FULL PAPER! All Biology Paper 1 Content – GCSE (9-1) AQA Biology / Science



yeah you didn't miss read that in this video guys we're going to go through the entire content for biology paper one that does not include the required practicals but it includes everything else you need to know now we're gonna go a lightning pace so make sure that you utilize the pause feature pause things were winding when you need to but we're gonna go through absolutely everything in just over an hour and so buckle up and let's get to work okay so the objectives of this video you need to be able to answer this paper one like an absolute champ also you need to quickly highlight the areas in which you need more work and we will try in this video to solidify that knowledge if you need to go and do more work on it because obviously this is going to be rather quick then you need to be able to answer this paper like a champ so that is exactly what we're going to do and here we go okay so eukaryotes and prokaryotes right organisms can be separated into either eukaryotes or prokaryotes and it's basically based on the types of cells a eukaryotic cell has a nucleus for example we have eukaryotic cells we are eukaryotes plants are also so are fungi etc etc prokaryotic cells do not have a nucleus right all bacteria are prokaryotes so let's have a look at those cells a prokaryotic cell in particular a bacteria looks somewhat like this and so what do we have well we have a cell wall right the cell wall on the outside what does that do well it stops the cell from bursting and it provides protection to the cell we have the cell membrane right the cell membrane now you should know what a cell membrane does a cell membrane basically controls what is allowed to go in and out of the cell right then this stuff which you can't see I'm not pointing at the white circle the stuff you can't see is just the jelly-like cytoplasm which is where all of your chemical reactions occur okay this white big white thing in the middle is the genetic material right the genetic material sometimes it's called the bacterial chromosome right it's basically the DNA of the bacteria because there is no nucleus right it's just floating around the cytoplasm these things I've drawn the same color for very good reason these are plasmids right now plasmids are independent pieces of DNA which are separate from the chromosome and finally these dots are tribus ohms right and the ribosomes make proteins all right moving on you have animal cells now this is a better diagram the one I drew before obviously is a bit more amateur but almost all of the stuff here is the same to the cell membrane okay a cell membrane obviously controls what goes in and out of a cell notice the animals do not have a cell wall right the ribosome does exactly the same thing as before that makes proteins the nucleus well the nucleus controls basically what's happening in the cell because it contains the DNA right it contains the DNA before we just had the genetic material floating in the cytoplasm right that moves me nicely to the cytoplasm cytoplasm is where the chemical reactions in general happen inside the cell aside from maybe one of them which is aerobic respiration which happens in the mitochondria right individual is called a mitochondrion plural the mitochondria but that is where aerobic respiration happens and we'll look at that later on in this video so plants okay plants their cells are slightly more complex but not too much they still have the same stuff so cytoplasm okay that's where all the chemical reactions happen the ribosome they make proteins the cell wall just like in the bacteria the cell wall stops itself from bursting it provides structure to the cell cell membrane controls what's allowed to go in and out the nucleus contains a DNA poor brass right the chloroplast is where photosynthesis happens right so this is the green stuff it contains chlorophyll all right I'll just spell that out for you we're gonna look at it a bit later anyway but it contains chlorophyll okay so a chloroplast contains chlorophyll a vacuole contains cell sap right cell SAP now cell SAP is basically sugary water so contains sugars and other minerals and water and it provides structure to the cellar also obviously is a sugar storage for the cell mitochondrion or the mitochondria etc we know exactly what that does okay so that is what your cells look like but that is not what all of your cells look like we have what's called cell specialization now cell specialization is basically where we where we have cells which look different they do different things that they have different components right our cells are actually able to specialize right they need to carry out a specific function okay tissues aren't normally groups of specialized cells which all carry out the same function right and we're gonna have a look at a few examples of specialized cells boom so first we have the sperm cell right which is this one at the top left the sperm cell clearly doesn't look like what the most or what the generic animal cell looks like now the sperm cell is a nucleus up here in its head and actually contains half the DNA right a sperm and an egg cell contain half the amount of DNA of the rest of our cells obviously because they need to join together and then that makes a full organism now they have a load of mitochondria in their body and then they have this tail right now the tail is so that the sperm can't swim because of the sperm it needs to make its way to an egg in order to fertilize it now moving actually requires energy the mitochondria is there so that it can carry out aerobic respiration and provide that energy so that is why this sperm cell is shaped exactly like it is so root hair cell is the next one root hair cell now I'm sorry for my my bad writing I'm going to try and make that a little bit better for the rest of the video but a root hair cell now the job of a root hair cell is to absorb water and to absorb minerals right we're gonna have a look at this in more detail again in a little bit but it has this protrusion right this protrusion or the roots hair is as it's actually called now this actually gives it a high surface area to volume ratio right and having a high surface area actually allows diffusion to happen faster it allows us most just happened faster it allows basically things to be absorbed by that cell more quickly and then it can pass it on to something else then finally we have a neuron right this top right is a neuron which is basically a nerve cell now this is a very interesting cell what it actually does is it sends electrical impulses right from the cell body away and so electrical impulses are allowed to go down here right these things are called myelin sheaths myelin and I just said I was going to make my writing better and this is like even worse so I'm gonna try from now on this is called a myelin sheath now a myelin sheath provides insulation and therefore it allows electricity to be conducted and more quickly it's like the outside insulation on an actual electrical wire that's kind of a way you can think about it then here right so all of these all of these and all of these right you can think of these as basically nerve endings okay these actually join with other neurons okay because the electrical impulse needs to be passed from one of these cells to another one so that we can coordinate all the information it can get to our brain it can go back out of our brain to tell us what to do etc etc by the way this long part here yeah so all the way is called an axon right so the electrical impulse travels down the axon and that is how it actually works okay now some important information about specialized cells is that once a cell becomes specialized it's not actually then able to differentiate into another type of cell differentiation or cell differentiation is the term we use to refer to a cell becoming specialized right now plants actually retain unspecialized cells in a tissue called the meristem okay now these can then grow into any type of cell once a cell has specialized it can't then turn into another type of cell but an unspecialized cell can and so plants are able to do that that's why we can actually cut off a bit of a plant planted in the ground and actually grow a whole new plan you certainly can't do that with a human wouldn't make sense to cut off part of your leg put it in the ground and then grow another human obviously that doesn't make any sense whatsoever okay so microscopes there are two types of microscopes if you are broadly speaking those are electron microscopes and light microscopes okay an electron microscope actually has a higher resolution and a higher magnification than a lights microscope right just so you know magnification means basically how far you can zoom in resolution is actually the distance between two points or the shortest distance between two points of which you can tell the difference so for example if you can zoom in to an image but it's really really blurry and you can't actually see the difference between one point and the other and that's a lower resolution if you increase the resolution then you can actually tell the difference a good example of this in real life by the way is something like a TV or a phone screen or whatever right the higher resolution means that there's more pixels which means you can obviously tell the difference between one dot and the next one and it makes it less blurry but anyway moving on we have our light microscope and you need to know this basic structure so the eyepiece lens right this does magnify but this is where you actually look right you've then got here the objective lenses right and the objective lenses you can you can switch those and they