everyone welcome back my name is jesse i am a tutor in melbourne and i also make gamsat videos and crash course videos like this to help people prepare for section 3 of the gamsat science section today what we're going to do is actually go through the very last of the biology crash course series which has happened very very quickly this will be the fourth installment over the course of just four weeks basically and i've already done these for chemistry and physics as well and we kind of kept them down to about three and a half to four hours or so to really prove that you can condense the theory that you actually require for the test into a relatively short amount of uh of content of course this is stripped back it is just the bare essentials and realistically the highest yield stuff there may be little bits and pieces that you might find in a question but has it been repeated no so we're really looking at people with a non-science background can kind of go through these videos brush up on all the skills so that they know what they're actually supposed to be studying for because the world of chemistry physics and biology is very very broad and there's really not that many things that uh dems that's really requiring of people we're seeing in the new structure that they're definitely introducing concepts to what we focus on in this is getting you familiar with those concepts so that you're not relying on learning information at the same time that you apply it if you would go in blindly into the gamsat with no prior knowledge then it would be very tricky to actually navigate the information and every now and then we do find that they do test some prior knowledge but for the most part it is a reasoning test you want to be focused though on actually applying the reasoning not any kind of learning so with the bio one we know that it's much much less content based for sure compared to something like say chemistry and so with this series it's a little bit different in that we are looking at familiarity with the words understanding how cells function understanding how systems function so that when you go into the actual information you kind of have those basic assumptions under your belt and as well as that you're not going to be thrown or phased by any of the wording that's used so with today's one anyway it's a bit of a mishmash of topics really we've gone through and themed all the previous ones but today's one is really just a bit of a mishmash of topics that are kind of left over that didn't really fit in anywhere perfectly i figured that would happen bio is a pretty big topic and so we're going to go through a bit of a mix of things we're going to start with gene expression which kind of links into a bit of the genetics from the second one from the first one actually that was then we did cell structure a second then we're going to go through enzyme activity and how enzymes function as well because they seem to come up a lot in gamsat questions we want to be familiar with those then we're going to go through how to read hormonal and neural maps as well in terms of cell signaling and excitation and inhibition or stimulation and inhibition and then finally we're going to end on some metabolism and photosynthesis because again it's a little bit more theory based but we see that some assumptions and knowledge in this can be helpful in gamsat as well so i'm going to try and keep it relatively short hopefully we're going to aim for about 40 minutes or so to get this one knocked out and then you'll be on your way to answering questions all right so the first thing that we're going to do is go through gene expression and what this really is this is a very very useful topic because although it may not always be assessed in terms of just translating say the nucleotide based sequence code backwards and forwards it is really important to understand the basics of what gene expression is because it underpins a lot of the questions relating to genetics and you can extrapolate from here so the first thing is what is it it's really just the process of how we take dna into a final protein product right and there's two key steps i'm going to leave out there is a third step but i'm going to leave that one out because i don't see it as relevant to gamsat i'll mention it when we come up to it so that you can research it if you want to but i don't think it's all that useful the first one is how we convert dna into mrna and this process that takes us through this is transcription and so we'll look at that first that's going to be step one now along the way here we technically do modify the mrna and that's the step that i'm going to leave out because if it gets thrown in they will introduce any key facts that you need for the question and you'd probably be fine to work with the information given i don't think it's worth knowing it it's a bit too technical and a bit too theoretical the second step then takes us from mrna into polypeptide or really just a sequence of amino acids that can fold into a protein so this is going to be translation and that will be our step two that we'll go through so starting off with transcription i'm just going to zoom in here we start with our dna compound yeah this will be our dna now really dna is a very very long long molecule but along the way sections of it will be genes and we've talked about this in the first of the bio crash course series and so we've now isolated one of these genes we're just looking at part of it and it's obviously very very short most genes are going to be in the hundreds to even thousands of nucleotides long we're only drawing tennis or so so obviously a much simplified version of it and so i'll