercase which is why we're looking for small D small D here homozygous dominant homozygous meaning the same dominant meaning that they're both capital so that's what we're looking for now we're going to work out what the pedigree diagram tells us first of all I'm going to look at all the people without FH so all the people that are either white circles or white squares because they don't have the disease I know therefore that they are small D small D so I can just label all of their genotypes straight away and now we need to count them to work out the number of people with the genotype homozygous recessive and once I've done that I can see that it is 11 now we're getting slightly more difficult by looking for the Big D Big D so homozygous dominant so we need to infer things from the pedigree analysis first of all look at woman C so she got heard genotype from parents a and B now B is homozygous recessive which means they must have passed on a small D she has the disease which means she must have a big D so this is her genotype e has the same issue but they're a man so they're going to be Big D small D person G inherited a small lowercase allele from D they have the disease which is why they're capitalized and the same goes for person J and then looking at NOP 4 they inherited a small D from their mother they have the disease which is why they have a Big D so actually looking for people with Big D Big D the answer here is 0 person G and H have 3 children all who all of whom have FH what is the probability of G H having 3 children who all have FH this is a crazy amount of work for one mark because the only way I can see of doing this is to draw a Punnett square so we're going to do a Punnett square for G and H using my layout I already described so we're looking at the phenotype genotype and gametes from the key we can see the person G has fh H is therefore healthy from the key we've already labeled their genotypes so you can just copy that directly across and then separate these out to see the gametes now just simply do across and it's these two hair that will have fh now what is 50% as a probability where it's 0.5 and the question asked the probability of all 3 children having FH so remember when we're talking about probability we have to multiply together our probabilities pop that into your calculator and you'll get a value which is 0.125 let's look at mitosis and meiosis now so remember they're both types of cell division but they're used for making very different things so meiosis is used to make gametes so that means it's used to make sperm and egg mitosis is a completely different type of cell division you need to learn that it's used in cloning asexual reproduction and the growth and repair of cells so for example if you damaged yourself you cut yourself it will be mitotic cell division which replaces those cells if you're coming at asexual reproduction so something like a strawberry rather producing baby strawberry plants that will involve mitosis the reason being is that it creates genetically identical offspring I don't think you really need to know this but some teachers like to just chat slightly about the different stages involved in mitosis and meiosis I'm really only going to give you their names and the first stage is prophase the second stage is metaphase then anaphase and finally telophase but this is a revision video and I'm not willing to talk about it anymore at this point because I don't think it's necessary for lots of you so let's look at the differences between mitosis and meiosis I always do this as a table because it may allows me to make a direct comparison so look at the number of cell divisions first of all that will be one cell division in mitosis two cell divisions in meiosis the number of daughter cells now so that's the number of cells produced once this cell division has taken place in mitosis you're looking at two daughter cells in meiosis you're looking at four daughter cells I've already touched on the sorts of cells that I produced with just to recap mitosis produces genetically identical daughter cells meiosis produces genetically varying daughter cells which makes sense if we're using mitosis in cloning that's genetically identical for using meiosis in making gametes it makes sense that we want a sparse leg to all be different to each other and do notice that the gametes will contain a haploid number of chromosomes whereas the daughter cells produced by mitosis will contain a diploid number don't forget that haploid means containing one set of chromosomes so in humans that is 23 diploid means containing two sets of chromosomes in humans that is 46 looking at species now so what is the definition of a species well it's individuals which can be produced to produce fertile offspring and that's key it's all very well having a horse and a donkey and they made then they produce an offspring which we call a mule but the mule is sterile it cannot reproduce so that's the crucial thing about members of the same species they can be produced together to produce fertile offspring no or soggy freakazoo you're so dog is it worse out that super soggy so how is variation within a species thought about because we know the human race isn't full of billions of people that all look the same that is brought about by a combination of things first of all genetics and secondly environmental factors so two identical twins regardless of the fact they have the same genes if you move them to the opposite parts of the world it's very likely they'll have different heights different masses different slightly different skin color and that's due to the environment they experience that could be lots of Sun one of them can eat more one of them could do less exercise are you to money see you power monkey this makes a change what is the mutation it's a very random change to the genetic material of an organism very short topic now on evolution and natural selection so first through