also magnify so you've actually got to two parts which magnify yeah and the overall magnification is actually the magnification of the eyepiece lens multiplied by the magnification of the objective lens all right you've then got two focusing dials the course focus right that moves things quickly so that you can quickly move things kind of into focus and then the fine focus allows you to tweak it a little bit and try and get it exactly as you want what they actually do is they move the stage up and down right in the stage is basically this is where what you're looking at actually rests let me rub those out now what you actually have here is a specimen now the specimen is what you're actually looking at right and the specimen is basically under or between what we call a glass slide right and so that piece of glass is actually a slide the specimen is what you're actually looking at right the stage is where it's sitting underneath you have a mirror and that mirror reflects lights up through the through the sample through the specimen through your eyepieces so you can actually see now sometimes you don't have a mirror there sometimes you have an actual light source instead which is better okay and this is the equation that I mentioned before magnification of the eyepiece lens times by magnification of the objective lens gives you the total magnification for example a lot of time the eyepiece might be a times 10 I piece okay and your objective lens where you have all different types you might have a times 100 or you might have a times humor over times 200 etc your overall magnification will be those two multiplied yeah so 10 times 100 equals 1000 that would be your total magnification if you were using of those two lenses okay now another way in which you can work out magnification which is the more common thing you're going to be asked is if you have the image size and you have the accuracies so let's say they gave you a diagram of a cell and they told you how big that cell is in real life now what you what you would do is you and have a look at the size of the cell let's say that they told you the cell was no point not one millimeters or that's the same as 10 micrometers right then you measured the image and it was like two point four centimeters right now I'm gonna write it in millimeters because those units have to be the same so two point four centimeters is 24 millimeters right now if I was using my actual my equation sorry I would take my image size which is 24 millimeters divided by the actual size so the actual size of the cell which is naught point naught 1 millimeters right because they're both in millimeters that means that the units cancel out and we get our magnification and your magnification in this case would be 2400 right now so it's 2400 times magnification in that example all right so moving on we mentioned electron microscopes now electron microscopes clearly look different they are a bit more complicated and they're a lot more expensive and they can give you a higher resolution a higher magnification and they only give you black or white images on black and whites or and black always black and white images okay now there's two types and those are the scanning electron microscope and the transmission electron microscope right a scanning electron microscope is one in which a beam of electrons is used to scan across an entire sample or an entire image okay but not at the same time and then those images are put together to give you an overall image now that can give you a 3d image on the other hand a transmission electron microscope actually fires electrons through the sample in one direction and you end up with a flat to the image just like you would normally get from a light microscope except it's going to be way more tell because you have such a higher resolution all right so now let's talk about your DNA or just DNA in general so DNA is organized into chromosomes each body cell has chromosomes in pairs right which means that your cells are diploid cells with the exception of the gametes which are the sperm and the egg and those have half the amount of DNA and so we call those haploid cells okay so this is basically the hierarchy of your DNA right your DNA kind of has this structure right on the right hand side and then if you add loads of those together in a big big long chain or long polymer then you get to what we call a gene and these genes are organized on two chromosomes which is what you see on the left hand side now a gene a gene is a piece of DNA which basically codes for characteristic and there are loads genes on a chromosome right and this on the right hand side is just an image showing you an actual real-life representation of your chromosomes okay so genes are sections of DNA which code for characteristics they actually code for proteins right and those proteins give you characteristics each version of a gene though is called an allele right so you could have the hair color gene but you have the blonde hair allele or the brown hair allele right and so that's the difference – okay so the cell cycle now cells are constantly dying and in the process of being remade right cells just don't exist you for your whole life you're always replacing yourselves and different cells are replaced at different rates mitosis is the type of cell division with which we replace ourselves right so if we need to replace our cells they divide by mitosis now that is one part of the cell cycle and cell cycle has three parts in broad so the first part is called interphase now most of your cells are in interphase right interphase is the normal functioning life of a cell but while it is in interphase it is growing and it's increasing the number of mitochondria and ribosomes and other things inside the cell so that it's ready to divide right then during mitosis the cell does divide and it produces two identical cells right but then they need to split apart from each other and that splitting apart is called cytokinesis and then you end up with two separate cells right so let's look so you start off with a normal cell right what you do is you double the amount of DNA and then those and then those chromosomes actually pair up okay they pair up and you can see in blue and that you have those chromosomes now in pairs okay so the nucleus disappears during mitosis after this has happened and those chromosomes which have now been copied and paired they actually line up in the middle of the cell right they line up in the center of the cell as you can see here in the third diagram and then what we have are these fibers right those black things so these right I'm just gonna rub that out are actually called spindle fibers right they join to each individual pair of chromosomes and then they pull apart and they separate the two copies of chromosomes to either end of the cell and so that's what you get here and that's what you get here right then the cell begins to divide because if you think into either end of the cell you now have a full amount of DNA that you had in the original cell and so you separate those two either side and then the cell starts to divide then cytokinesis occurs right which is this stage when you go from here and you actually split apart that's actually part three in the cell cycle which is cytokinesis so interphase happens before this this is mitosis but this last part here is actually cytokinesis okay stem cells so stem cells are undifferentiated they can differentiate into specialized cells we've spoke about those already embryonic stem cells and animals can differentiate into anything right they're what we call totipotent okay adult stem cells which we all also have in our bone marrow for example they can only differentiate into certain types of cells and so they're not called totipotent they're called pluripotent right adult stem cells like in your bone marrow can differentiate into blood cells right they can form red blood cells they can form white blood cells but they can't form things like nerve cells or muscle cells right so that means they're not as good if you like plant cells though contain totipotent stem cells in a tissue called the meristem we spoke about that already that's how plants are different animals that's why we can clone plants simply by cutting pass them off right so stem cells could provide cures are various different conditions because they provide the opportunity for us to actually grow new cells right new cells and therefore new tissues for example if you were a major burns victim you could grow a load of your skin tissue to cover it up and then skin graft it and then it's your own skin growing from your own stem cells etc etc okay we could we can actually replace whole organs etc and so that's very interesting but we could also use them to genetically engineer a human being and change their DNA and obviously there are ethical issues behind that right people get really really upset about this kind of thing and so you have to be careful when you're answering questions you need to add up both sides right well there's there's clearly potential benefits from it but there's a chance it can be abused also where do you get the embryonic stem cells from if you're taking stem cells for an embryo then you're probably killing the embryo and some people argue that those embryos are already living things living people and therefore you're actually killing people and so some people actually see it as murder and so there's massive ethical issues behind it okay moving on transport transport is just the movement of stuff you have three types of transport you need to know which diffusion osmosis and active transport diffusion is the net movement of particles in a fluid right that just means not a solid so it could be a