point out we've mentioned these before we have three and five prime end these are just ways to identify which end of the compound we're talking about it relates a little bit to the structure the five prime end has a free phosphate and the three prime end has a free sugar on its end it's pretty unlikely for that to be all that relevant to a gamsat question though but i put these in so that we can kind of distinguish where we are and so on one end we're going to have this red circle here which is going to be an enzyme called rna polymerase now again you don't have to memorize names or anything like that i'm just going to reference them so that you're familiar with the words so that if they do talk about that you already have heard the word before you don't need to go memorizing what rna polymerase is and how it functions and all the rest of it they will guide you through that in the stem we just want to understand what the process here is so this enzyme will actually attach to one of the two strands in this case this bottom one and what it's going to do is it's going to run along the dna and read it and then lay down complementary rna nucleotides which we talked about so remember that the code is a to t g to c and vice versa but because we're dealing with mrna we don't actually have thiamine in there we have uracil instead uracil and so this will be the u and so if i make up for example a nice simple one let's do t a c and then uh we'll just make up stuff like g c a t t a c or g there we go so complementary to that we'll do that on the other side i might just color code this would have been a t g c and then to c would have been g t a a t c like that right so that's all pretty familiar and so as the rna polymerase runs along what it's going to do is lay down complementary mrna so what i might do here just to make life a little bit easier for myself is hopefully grab it all just about just going to bring that up a little bit to create a bit of space and there we go cool all right and so as it runs along let's say it's already kind of started its way along and opposite to t it would have laid down uh a an a opposite to a it would have laid down a u and then opposite to c it would have laid down a g like this aug and it's going to keep going right so if it continues to slide along then next up it would see g and so it'll put down a c and so on like this right like there then a a u and oop c just like that and this here is going to be our mrna molecule like that now you might notice a pattern right of course it's complementary to the bottom strand but it's also effectively identical to the top strand that got kicked out of the way right in the process so the reason why as well i forgot to mention it uh it bubbles out like this just so that it can access the dna but that bubble will run along and re-close behind it so i've not really drawn it correctly because further down here by the time it reaches this point the bubble will have opened there to access the dna but i can't really animate it too well with a diagram but i would recommend i'll link below as well some youtube videos that do a really good job of showing that animation much better than i can do here so you can watch those as well the other thing that you can watch is if you go to like my super super old videos although that was only like four months ago i started this channel really just making videos for my high school students and so for my bio students i put together a three-part series going through transcription modification and translation if you want to watch those i'll link those below as well actually that will probably be easier you can watch those they're in a lot more detail so you definitely wouldn't need to know them in quite the same detail because that's for my vce students but um in it i have a pretty good animation of where i i drew rna polymerase on my finger and used an analogy of a resealable sandwich bag for this particular thing that might be helpful so watch that one as well but once it gets to the end everything kind of drops off and so we end up with this strand here and so the mrna you can see is actually completely identical to this purple strand all the way along the only difference is that where we have t's we should have u's and in fact i made a slight error there that should be a u because this is mrna whereas this is just dna like that and so this thing creates a little bit of uh naming structure which you want to be familiar with because they will probably use it if they go into this topic and that is that the bottom strand here because it's being read by the rna polymerase then it's acting as a template so it's often called the template strand and so therefore the other strand of dna would then be the non-template strand like that annoyingly though there's a second naming system and it flips what is none so as well as that you'll notice that the top strand the non-template strand is also identical to the mrna i.e it codes for the mrna so this is often referred to as the coding strand and because the bottom strand is opposite to it it's often referred to as the non-coding strand so they're two different naming systems that you can use and you might see either one used in a gamsat question so be ready for that there we go cool some minor things that i don't think are all that useful but i'll throw them in anyway is our rna polymerase you'll notice started on the three prime end it always reads three to five and then it'll write new information five to three because dna and mrna should always be anti-parallel like that so the enzyme always look red enzyme always reads three prime to five prime but it writes down complementary dna in the new