your definition for evolution it states that many organisms which are alive today and many more which are now extinct first evolved from very simple life forms that first evolved over 3.2 billion years ago so that's basically saying that innovation states that we all evolved from small life forms like bacteria which became multicellular which became more more complicated they became reptiles that became Birds and then they became mammals and then we came about so that's really what evolution is stating natural selection links very nicely with this remember this is Charles Darwin's theory now he stated and I do just want you to learn this as a five my cancer off by heart he stated that there is variation within a species due to mutation which is what I've just discussed so within a species that is variety this means that some individuals within the species are more likely to survive because they are better adapted because they're surviving they're likely to reproduce so produce offspring and those offspring will inherit those favorable genes so before you know it you have many generations that go past and they all inherited this favorable gene making them more likely to survive and I'm now going to bring up that power for answer for you natural selection can be seen pretty much everywhere on earth including bacteria so we're just going to describe how but to maybe become antibiotic resistant and it does link to natural selection so what happens is you have a colony of bacteria you give them antibiotic and due to mutations some of those bacteria are stronger they are resistant that means they are not killed by the antibiotic so what happens is all the other bacteria killed leaving behind these very strong antibiotic resistant bacteria they soon back became before you know you've got a colony of bacteria which is no longer suitable using antibiotics and that's why I'm so scared about antibiotic resistance and what it means for our future medicine ecology now not my favorite topic mainly because it's full of discussing definitions which all seem to be very similar and all sound the same so let's start by looking at definition of environment that is the total non biological components of an ecosystem so we're looking at the soil and the water for example the habitat is the place where a specific organism lives now population be very specific with your keywords here this is all the organisms belonging to a particular species which you find within an ecosystem what is the community this is the population of all species found within a particular ecosystem now what is a producer because remember producers start all food chains and food webs this is just a plant which photosynthesizers to produce its own food a Christmas humor is an animal which eats other animals or plants what is a decomposer it's an organism which decays dead material and helps to recycle nutrient to find a parasite this is organism which lives within another organism causing harm to the organism and feeding off them what is a predator it's an animal which kills and eats another animal gosh these definitions do keep coming what are biotech factors these are living factors so these are fact these are living factors which affect organisms lives so it could be other animals competing for food competing for nesting sites bringing disease and pathogens to other organisms abiotic factors are nonliving factors which affect organisms such as soil pH temperature water carbon dioxide availability number of daylight hours etc so now I've looked at all the definitions we now need to look at how we're going to solve an ecosystem so say we've got a big field and we want to know about this variety of species living there how are we going to do that and we are going to use a quadrat so remember that is a big metal frame which we're going to place randomly on the field and you're going to take a sample of the organisms you can find within it make sure you can draw a quadrat it's not a complicated diagram just through a nice metal grid and be prepared to state how you would use it so first where you need to place it randomly using a random number generator because what you do remember is you get a field you effectively market out with imaginary squares and then you use your bundle number generator to work out where to place that quadrats don't say throw it because that's really biased it means that all ping off to the left or the right so don't say throw the quadrat you're going to write down all the species you find within the quadrats and then you're simply going to repeat and place it in many other places around the field so you've got a really good feel of the place looking more closely now at pyramids and numbers impairments of biomass so remember a pyramid of numbers simply shows you the number of each organism at each trophic level so trophic level is just the stage in a food chain though for example a pyramid of numbers could start with grass the grass could be eating my rabbit so that will be the next here and lastly you'll have foxes but we don't like using pyramids and numbers because often they end up looking a really strange shape and not being pyramidal at all and that can be due to the producer only being one organism such as a tree that will be very small in comparison to the number of sparrows living on it which is why you end up with very funny shaped pyramids so we use pyramids of biomass because that actually shows the mass of living material available and therefore the oak tree for example will appear much larger and therefore the pyramid will be the correct shape why is so little energy passed from one organism to another so for example from the producer to the primary consumer so let's take grass the producer and a rabbit as an example remember the rabbit is the primary consumer the issue here is that only part of the grass is digestible much of it passes out of the rabbit as feces some of the grasses and eaten so the