liquid or a gas from a higher concentration to a low concentration down its concentration gradient and this is an example right this is in the lungs right so in the lungs this actually happens now these are alveoli right so this is your alveoli now the line okay and this here is our blood all right so our blood it's our blood vessels now when we breathe in we get oxygen into our lungs into the alveoli and then oxygen diffuses down its concentration gradient because high concentration here low concentration here into the blood and that's exactly where we want it right on the other hand we've got a load of co2 in the blood and not in the alveoli in certain diffuses the other way and then when we breathe out then we get rid of that carbon dioxide and then the process continues okay osmosis osmosis is kind of like diffusion but it only includes water and so it's from a high concentration of water to a low concentration of water and it must be across a partially permeable membrane right that's so important has to be across a partially permeable membrane now what a partially permeable membrane actually means is just a membrane which lets some things through and doesn't let other things through okay so for example it lets water through but doesn't let like large proteins through it which which a lot membranes done okay so what would actually happen in osmosis well it depends on the concentration of water in your two solutions now – just to be frank if you have pure water then that's the highest concentration of water that you can get and as soon as you start dissolving other things in water its concentration goes down so the more things you have dissolved in water the lower the water concentration okay and water will follow its concentration gradient so what you have here is three scenarios so we have a cell and this round the cell is the membrane which is a partially permeable membrane cool and then outside it we have another solution right so we have two solutions the inside are selling the outside a cell in a scenario a we say that both solutions are hyper sorry are isotonic isotonic means that they have the same water concentration and if they do have the same water concentration then the net movement is going to be zero because the concentration is already the same be this the outside solution is known as hypotonic right hypotonic means it has a higher water concentration so water moves from a hypotonic solution into the other solution okay and so it moves down its concentration gradient on the other hand right by the way the dot the blue dots obviously a water and in C it's the other way around you have a hypertonic solution which means a concentration of water outside the sullen in C is actually lower than the water concentration inside the cell right and therefore water moves from the cell and the cell shrinks and this is actually the basis for one of your required practical is the one with the potatoes which we'll look at in a separate video okay active transport so movement of particles from a lower concentration to a higher concentration which requires energy right that part is so important this does not happen naturally osmosis and diffusion happens spontaneously naturally you don't do anything active transport does not active transport one example of active transport is using the route hair cell which is a type of cell we've already seen they carry an active transport to bring in even more solutes even though the cell maybe has more solutes than the outside does already right so the point is that the plant wants as many salts as possible it might be magnesium my potassium might be nitrates etc and if they already have a load they still want more and so they bring in the extra using energy right however news energy is important right it actually does use energy in order to do this it doesn't just happen naturally and so they need to carry out respiration in order to provide the energy okay deep breath next topic coming straight up and so organization levels in living things you need to know that this hierarchy of organization see the smallest basic unit of an organism is the cell cells or similar cells are grouped together in tissues to carry out a function those tissues are then grouped together into organs to carry out an overall function right and then organs are grouped together in organ systems to carry out a broad living function and in organ systems are grouped together and that forms your overall organism which is actually the thing right for example we are organisms okay so one example of an organ system is our digestive system the purpose of it is that we need to absorb nutrients from our food right this allows us to break down large insoluble bits of food into small soluble molecules which we can actually dissolve absorb and then actually use okay so small molecules can actually diffuse into the blood and be transported where they're needed but the large insoluble molecules actually cannot and so here is our digestive system let's talk through the individual parts and their functions now so first of all the saliva glands what do they do well they make saliva that seems blatantly obvious but what's the point in saliva right saliva actually acts as a lubricant right as a lubricant okay so it allows us to swallow things etc etc and also it contains amylase right amylase which is an enzyme which breaks down carbohydrates right so an enzyme which breaks down carbohydrates that's why if you put something that's a carbohydrate into your mouth it'll eventually break down and dissolve in your mouth it's something like a piece of steak which is made of a load of protein actually won't alright you then have your esophagus basically that just connects your mouth to your stomach and so the esophagus that's pretty much his only job the saliva helps things travel down the esophagus and reach the stomach in that and the stomach is where a lot the good stuff happens so the stomach basically turns your food rights there are muscles in the wall of the stomach which churn your food and break it down into smaller and smaller pieces which allows us to digest it now the stomach also contains pepsin right pepsin which is a protease so breaks down proteins so actually your food is beginning to be digested in the stomach as well right it also contains stomach acid right stomach acid and that's cause pepsin is an interesting enzyme it works best at pH 2 or 2.5 right most enzymes work best at pH 7 we're gonna have a look at this in a bit more detail in just a little bit but the stomach acid has another job also if you swallow pathogens right if you swallow things which give you disease or whatever they actually get killed in in the stomach because of the stomach acid and so that is great all right what about the liver well the liver actually produces bile right it produces bile and bile is really important because the stomach acid would actually damage any other organ in your body and so bile neutralizes the stomach acid to make it okay again right it returns the pH to an okay amount what bile also does is it emulsifies fats which just means it allows us to dissolve fats and therefore absorb them as we move on into the small intestine the gallbladder by the way is just where bile is stored so you make it in the liver and you store it in the gallbladder ok the pancreas okay the pancreas actually produces protease right protease is a is a broad category of enzymes which break down protein carbohydrate is carbohydrates which actually break down carbohydrates and lipases which break it down lipids which are fats and oils now these enzymes are actually produced in the pancreas but then they are sent off into the small intestine because they actually work in the small intestine not in the pancreas the pancreas is job is actually just to produce them right so the small intestine that's where a lot the good stuff happens small intestine is actually not very small it's actually the longest part of the whole digestive system right it's really long but the job of small intestine is to absorb all of this good stuff that we've been breaking down into the blood alright so the small intestine is where you absorb all your nutrients and stuff into the blood and notice on this diagram we've got these things called villi which is actually the lining of the small intestine right the small and small intestine is actually lined with all these stuff right the walls are not smooth they look like this that is to massively increase the surface area which massively increases the rate fusion now that is extremely important because it means that we can absorb things from our food before they end up being released perfect and then once that has happened right so you've absorbed things like amino acids glucose and stuff like that and fatty acids and whatever from your fats then everything that hasn't been digested basically goes into the large intestine and the large intestine is basically where your your insoluble stuff like like fiber okay is and you absorb water from it and then one once that's all done then the last of your food gets to your anus and then you know what happens after that you get rid of it and that's called defecation alright so we mentioned digestive enzymes let's have a look at them in a tiny bit more detail you've got carbohydrates which which breaks down carbohydrates into sugars and Malaysia is an example protease is break down proteins into amino acids pepsin is an example and stomach lipase is break down lipids into fatty acids and glycerol you don't need to know an example of those so how do enzymes actually work now an enzyme is this blue thing right which is just a big protein and it's got this part here which is called the active site right the active