stuff from five prime to three prime just like that that's a good tip to uh to call on in case you get anything in terms of orienting where you're at so this is our transcription process we've now used the dna as the template to write out mrna the reason why we do this is because our protein manufacturing system cannot read dna can only read mrna so effectively it's like it's in the wrong language and we need to translate it a bit annoying because it's translation is the next step which is different but um we're trying to transcribe ends transcription rewrite it in a new language mrna language and that will be this red compound that will then jump off and the dna will snap back together so the dna is not damaged in the process it's just used in the process so then we get to transcription and this one is a little bit more dynamic there's a little bit more going on so what i've got drawn here is this is my artist's rendition of a ribosome and we mentioned in the second crash course series about the fact that ribosomes key function is to manufacture protein and now we can actually look at how it does that so if this is our mrna here in red right let's just say that it's the exact same as what we just had up here so it's going to be a u g c g u a a u c and what it's going to do is it's going to read it in triplets at a time so it's going to read this one this one and this one we'll just kind of chop it up and in fact that one should be kind of kicked out to the the outside let's just move that one a little bit like this okay cool and so we have three different regions of the thing now the ribosome i'm not really too fussed about again the details of that they're not really going to pick on your knowledge of the structure of a ribosome all we want to understand is why is it that mrna is turning into protein how does that actually happen so it does it via trna which is another rna molecule which carries with it a specific amino acid remember that proteins are just a chain of amino acids stuck together and then folded up into a shape so i always remember aug here because my birthday is in august so i remember my life started in august and therefore every single protein starts with aug weirdly the code on the mrna is always aug so complementary to that let's do another color here would be a so it'll be u a c that would be part of the trna molecule they kind of have this weird kind of t or cross shape and then it's carrying on it a particular amino acid which we're just going to use little shapes for the moment and the idea is that the trna is brought in because it's complementary to the mrna and then it'll read the next triplet and that will be corresponding to a complementary code of let's see c would go to g c and then a and the trna that has that in its sequence will carry a different amino acid right so it might carry i'll do a triangle and what will happen is there'll be a joining between those amino acids and the trna will get kicked out all that really matters is we're using the mrna to attract in or bring in the correct trna carrying a specific amino acid which allows us to control the sequence of amino acids in the protein as this chain keeps growing and the ribosome runs along the mrna strand then this polypeptide many peptide links between the amino acids will get larger and larger and then it'll fold into a protein and that is the translation process and there we go and that's it so the whole thing of gene expression is just being able to switch on a gene and then transcribe it into mrna and then translate that mrna into a polypeptide which turns into a functional protein there we go any errors in that process can lead to a non-functional or misfunctional protein as well and that can have some kind of consequences but we don't need to be able to predict the specific consequences so then the next thing is enzymes so enzymes come up a lot in the different questions you'll probably be throwing some random enzymes that you're not familiar with that's totally fine a good trick though is enzymes often end in ase so if ever you see a's at the end lipase protease that kind of thing then they all must be enzymes but not all enzymes end in asa so you've got things like pepsin for example um which does not end in ase but is an enzyme but if it does end in ase you know it's going to be an enzyme so there are special type of protein actually so they would be manufactured in the same way that we saw before as other non-enzyme proteins what they do is they increase the rate of reaction and they also decrease the activation energy of a reaction i.e they lower the amount of energy required to get that reaction to go forward so we can think of them as like a biological catalyst effectively so a catalyst in chemistry just means any compound that decreases the activation energy and therefore raises the rate of reaction enzymes are a special biological type of catalyst they're a protein catalyst and so i've put in here an example of what's called an energy profile diagram and you may get thrown one of these but it's pretty again pretty unlikely that you need to come in with prior knowledge you can usually work with them but just as a visual the idea is that over here we have energy level in arbitrary units and over here we just have reaction progress right you can measure energy in kilojoules and stuff but we're not going to fuss about the maths on it as the reaction goes so we've got the first straight line is the energy of the reactants the last straight line is the energy of the product and the change in between is what happens as the reaction progresses so the black solid line is if it were to be uncatalyzed it requires an amount of activation