rabbit won't even eat the roots I don't know if that's true but it can be a reason the rabbit moves it keeps itself warm it respires it Jess I've only mentioned this it poos so these are all ways in which energy is lost within a food chain in fact the 90% is lost at each stage of the food chain if they ask you where all that energy originates from remember that is the Sun the diagram shows a food web from a habitat use information the food web so complete the table the first one has been done for you this has been drawn quite horribly so rather than looking at where the layers are you'll need you're gonna need to count the arrows and make sure you remember things about what a producer is and what a primary consumer is so starting with the number of organisms which they've done for us which one is annoying because that's the easy question just count how many different organisms there are there are eight so we do agree with them number of different types of plant you're looking for the producers here so what here is a plant where you can see from the picture even if you don't know what a cattail is but it's a cattail and marsh grass so the answer here is two the number of animals say these are the animals which form anything from the primary secondary tertiary consumer level so the animals therefore our grasshopper cricket shrew frog snake and hawk and if you count those up you'll get six number of primary consumers so remember they appear straight after the producers so we've got an arrow leading to the cricket and the grasshopper which is why the answer here is to number of food chains regardless is more difficult so food chain one will be marsh grass the grasshopper shrew hawk food chain two is the same but includes the snake before the Hawks that will be the second one food chain three is the cat tail cricket shrew Hawk food chain four will be the same but include the snake and then food chain five will include cattail cricket frog snake and Hawk so that was pretty tricky but the answer here is five the plants in this food web make the food for some of the animals to eat give the name used to describe these plants I've already mentioned that a lot that is a producer the hawk catches and eats its prey give the name used to describe the hawk in this food web so I told you earlier in my definitions that's something that catches and eat something as a predator a pesticide can be used to kill the grasshoppers in this Boutin describe the effect that killing grasshoppers would have on the number of shoes so we need to have a look oh right so the grasshoppers are eaten by the shoes so clearly if we reduce the number of grasshoppers the number of shoes will reduce because there is less food for them describe the effect that killing grasshoppers would have on the number of marsh grass plants so if we have fewer grasshoppers we can see that there won't be eating the marsh grasses much which means that the marsh grass population will increase let's do their carbon cycle now I do like this topic if you just learn it as a list of steps it's far easier than learning is the whole cycle unless you're a very artistic kind of pictorial person because I really struggle in that way but I find learning this list of steps works well every time so we're looking at how carbon is cycled in our atmosphere and within living organisms so the place I like to always start is carbon dioxide in the app so what happens to that carbon dioxide in the app well it gets absorbed by green plants in photosynthesis and it is used to make glucose those green plants then respire because they're living organisms and that releases calm dark side' back into the atmosphere so here's the first step of co2 moving in co2 moving out the plants are eaten by animals and so that carbon that was part of the plants becomes parts of part of the animal body and then the animal respires again releasing carbon dioxide into the atmosphere lastly plants and animals inevitably die and then this is why do you compose has come in they break down that dead material and they were aspire again releasing carbon dioxide so we can see cold oxide went in in the first place with green plants photosynthesizing and then it left via respiration by plants animals and microorganisms do notice that combustion which is burning of fuels and things also releases carbon dioxide into the air let's now look at human impact on the environment and we're going to start with eutrophication which is an effect what about when farmers use too much fertilizer on their land and when sewage this is disgusting washes into rivers and streams and lakes so do you remember fertilizers and sewage contain a lot of nitrates so what happens is the plants use those nitrates to build proteins and link grow extremely quickly because they're growing so quickly they end up dying the reason for this is due to lack of light basically they they block all the light for each other and they die because they can't photosynthesize my next one via death of the plants obviously provides lots of food for decomposes and microorganisms so they grow hugely a number because they're feeding on this dead material because their aerobic respires they use up all the oxygen in the water courses and this means there's no oxygen available for aquatic animals and they die and that's how leaching of nutrients of fertilizers and sewage can end up with death of all aquatic animals within water courses the greenhouse effect now where the greenhouse effect is very famous we're always talking about it because of environmental change do you remember this is due to human activity or we think it's due to human activity so burning of fossil fuels which releases carbon dioxide other greenhouse gases including methane do remember sources of methane so some of that comes from the digestion of bovine animals such as cows effectively when they fatten but that's disgusting they release lots of methane rice paddy fields the micro