site is basically where something fits into it the job of an enzyme is just to speed up a chemical reaction right that's all it does is called a biological catalyst but what really happens is what what's known as the lock and key hypothesis right you have something which just fits into that enzyme and therefore it allows the enzyme to work on it and then the reaction can happen right so for example in a digestion if you have a carbohydrate then a carbohydrate is that orange thing which just fits into the blue thing which is the enzyme and then it's able to be broken down and you see on the right-hand side you now have your products after they have been broken down now problem occurs if you either have a temperature that's too high or a pH which is too different to the pH that the enzyme likes enzymes have specific temperatures which they'd like to work out enzymes have specific ph's which they like to work at and you can see here that if the temperature or the pH changes too much then the enzyme changes shape right this is called denatured right this enzyme has been denatured right it doesn't mean the enzyme is dead but means it won't work anymore enzymes can't be dead because they're not alive in the first place right but it won't work anymore because it's irreversibly change shape and notice that this molecule now cannot fit in it and that is that okay so let's have a look in more detail temperature most enzymes have an optimum temperature of around 37 degrees that's why our body temperature is 37 degrees they can't go too much higher right so this is actual activity of the enzyme or its rate of enzyme reaction okay you can see it's got an exponential curve as it increases because rate of reaction just increases as temperature goes up but then if you go too high then this happens and you get your enzyme denaturing and then it plummets and you get no reaction at all right like 50 degrees or whatever that's why our body temperatures reaches 50 degrees we are guaranteed dead okay so pH pH is different pH it's not just that the enzyme sorry if I go back just quickly notice that the reaction is not zero at zero degrees that's because even if you freeze the enzyme it doesn't mean it's denatured it just means the rate of reaction is really slow okay if you freeze it it is not denatured if you go too high it has denatured so back to pH if your pH goes too high or too low both will denature your enzyme and and therefore it's broken and the rate of reaction just just goes to zero okay and so that is the graph that looks like if we had something like pepsin by the way which has a lot some pH of around about 2.5 the graph would look exactly the same I say exactly the same look I can't draw but but in a different place right so that's basically it's you have enzymes which work best at different temperatures just most of them a pH so okay so the heart moving on the job of the heart is to pump blood to our lungs to be oxygenated and then pumped that oxygenated blood to the rest of the body we have a double circulatory system whereas fish and insects every single circulatory system so let's take a look at the structure of the heart and now so this is the heart it's actually the reverse orientation so what you see is the left is actually the right is as if you're looking to someone looking at someone sore who's facing you so this here is the right side and this here is the left side right so what you have is four chambers in the heart the top two are called the atria singular atrium and the bottom two are called the ventral ventricles sorry yeah and so first blood in to the right atrium right the job of the atria is to take blood in right then they contract and pump blood through to the ventricles so blood comes into the right atrium from the body right from not from the lungs from the rest of the body so it's deoxygenated but comes in here then it gets pumped into the ventricle right the right ventricle and then the right ventricle pumps blood to the lungs via a blood vessel called the pulmonary artery now any vessel that leaves the heart is called an artery any vessel that comes back to the heart is called a vein right so the poor moan or he just means the lungs so it's pumped via the pulmonary artery right that actually goes to the lungs and gets its oxygen and does whatever it needs to do then it comes back via the pulmonary vein so the pulmonary vein brings blood into the left atrium that pumps into the left ventricle okay and then that pumps via the aorta which is this one it's the rest of the body okay so it comes into the right atrium it's a deoxygenated blood let's just rub this out the oxygenated comes into the right atrium pump to the right ventricle then pump to the lungs then it comes back into the left atrium gets pumped to the left ventricle then gets pumped to the rest of the body and then it happens again the reason it's called a double circulatory system is because it enters the heart twice in one cycle so if you want to have a quick go look at this diagram which has no labels pause the video and have a go at labeling it but in the interest of time I'm gonna move straight on with blood vessels so there are three types of blood vessels arteries veins and capillaries the arteries carry blood under high pressure away from the heart the capillaries which follow from the arteries carry blood to the tissues into all your cells and they actually are what is involved with the exchange of things like oxygen and whatever and so they are really small and they go around all of your tissues then finally the blood it ends up in the veins and they're kind of the motor way that brings blood back to the heart so that can repeat the process and so here we go on the left hand side you have an artery you see it's got these thick walls right the really thick walls it's got muscle in them as well and the lumen is actually quite thin right there are no valves in the answer is either because this under high pressure doesn't need them and because it's under high pressure that's why it needs those thick walls so that they don't actually burst right they lead into the capillaries the capillaries are really small they actually one cell thick their walls and so that allows them to quickly allow things to diffuse in and out which is exactly what they need to do because they're exchanging stuff with other cells and then finally the blood leaks into the the veins and then the veins take it back to the heart by the way the veins the reason they've got thinner walls and a larger lumen is because it's under a lower pressure right it's not being pumped into the veins it's being pumped into the arteries and so it's a lower pressure they need valves to stop the blood from going back on itself right in those valves allow the blood to go in one direction back to the heart and everything to be okay okay so what is your blood actually made of it's more than just the red blood cells it actually also contains platelets white blood cells and plasma the red blood cells are actually what makes your blood red right they look like this so on your right hand side you can see red blood cells okay they've got this flat biconcave disc shape which gives them a high surface area that's great because it allows them to transfer oxygen right that's actually their only job they contain a load of hemoglobin yeah and that hemoglobin actually carries oxygen yeah they actually don't contain a nucleus they don't contain mitochondria because those things would just take up space instead they just packed to the brim with hemoglobin which allows it to carry a load of oxygen okay platelets are actually small fragments of red blood cells right they're small fragments you can see them on the bottom right and they act as like a mesh to stop you from bleeding they all clogged together and form this mesh stops you from bleeding and they get joined together by a protein called fibrin which is great the white blood cells they're involved in your immune system we're gonna have a look at those in a little bit but phagocytes and lymphocytes are two examples blood plasma is actually the liquid part of your blood and it's the part one forgets your blood is a liquid right those red blood cells are not the only part of your blood actually the majority of it is plasma which is yellow in color right it's only red because we have the red blood cells if you separate them you do get the plasma which is yellow it's got a load of water in it this is where things like sugar dissolves writes your blood glucose concentration is actually because it's dissolved in the plasma all right and so finally on the heart we have heart disease and coronary heart disease is one example of that so I'll put it in brackets color coronary arteries of the arteries which actually take blood to the heart muscle right not going into the heart into the into the chambers but actually supplied the heart with oxygen and if they get clogged up then your hearts could lack oxygen and lack energy and therefore it could stop working such a severe problem that's what causes heart attacks right and one of the main reasons is they get clogged up with fat like this right it looks all gooey and disgusting but this is actually what happens if you get a lot of fat deposits in your arteries and this is actually called atherosclerosis right so after oh and I'm gonna have to write fairly neatly Sclerosis okay that is when you have fat deposits in your arteries and that can actually lead to a really high blood pressure can lead to vessels bursting can lead to heart attack etc etc we can actually try and heal those by using these things which are metal cages good stents right those stents open up the artery which is great so what else what we can also replace faulty