organisms that are found in mice paddy fields Contribution awful lot of methane to the atmosphere and remember the other two greenhouse gasses you need to know about our water vapor and nitrous oxide so there are four greenhouse gases carbon dioxide methane nitrous oxide and water vapor so what effect does this increase in greenhouse gas have on the environment what you find is that the whole of the Earth's atmosphere heats up and this leads to widespread melting to polar icecaps this means much more water is added to our seas and oceans and consequently gets the rise in sea level this floods low-lying land so Townsend City is close to the coast and it will automatically lead to loss of biodiversity because animals have less habitat less places to live in and you can see extinction of some species we also are seeing a knock-on effect with extreme weather huge storms typhoons etc this is all a result of enhanced greenhouse effect and global warming there's a change in bird migration patterns because it's getting warmer throughout the year so they're confused as to what month it is because obviously they don't know the month they just based their migration on the temperature so we see a real change in bird migration patterns we're going to touch now on CFCs remember we find these in aerosols and fridges although much less nihilist supposed to be banned the reason being is because they damage the ozone layer and the ozone layer is important because it protects us from the sun's UV rays acid rain you need to know about in GCSE chemistry remember it written AIT's because of sulfur impurities in petrol which when burnt with these sulfur dioxide into the air the high temperatures finding car engines cause the nitrogen oxygen and air to react again forming nitrogen oxides so nitric acid and sulfuric acid is produced which are components of acid rain so what factors acid rain how long the environment well first of all it damages trees then it can it should dissolve away the leaves it damages limestone buildings and lastly it gets into lakes and rivers and makes them too acidic it's quite a bitter topic is were again going to move on and now we're looking at carbon monoxide just remember that carbon monoxide is again released by car engines and it combines irreversibly with the hemoglobin found in red blood cells meaning that they can no longer transport oxygen and that's why color monoxide is such a toxic poisonous gas we need to look at the use of biological resources so this is food production starting with a look at greenhouses and how they increase crop yield remember crop yield is just about how many plants or vegetables or flowers that farm is able to grow so we use greenhouses glass houses poly tunnels etc all so that we can increase the amount of product or plant that we can grow so why does using a greenhouse increase the amount of plants we can grow because first of all you can artificially control the temperature so in the cold winter months you can add heaters and they heat up the atmosphere which increases the rate of photosynthesis more photosynthesis means more crops don't forget as well that the glass actually trapped some of the heat energy from the Sun so you end up with an enhanced greenhouse effect actually going on inside the greenhouse which again increases the temperature you can control the carbon dioxide levels water levels etc so you can make sure that none of these is the limiting factor and the water levels you can do by increasing the humidity inside the greenhouse by increasing the humidity what you're actually doing is reducing the rates of transpiration which I've already touched on earlier in this video and lastly light light is a limiting factor of photosynthesis especially in the winter when there's more dark hours that you can delete our electric lighting so the plant sterols photosynthesizing throughout the day and also the night so we're looking for maximum growth hair what effect is increase in the carbon dioxide and temperature have all crop yield Melissa's obvious increasing both of these will increase the crop yield why because increasing temperature means that the enzymes involved in photosynthesis have more kinetic energy so they catalyze reactions faster obviously don't forget that the temperature gets too hot they will be denatured so there's always a sweet spot and optimum temperature which must be used and then the carbon dioxide of course that is a reactant involved in photosynthesis so if we increase the levels of co2 then we increase the rate of photosynthesis this is a bit of a repeat of what I was talking about but it is a separate specification point which is why I'm addressing it here so how does using fertilizers increase crop yield well the addition of fertilizers to the soil replaces leached or lost nitrates and mineral ions from the soil because remember fertilizers are very rich in nitrogen nitrates and those nitrates are used by plants to build proteins what is the pesticide remember it is a chemical which kills past's so anything which feeds on plants will be counted as it passed healing press obviously reduces the damage to the crop and it also helps to increase crop yield looking at how we control pests further remember we can add chemicals to pesticides or we can use biological control which is about using other animals which kill and eat the pests we need to look at their various advantages and disadvantages so that's first of all at look at the advantages of using pesticides now these are easy to use so they're easy to apply they're effective which means they do a pretty good job of killing the pests and they're readily available issues though there's lots of issues with using pesticides firstly that they have meat very expensive that per system which means it takes a while for them to decompose so once you apply them to your soil you've got to be a well and it may hang around for many many years and the problem here is that they