valves if you have a faulty valve it can cause blood to mix where it's not meant to mix and that can end up with you not having a high enough blood pressure it can end up with you not having blood pumps around the body properly and so we can replace those with either other valves from other animals or from other humans who have died or we can actually make our own out of carbon fiber and and we can use those finally if your your heart which is able to produce its own electrical impulses it actually causes itself to beat right on its own if you're if that's the part of the heart that does that so you're a natural pacemaker breaks you can use a man-made pacemaker which is what you can see here that actually supplies your heart with electrical impulses which allow it to beat as it should all right moving on we have non communicable diseases now coronary heart disease is a non communicable disease but we have other ones as well those are ones which cannot be transferred from one person to another especially by a organism okay so a beastie is another example of that right poor diet and exercise is the general cause obesity coronary heart disease as we just saw is an example now there are several risk factors for a non communal communicable even disease and those are things like alcohol those are things like smoke those are things like eating really fatty sugary foods and ignoring eating your five a day the opposite to that is eating a really healthy balanced diet and getting regular exercise those drastically decrease your risk of non-communicable disease and so that is something really important to remember however one example of a non communicable disease is cancer right not very happy topic but you do need to know about it so cancer is a result of changes in cells which causes them to uncontrollably divide that causes a tumor now a tumor can either be malignant and animal ignant tumors the bad one or the really bad one where it grows out of control and spreads from one part the body to the other in order to treat that kind of cancer you need to find it and stop it really early right it is doable but it's something that is difficult you need to find it and and treat it early on if you're late in in that stage then it's very very difficult to treat a benign tumor right so a benign tumor is actually normally contained within a membrane which means it can't spread out of its particular location those ones are generally less serious but they can still be serious for example if you have a benign tuna in the tumor so a tuna in the brain then that obviously causes problems and so here is just a diagram showing you these cells here are forming a tumor right there just multiplying and multiplying and eventually you're gonna get more of them or more of them and more of them bla bla bla the cells around it on normal cells but you can see they're getting outgrown out competed by those cancer cells which is not a good thing so what causes cancer we just said that mutations in DNA or changes in in your cells which hint is a mutation in your DNA causes it so it's actually caused by a mutation in DNA leading to that uncontrolled cell division more than 20% of cancer has been linked with smoking and/or alcohol consumption right now it's quite a startling percentage but when I say linked it doesn't mean they have definitely definitely caused it but it's like war they've probably caused it yeah because mutation can just happen randomly you can have someone who is the healthiest left in the world never smokes never drinks and still gets it which is annoying right but the chances are just lower other things ionizing radiation can cause mutation right if you if you're near something that's radioactive then that can actively cause mutation which can lead to cancer genetic factors can cause mutation right if you've got a certain gene the B's the BRCA gene is a very common example for breast cancer and also being infected with something like the HPV virus or hepatitis B virus those can increase your chance of cancer as well okay so how do we treat cancer what we use chemotherapy right chemotherapy means using chemicals and you use them to actually kill the cancerous cells and we use radiotherapy and that means using radioactivity in order to kill those cells the problem with these are that they are not cancer specific they will actually kill any cells and so if you target them to the cancer cells you may also be killing and you normally are also killing healthy cells as well and so that can do damage and depending on where the cancer is you might want to be more careful so if it's in the brain then you've got to be extremely careful right healthy lifestyle is a great way of treating it is actually a great way of avoiding it but also stopping it from growing faster and faster right so make sure you live that healthy lifestyle finally antibodies right antibodies are a very interesting more recent treatment for cancer and that's something we're gonna have a look at a little bit later on but not yet okay so moving on to plant tissues so plant tissues right we just spoke about animal tissue plant tissues we're going to be a bit quicker with here you have a cross section of a leaf right this is like looking at a leaf sideways and you've got all these different layers of different cells which are actually grouped into tissues so you've got the waxy cuticle which is right this bit at the top which provides basically protection to the leaf it's not water it doesn't let water in right it's waterproof and so that's why you see water dropping off the top of the wefts cuticle it doesn't really let water out either which is a great thing the upper epidermis which is basically a protective layer as well not really much happening there palisade mesophyll right knees are fill basically you can think of that as where the good stuff happens where photosynthesis happens the palisade is the main one right you see these are big cells which are all bunched together and so there's loads of chloroplasts and you've got loads of good stuff happening there spongy mesophyll right those are towards the bottom they still carry out a lot of folks in this as well but they've got holes in between and that's why they're called spongy mesophyll there's a reason for those holes being there it's so that oxygen and carbon dioxide can be exchanged and let out without going into another cell finally you've got the stomata down the bottom right those are actually holes right so each each one is called a stoma overall they're called stomata if there's more than one those are holes which which the plant can open and close around them right I didn't write this year around the Moser called guard cells where I actually write that guard cells guard cells and what they do is they actually open and close the stomata right that's their job okay so xylem and phloem and so if we have a look on the left-hand side here first you have the phloem now phloem is responsible for moving food basically glucose and sucrose around the plants right it's basically made up of cells which are interconnected right and you've got these sieve tubes between them right and this in this in the middle is pretty much I don't mean let me use a different color actually this in the middle is pretty much hollow right that these cells are actually alive yeah so these move food around the around the plant they have Nexen companion cells which look more like normal cells those basically have the nucleus and those do the normal cellular things what's in the middle actually lets things go through it's like a pipe yeah now on on this side you have the xylem right this eylem now this item looks very similar but the job of the xylem is actually actually to carry water and minerals so what you absorb from the soil from the roots up to the leaves and it's only in one direction right that's important phloem can actually carry things in any direction right it could go this way could go up could go down at cetera et cetera right the xylem only carries it the xylem only carries the water and the dissolved minerals to the leaves from the roots right sits in one direction okay and and xylem cells are fully dead right you can see there's no nucleus you can see that it doesn't look it doesn't look like you've got all this stuff going on like you do in the flower the xylem cells are dead the phloem cells are alive that's another big difference okay so transpiration transpiration is basically how water and and those dissolved minerals move throughout the plants so it all starts off in the roof remember we spoke about root hair cells taking in water right and obviously taking in anything that's dissolved in the water as well okay then what happens is the water goes from the roots up the xylem right like so and then into the leaves okay that's the basis of what happens but why does it do that okay you can think of this as sucking through a straw right but it's actually called the transpiration stream if we go back to our leaf diagram quickly yeah what's happening quite a lot is water and oxygen and carbon dioxide right are lost from here right mainly water and oxygen carbon dioxide is actually taken in quite a lot but it can be released as well because of respiration but we're losing a load of water more importantly from the leaf right if that's the matter is open well when that happens it creates a pressure difference it is like sucking for a straw right because it's connected right you've got the transpiration stream it's basically connected to this island vessel which is going up the stem and so when the water leaves it creates a pressure difference which causes water to come up to replace it okay so the water actually then comes up this wants to work them that