can often kill animals which aren't even pass which is really really bad because these are innocent animals getting killed by the pesticides because the pesticide does not discriminate correctly so what happens here is it kills other animals some of these animals get eaten by large animals so we're talking about food chains here and this is called bioaccumulation where the pesticides become stored in these animals and then as this pesticide works itself up the food here we call this by magnification and the famous case study this is DDT which was used to eradicate malaria and typhoid in the Second World War and there are still areas of the world where DDT is killing huge amounts of and fauna mutters means animals and plants another disadvantage is that you have to keep reapplying this pesticide looking at biological control NASA let's name a few examples so like I said before this is using animals to kill past the most famous well probably is using lady words because lady birds are predators to a friend's so they come along and munch on the aphids which would otherwise be destroying things like cabbages so one of the advantages of using ladybugs using biological control they tend to be quite specific and kill the pests that you're after secondly they're self-sustaining they tend to reproduce which is great because you don't have to keep reapplying lady buds intend to grow into new populations which will continue to eat the aphids and clearly they'll be non-toxic especially when compared with things like DDT however there are disadvantages they have been known to not just eat the pests that you're after you can go around eating other things so that can be both an advantage and a disadvantage they never fully eradicate the past so there will still be some aphids which survived the purge because the ladybugs don't go eat all of them when you add extra animals to an environment to an ecosystem they can have undesired effects you really know what they're going to do they can have major effects on food chains they really disrupt them so you do have to be careful before you decide to apply these animals to your ecosystem and lastly compared with using pesticides it's pretty damn slow waiting for the drugs to go and eat all the aphids whereas when pesticides you tend to find everything gets wiped out immediately quite looking at my Forgan isms involved in food production so primarily yeast so how is yeast used in bread making don't forget that yeast is a fungus when it's forced to respire anaerobically it breaks down glucose or respires glucose into carbon dioxide and ethanol that carbon dioxide is very important in bread making it creates bubbles which actually helps that bread dough to rise looking at the role of yeast in beer making so the anaerobic respiration all used to remember that produces ethanol I've just told you that an ethanol is an alcohol so that's where the alcohol found in beer originates I think there's been a change in a vs. with the new specification so with yogurt making I'm not going to talk too much about it just be aware that the bacterium lactobacillus bulgaricus is used it carries out anaerobic respiration breaking down lactose which is the sugar farming you'll get into lactic acid which gives you over that very distinctive flavor and that can be done inside a fermenter moving on to fermenters so what is a fermenter well it's a vessel which contains microorganisms which were involved in fermentation reactions so let's describe the structure of a fermenter and how it is optimized to ensure as much of the product is produced as possible so first of all we control the temperature and that's through a cooling jacket because microorganisms when they respire produce a lot of heat and the too much heat is produced and they can DNA to the enzymes and actually kill themselves so the cooling jacket has cold water flowing around it which helps to remove excess heat from the fermenter coupled with this you have temperature and pH monitors because obviously you need to determine if the temperature is too high you need to determine if the pH is too alkaline or acidic so it's capped it's important to keep watch on the fermenter we also have stirring paddles to mix up the contents and that ensures that the nutrients and heat are evenly distributed you often have an error in light not always but sometimes and that's to allow oxygen into the fermenter for any microorganisms which respire aerobically I lastly nutrients supply because obvious the microorganisms need something to respire now selective breeding so remember this is when humans use animals or plants with desired characteristics they force them to breed and then they repeat this process over many generations before you know it you have animals with desired characteristics so if we're looking at animals let's for example look at the dairy industry so dairy cows clearly a big animal here will produce a lot of milk so humans so make sure you point out that it's humans they select a dairy cow that produces a high yield of milk they make home with a ball it's quite hard to determine the bull cuz obviously they didn't produce milk but they'll make them with a ball and then her carbs are likely to produce more milk so female calves because of their high yield mother and you take those carbs and you keep repeating the process until you have lots of calves and lots of cows that produce lots of milk and you can do the same with plants so you can selectively breed plants to be a particular color so you pick flowers that are a particular color you force them to cross pollinate and then before you know you've got a load of plants with your desired characteristics such as petal color genetic engineering now this is quite a complicated topic that is chock-a-block full of key scientific words but if you like them off by heart you should be fine so remember we turn to can genetic things like insulin so insulin is a hormone produced by our pancreas and it's responsible for lowering our blood sugar levels after we've eaten and for type 1 diabetics they find that they don't produce insulin so they really struggle to maintain their blood sugar levels which is where genetic engineering comes in because in the olden days they used to obtain Pig insulin so used to chop into pigs remove the insulin and not only to have major ethical issues of this but obviously the insulin wasn't particularly fit for purpose because it came from pigs so it was important that we found a way of producing insulin from humans and so that's where genetic engineering came in and when we're talking about genetic engineering we're talking about using bacterial cells because bacterial cells contains small wings of genetic information called plasmids which we can manipulate so that you can insert the insulin gene and force the bacteria to produce lots of insulin so let's go into great detail how that is done so we obtain the bacterial cell and we cut open the plasmid using a restriction enzyme which acts as a pair of biological scissors then we use the restriction atoms are to cut the insulin gene away from the rest of the cell and we insert that insulin gene into that bacterial plasmid using a ligase enzyme and we stick it together and that's why we say how sticky ends once you've done that we're ready to put the bacterial cell into a fermenter and it's been done many many times and then I've already mentioned the fermenter and you need to provide it with the optimum conditions to the right temperature the right pH the optimum amount of oxygen and nutrients etc and before you know you're back has made huge amounts of insulin don't forget a few key words here concerning genetic engineering once that plasmid has a different gene inserted into it we call it a recombinant plasmid which means it's been be combined so it's been changed and don't forget also that the bacterial cell the plasmid is acting as a vector which means that transport biological material from one place to another so who D given the bacterial plasmid as an example and we met a different example early one in this video when I mentioned malaria the mosquito is there back to when we're talking about malarial infection because it carries the Plasmodium remember thus the throat Optus that causes malaria from one organism to another be prepared to give those lists of steps for any named human protein we can also genetically modify plants so that they can have decide characteristics this could include being frost resistant so that stops them dying when frost hits in winter it could be to extend their shelf life to stop them going off so that they have a longer shelf life and a more fit for human consumption after many days you might actually want to make plants resistant to weed killers this sounds really strange because why would you want to make a plant resistant to weed killer but think about it a farmer implies that weed killer by the way the best name for weed killer is herbicide side meaning kill herb meaning to the plants so the farmer applies the herbicide he or she wants to kill the weed however some of it will inevitably fall on the plant that they're trying to grow and obviously you don't want that to happen because it will actually kill the plant you're trying to grow so if you can make that crop plant resistant to herbicide then that's great because you applied that herbicide or weed killer it kills the weeds and your actual plant that you're after stays alive and continues to grow you can also genetically modify plants so that they can actually have health benefits then one of the most famous examples of this is Golden Rice so when poorer countries grow lots of rice unfortunately rice doesn't have a huge amount of nutritional value so what you can do is to medically modify it so that it contains vitamin A and therefore when people eat that rice I think they get a huge amount of wisdom in a in their diet and that stops them getting night blindness this is something you should remember from the balanced diet topic of the specification so golden rice is an excellent example where genetic modification has been used really well and then the most strange example of Jensen modification is when we talk about tobacco plants and these have been modified so they actually produce hepatitis antigens therefore have a potential vaccine against hepatitis so this is like crazy science but just remember that tobacco plants may be modified to produce hepatitis vaccines so we've already touched on this we've given lots of examples opportunity implants just to reiterate the advantages and to throw in a few more you can have increased salt tolerance let's now define a transgenic organism and that's where genes have been transferred from one species to another such as in goats they've had a gene from spiders insertion into them so that when they produce milk they actually produce spider webs this is crazy but it's actually true because spider web is so strong even when compared with steel if you made a spider web as large as a steel frame you would find this by the web was much stronger so that's why scientists are interested in working on artificial ways of manufacturing spider web I know you guys don't worry about this too much the point here to notice is that a transgenic organism is one that has had a gene inserted into it from another organism right I hope you found my video helpful guys these are are so difficult to make but I know you guys really like to just sit and watch the whole thing in one so you please give me a like like this video if you found it helpful it is a good incentive for me to continue my work and don't forget to stop so we're done well done for staying all this way I'm really impressed if you manage to watch the video all in one don't forget about my revision guides my purple answer vision guides are available on my website right now at www.cannainsider.com/itunes [Music] you