would be great it then comes up the stem in order to replace it right and then down here the roots actually then absorb more water and then it and then it happens again more water is then lost from the leaves and it happens again and so that is the transpiration stream now what effects how fast that happens is basically diffusion right diffusion occurs for water to leave the leaves right to leave the Lea or to or to exit the leaves if you like into the air and this is a really common question most people will call it osmosis it's not as mostess because it's not happening through a partially permeable membrane it's actually diffusion right and there are four things you need to know that affect how fast that's happening one is wind if it's really windy then it moves water away from the leaf which increases the concentration gradient and so it happens faster if it's really humid right then water is there's low there's load of water outside the leaves if there's a load of water outside the leaves then the concentration gradient is lower and so it happens slower if the temperature is really hot right then it just happens quicker diffusion happens quicker also it means that the plant has probably opened its stomata which increases the rate of diffusion of the water out which increases the rate of transpiration and finally light has kind of the same effect it causes the stomata to open the plants open their stomata when it's light and that increases the rate of transpiration as well so all four of those things increase the rate of transpiration and that is about as far as we're going to go with plants so now let's have a look at communicable disease alright so what is a communal communicable even disease now this is a disease which can be passed on from one organism to another and they're caused by microorganisms right and we call those microorganisms pathogens now there can be things like viruses fungi bacteria protists and we're gonna go into those in a second a pathogen infects a host reproduces inside the host causes damage and then infects a new host right that's how they get around that's how they spread pathogens are adapted in many different ways to carry out their functions there's two examples here on the right at the top you have a what a drawing really of what a virus looks like and then a bottom you have a real-life example of fungi which have infected plant in this case and have sprouted a load of hyphae so everyone how do we actually spread disease well there's a few ways now if we look in the middle many are actually airborne right so airborne now this means that they can actually be transferred via the air if you call for you sneeze or even if you just breathe in talk then you can breathe out these pathogens and there you go and then infect something else many of these are actually viruses but they don't have to be viruses okay okay so how else well this one here dirty water right if you drink dirty water or even if you just take a bath in dirty water etc and then put your hand to your mouth you could ingest those pathogens cholera is a good example of that okay direct physical contact so this handshake is an example of direct contact if you haven't watched your hands or if you just come into contact with the pathogen you shake someone's hand and they've got it and either they put the hands of their mouth or whatever it is okay another one is contaminated food this is an obvious example of that right some bacteria or or or whatever it's going to be your fungi actually sprouts in the food and they grow in the food when you eat them then you are now sick finally their can be transferred by another animal or a vector right this is called a vector the reason I put a mosquito is because malaria is actually caused but I might call a microorganism which is a protist called Plasmodium but it is actually the mosquito that allows transfer from one organism to another okay so let's have a look at some examples of viruses or viral diseases okay first got moves measles now I've actually spelled that wrong there's meant to be an a there so that was telling me measles is a virus okay measles is something which is very very common and it is an airborne virus right you generally get it when you're a kid because it is very easy to transfer however once we have been infected once normally you don't become infected again and so that's why you you generally you're going to get those once okay what about HIV now luckily HIV is not as common HIV is an STD so it's a sexually transmitted disease and it's extremely bad there's no current cure at all treatment has gotten a lot better but what HIV actually does is it blocks your immunes your immune system from working by actually attacking your immune cells right this is really bad and it means you probably died of something else like a different kind of sickness and so that's not good TM b stands for tobacco mosaic virus now this is actually a virus which infects plants right which makes it interesting because it affects plants what it actually does is it affects the leaves mainly and you get all these black kind of spots that reduces the plant's capability of photosynthesis and therefore stops them from getting so much energy and therefore they'll eventually die okay so bacteria bacteria two examples here you've got Salmonella Salmonella this is actually a kind of illustration of salmonella but this is what it looks like and Salmonella you can get Viet your food it causes sickness it causes severe vomiting and stuff like that and generally via like the handling of food without washing your hands or something like that and so that's pretty bad Oh gonorrhea gonorrhea is another STI it's a very or STD or STI disease or infection it's a very very common STD but it's not very nice it is a bacterium what it actually does is it causes a yellowy discharge from the penis or from the vagina and that is obviously not very nice stuff it also makes urinating painful and so that's also not very nice oh good okay so fungi you have what's called ROS black spots right which which infects plants it causes these lesions which which are blackish or ROS black-ish should be like and that inhibits the growth of plants because photosynthesis is affected because the parts which have been affected can't carry out photosynthesis the leaves eventually drop off early and then eventually the the plant would die if it's not treated you can treat it you can actually treat it with fungicides and then you're okay athlete's foot is a common fungal infection in humans it is caused by a fungus and it is a problem because it cause irritation it causes your feet to smell and it can actually lead to worse conditions if you don't treat it it spread by contact like if you walk in a bathroom with with your feet off and you've got it then that's that's a way that it can be spread so in swimming pools is a very common way of passing it on okay protists right malaria is caused by a protists and let me just circle it here this here is the Plasmodium Plasmodium okay and that is actually the pathogen right it is a protist and what that means or what that is is a small single-celled microorganism right but it is different from viruses it is different from bacteria etc etc but Plasmodium doesn't just travel around in the air on its own in fact it uses a vector and that vector is this guy over here or I say guy it's actually a girl it is a female mosquito now female mosquitoes actually take in these Plasmodium and then when they go around and suck blood they can give you that pathogen which is not good malaria is a very serious condition okay but how can we actually stop them well that is a great question which I'm going to answer right now so the first line of defense is the skin right the skin is a great organ it covers your entire body it insulates you and protects you from pathogens right this skin is constantly dying and replacing itself so your alpha layers of skin fall off and then you produce new skin on the inside and so that is something that's constantly happening it also produces my antimicrobial compounds which fight pathogens and stop you from growing lesions of things on your skin so that's all well and good okay so tears and saliva contain enzymes which kill bacteria right those enzymes are called lysozyme so that's something useful mucus is also produced right so when you have phlegm and stuff like that that is actually mucus what it does is really sticky and it traps pathogens inside it and then we can swallow them once we swallow them there in the stomach well the stomach is full of stomach acid and stomach acid kills all those pathogens and that's all good right second line of defense are the phagocytes we talked about these earlier a tiny bit they're basically one type of white blood cells what they do is they engulf things which actually means they eat things they they kind of find the pathogens and they take them in and then they just but like basically digest them inside right they digest them just like we would digest our food they take them in and then they digest them and kill them okay so but they're not specific this is why we call them the second line of defense they're not specific they'll go around and they'll pretty much engulf anything which is not from us so they won't go around in and engulf our normal healthy cells but if we take in anything else or any other cell and they find it they'll just engulf it and so everything is fair game in that sense third line of defense are the lymphocytes and this is actually specific so the lymphocytes of white blood cells and they produce antibodies antibodies are proteins which have specific specific shapes on them right they bind to stuff they bind to what what is known as the antigen on a pathogen okay so if we look here you might be I say let me just actually zoom that in if we look over here this is our pathogen so this circle thing this blob might be a bacteria well these are the antigens right these little shapes on the end are the antigens now they have specific shapes and all cells have these things on the outside right all have these on the outside and basically your antibody or antibodies can be complementary to those so they'll go and basically bind them and so they are specific in that sense well why do we care about that well if they bind them then it basically can clump pathogens together so it stops them from going around and doing what they need to do also when they are bound to an antibody it actually causes the phagocyte so these guys to go and eat to whatever they're bound to and so that is good now it so happens that we actually maintain an immunological sorry memory of anything that we have produced antibodies are for so we're randomly producing these antibodies all the time and most of them aren't going and binding anything but if by chance one antibody does find a pathogen and bind to its antigen then we remember that right which means in the future if we come across that antigen again we can produce the antibody straight away otherwise it's just by chance right we're producing different antibodies all the time and eventually one of them's going to be complementary but during that time you might be infected by that pathogen but once you remember it you're going to respond to it ye quicker and that is actually the reason for vaccines so vaccines actually contain dead or inactive pathogens right vaccines obviously injections our body reacts as if they were real infections and it produces antibodies or lymphocytes for them right antibodies from lymphocytes right for those and so that means that eventually you have a memory of that antigen or / that pathogen but you don't you're not getting infected by it because they're actually dead or they're inactive but it means that if you come across the real thing another time in real life you already have the antibodies in order to attack it so that is great okay so how else do we treat conditions well one of the big ones is antibiotics right antibiotics so these are antibiotics an antibiotic will kill bacteria it won't kill viruses it won't kill fungi right you have antifungals for four funguses or for fungi sorry you have an and you have antivirals which kill viruses but but those are they kind of vary in how good but the problem is that bacteria can actually become resistant to antibiotics that is a very very bad thing right that's why okay and I've represented that with this picture down here that's why we don't use antibiotics unless we need to okay if you have an infected let's say you have a cold right colds are generally caused by viruses if you take antibiotics because you think it's gonna help well one it's not going to help – it means that you can have other bacteria becoming immune or becoming resistant sorry – that antibiotic okay that means in the future when you do have a problem and you take antibiotic you actually got bacteria which are resistant to it that's not a good thing okay so limit the amount of antibiotics you also take them in combination so take more than one different antibiotic at time drastically reduces the chance that you have any bacteria become resistant okay something else important is the painkiller painkillers are great because they kill pain right as the name says yes but they do not actually treat the condition whatsoever instead all they do is they alleviate that symptom so if you've got a headache can you take a painkiller great you're not actually curing the headache right whatever's causing the headache you know you're actually doing that but you are stopping yourself from being in so much pain and so that is a good thing but you can't use them to actually cure yourself of a condition okay so drug development importantly drugs take a very very long time to be developed right and so most potential drugs never make it to market because the testing is so strict and it takes so long the first thing the first thing that anyone does is computer modeling right they're basically model what the drug is going to do in real life but in a simulation okay they model it so that nothing is being harmed right next once once they've got something which they think is gonna work then they take it into a lab and they test it on cells and then maybe they test it on animals as well so that might be mice it might be flies it might be whatever right generally if it's a if it's a drug that's gonna work on humans you want to use a mammal so mice is a good one finally if all those are passed then you move on to human trials now the first phase is a small dose on healthy individuals right on healthy volunteer individuals and that's to test for side effects secondly if that is okay and you don't get horrible side effects then you use it a small dose of it on actual patients to test efficacy which just means how effective it is and dosage right because if you don't know exactly what those to use then you need to do these tests finally a larger pool of patience is tested to finalize that dosage and to make sure it's effective yeah and during those those trials they're generally blind trials which means that some of the people are actually given a drug which isn't the drug it's just like a tablet with nothing in it and then you can test for the differences between those people and the people who are actually given the real drug and if there's a big difference then great you think that the drugs working right generally you're gonna use a double-blind trial that's really important because it means that the people who are looking at the results or the doctors they don't know who was given the drug either all they're doing is looking for differences in in symptoms before and after taking whatever they've taken okay so monic monoclonal antibodies right if you're if you are not doing triple science you're not doing biology you may just ignore this part maybe fast-forward a little bit but a monoclonal antibody or a group of money money monoclonal antibodies there we go our antibodies which are identical right they're produced by fusing a mouse spleen cell with a myeloma cell right now is a cancer cell that forms what we call a hybrid oma now those antibodies are great for detecting things we use them in the pregnancy tests right they check they test for HCG which is a hormone and so that is all well and good they can also be used to target drugs in a very specific way right they can target parts of our body in very specific ways because they are very specific themselves they can go and bind to something we can tell them to go and bind to a certain type of cell for example however research on that kind of thing is still ongoing you do need to know how we produce them well a mouse is first injected with an antigen right in the antigen obviously is what you want your antibodies to to detect or to attack or whatever it is and then you fuse the spleen cells of that Mouse which has been injected with myeloma cancer cells and you form would call hybridoma cells right via a cell fusion okay then those hybridoma cells okay they are going to grow your antibodies and so you harvest them or you culture in a medium that allows them to survive but it doesn't allow other cells to survive because all you want is those cells that have actually fused what you would also have is the spleen cells in the myeloma cells which have infused and you don't want those so you make sure that you only allow us to survive then you take out the antibodies and that is your product done ok Delk and so finally this is pretty much the last section right we're gonna have a look at photosynthesis and respiration so photosynthesis is a chemical reaction right green plants and algae to it they turn carbon dioxide and water into glucose oxygen right using energy from sunlight this is an endothermic reaction endothermic just means a reaction in which energy is taken in from the surroundings so here are the equations water plus carbon dioxide in the presence of sunlight that's my great joy now makes glucose and oxygen and I've given you the simple equation learn that if you want to otherwise don't bother and so here we go this on the left is algae and that on the right is a plant I don't need to tell you that by the way what would surprise you is that most of the oxygen that's produced via photosynthesis in the world is by algae not by plants because overall you have a massive volume of algae where there is a water supply ok so rate of photosynthesis the rate of photosynthesis right so how quick photosynthesis actually happens is limited to by several factors those being temperature carbon dioxide sunlight and chlorophyll or ice the amount of chlorophyll they've got because remember chlorophyll is what absorbs the sunlight and so they need that all right you need to know the shapes of the graphs or the relationships between those factors and the rate of photosynthesis now this is very important right if it's limited by these factors then these are called limiting factors limiting factors right so first of all rates of photosynthesis versus carbon dioxide concentration as you increase the carbon dioxide concentration the rate of photosynthesis will increase until finally you've given it enough carbon dioxide that it flattens off right what does that actually mean well it means at that point something else is limiting the rate of photosynthesis okay that's what that really means it means you've got enough calm outside that maybe one of the other things so sunlight is limiting photosynthesis at that point right so at this point you've got so much co2 but now if you increase sunlight you're gonna you're going to increase the rate of photosynthesis instead and so there's the graph of that surprised looks exactly the same right the the light intensity or the amount of sunlight as you increase it the red photosynthesis increases until that is no longer the limiting factor and now something else is limiting it right well what's that something else it might be the amout of chlorophyll right and so there you go there's the same relationship again as you increase the amount of chlorophyll the Reds photosynthesis is going to increase as well obviously you can't just add chlorophyll and increase it right you're actually talking about the amount of chlorophyll in the plant and so that's actually quite difficult difficult experiments to do if you like but those three things have kind of the same relationship to the right photosynthesis what doesn't is temperature okay now you probably recognize this graph it looks identical to the shape of the enzyme graph that we looked at earlier right that's because that's because sorry it is identical because photosynthesis is a bunch of chemical reactions which are controlled by enzymes okay so that means that when it's really cold the rate of reaction is really really slow but it doesn't mean that it doesn't happen at all right it happens but it's just not long now as you increase the temperature the rate of reaction increases quite exponentially right it is a curve and then when you get to like 50 degrees it goes all the way down because enzymes get denatured at that point right you have an optimum temperature for enzymes which is going to give you a fastest rate of photosynthesis after that it start to break down and that is that now photosynthesis produces glucose what do we use glucose for or what applies use blue clothes for as well they use it for respiration remember aerobic respiration is how organisms obtain energy also anaerobic respiration but respiration in general they obtain energy by releasing the energy stored in glucose okay you can also use glucose put load of glucose together and turn it into something else and you'll get fast right also you can add glucose to nitrates to form amino acids those amino acids can then be used to make proteins okay but you need to have nitrates hence why plants need nitrates also glucose is just put together to make start right starch is obviously the storage molecule of glucose in plants is not in animals in animals its glycogen but in plants its starch right they add a lot of glucose together to make starch and then that and then when they need energy then they break the starts back down again on the other hand cellulose if you put a load of glucose together but in a different way so in a different shape you actually make the insoluble carbohydrate called cellulose that makes the cell walls and so that is why you use it so respiration we are going to move on now as a quick a quick note vatapΓ‘ into respiration so respiration is not the same thing as breathing this is one really common misconception right respiration and breathing are not the same thing respiration is a chemical reaction which releases the energy stored in the glucose right so photosynthesis makes glucose respiration releases the energy in the glucose right they're kind of the opposite of each other it allows us to carry out processes which require energy which is great and so here are the world equations again am writing is a lot better this time so glucose plus oxygen gives out energy making carbon dioxide and water and there is the symbol equation again I don't have to read that out to you Arabic respiration requires oxygen right and occurs in the mitochondrion cells our cells carry this out all the time right it's not like photosynthesis rate can only happen in sunlight we're always burning energy right our cells are always doing something we're always moving even when we're asleep we're moving right because you're breathing and and all that good stuff requires energy and so it always carrying out respiration the reaction is exothermic because it releases energy right which is the opposite of photosynthesis the more energy we meet we need the more glucose and oxygen we need to allow respiration to occur and that's why we eat and why we breathe right there's the difference between breathing respiration you breathe in order to get oxygen in order to use it for respiration they're not the same thing okay anaerobic respiration well that is or sometimes it happens sorry when you're out of breath right if you're sprinting we can't get enough oxygen etc we start respiring anaerobically that's because you don't have enough oxygen this produces lactic acid which caused us to fatigue and cramp up it doesn't last long that's why we can't sprint very long right glucose actually forms lactic acid that's the whole equation of reaction and you give out energy right just like in any other respiration however anaerobic respiration only gives out a small amount of energy 5% of the energy of air over respiration so it's not as good anaerobic respiration right when you have finished you need to get rid of the lactic acid well the way you get rid of the lactic acid is you react it with oxygen for that reason when you are full of lactic acid and you've just been sprinting and stuff you will be breathing really really heavily and that's so you can get extra oxygen right you can keep doing that too you've recovered the amount of oxygen you need to clear all that lactic acid is known as your oxygen debt right your oxygen debt is the amount of lack of oxygen so you need to clear your lactic acid that also by the way releases the rest of the energy which is great anaerobic respiration is different implants and yeast though they carry it out in a different way they don't produce lactic acid instead they produce ethanol and carbon dioxide right we call that process fermentation so when are you probably heard of it whenever you hear about things fermenting or fermentation is actually the anaerobic respiration in plants or in use useful for us because we can use the co2 produced to cause bread to rise and we can also use the ethanol produced to brew beer or make wine right and so that is a good thing okay okay we all by the way we can't use that ethanol to produce things like vodka and spirits because we don't get a high enough percentage out of fermentation in order to do that okay so finally finally met metabolism metabolism is the sum total of all the chemical reactions that happen either in a cell or in an entire an organism right so these reactions include digestion respiration protein synthesis etc right so all the chemical reactions you can think of add those up and that is metabolism some reactions do not require much energy typically those are breakdown reactions right for example respiration actually releases energy rather than uses it others typically typically do require energy ones which make things so synthesis reactions typically require energy okay so breakdown reactions including breaking down proteins right protein breakdown amino acid breakdown so breaking amino acids down into like glucose and into some other stuff and lipid respiration so burning lipids in in order to produce energy right those do not require energy however synthesis reactions where you make stuff including glucose being converted into starch and cellulose and in animals being converted into glycogen those require energy right those are synthesis reactions rather than breakdown reactions lipid synthesis involves making fats from fatty acids and glycerol requires energy protein synthesis right glucose and nitrates are used to make amino acids and amino acids are put together at the ribosome to form proteins and that is also a synthesis reaction that requires quite a lots of energy and so deep breath that is actually it's right that is all the content that you need aside from the required practicals which is going to be covered in another video that is all the content you need for paper one of biology I hope you've managed to keep up with that I've had great fun just talking as fast as I can and ruining my voice as a result but I hope that has really helped you guys please feel free to put any comments in the box below or send me a direct email as usual please like and subscribe the page because that really does help me out obviously follow me on Instagram and all that good stuff as well because that would be great you will be obviously notified of any new videos that come available so it's useful for you as it is for me but I look forward to seeing you in the next video

35 thoughts on “FULL PAPER! All Biology Paper 1 Content – GCSE (9-1) AQA Biology / Science

  1. Great video, but i have one question when talking about the esophagus you said that it "just connects your mouth to your stomach….. that's pretty much its only job". 23:57 We were taught about peristalsis in school, could someone explain that to me?

  2. No offence but your face is too close to the mic please move further away but except from that thank you for the crash course it's very useful.

  3. Did my biology paper 1 yesterday and went in feeling really confident, couldn't of done it without your help. Thank you so much πŸ‘

  4. OMG!!! This video really helped 😭 had my exam today please can u do one for chemistry paper 1 my exam is on Thursday 😭😭😭 no other YouTube video helps this one really did

  5. just finished my exam and LORD THAT SHIt ugh… i feel medium about it. ( i do foundation combined) wtf was that shit on the digestive system? also i forgot all the root hair cell thing and im so mad at myself

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