energy often written as ea but then once it reaches its peak it then drops and it loses some energy as the bonds form or break and then you end up with a new amount of energy right this is an example of something called an exothermic reaction which we've already covered in the chemistry crash course video so i'll link that as well where there's an overall loss of energy and the overall change is from the starting point to the ending point that's the enthalpy which in this case is negative because it's a drop what we're more interested in is what happens when you add a catalyst so the catalyst is shown with the red line and you can see that it's lowering the peak energy so the activation energy doesn't have to get quite as high in the catalyzed reaction but otherwise the line goes in the same position everywhere else it meets back up with the curve and it does not change the energy level of the reactants and the products because it's not changing the outcome of the reaction it's just changing the amount of energy required and also how quickly that reaction takes place the way that it does that is it often holds on to a compound called its substrate using an active site and an active site should always be complementary to a substrate kind of like lego blocks kind of tessellating or fitting together and what it does is it holds onto the substrate and therefore increases the likelihood of its reactive surface meeting another compound and when we look at things like collision theory we say that you know the more successful collisions there are per second the higher the rate we've talked about that before as well so if you've got an enzyme that is literally orienting a compound for you then it's reducing the variability of how they can interact and therefore increasing the likelihood of a successful collision with the right amount of energy and then the right uh the right orientation as well and this is how it helps so if we draw that out let's say we have an enzyme like this that kind of looks like pac-man so it's a bit wonky this is going to be our enzyme this here would be the active site this kind of region and so we need a substrate that is complementary to it and so if i draw out for example a bunch of different compounds this maybe would test like quite well it could actually fit there but even better would be something that reacts with the whole surface like this all right it doesn't have to complete a circle either it could be something you know it could be doing like this it doesn't matter the idea is it's in contact with that reactive surface of the enzyme or the active site like that so this would be our substrate right if it doesn't tessellate well it's not the right substrate for it every enzyme has a specific substrate that it works with but often they can also bind some other similarly shaped compounds which might then prevent its action and like inhibit or block it in some way then finally we need to just understand with enzymes when they're functioning they're very particular they require very specific ph and temperature levels often referred to as optimum conditions so i've drawn two graphs in one here and this is more of a theoretical understanding of it we want to understand what happens to enzyme activity under varying temperature and under varying ph under varying temperature there's a window of temperature that is perfect for it that'll that it'll work out very very actively but then as you lower the temperature the enzyme will start to become dormant we'll say it's almost like uh you know it's like freezing it and it going cold and stiff and not being able to move in any way but you can throw it back out and you can raise the temperature and its activity will come right back if you raise the temperature beyond its limits it will actually start to denature that protein or denature that enzyme and it'll actually interfere with its structure so that it can no longer bind its substrate and it becomes non-functional so too higher temperature and you can effectively burn or boil your your enzyme and that is denaturation so what i do with the red line here is if this axis here is temperature and this axis here is just arbitrary activity we can see that as you raise the temperature it becomes more and more active until it reaches its peak or optimum temperature and there's some kind of range where it's pretty high that's its optimum range but then once you go too high it just very quickly dips off and that's because the protein is denaturing the important thing is denaturation is irreversible once you've denatured your protein you can't get it back you need to get new protein at that point and so i use this graph because if you think about it if you were down here on the hill you can walk up the hill right you can regain that activity if you roll off the hill you lower the temperature you can just walk right back it's a slow gradual process if you look at the other side it's a very steep drop-off if you raise the temperature too high and you fall off of the side there there is no getting back so it's just an analogy for it but often you see quite a steep drop off like this with high temp too the other one then is the pink graph and that is with ph variation so if we change this axis now to ph this one has a steep drop off on both sides so it's not going to actually look like a rectangle in terms of its activity graph but again it's that analogy it's got an optimum ph range right that it'll work at but then once you go too low i.e too acidic you can actually denature the protein just like that in the same way and you can't get back you can't climb back up that if you raise the ph too high and you go too alkaline or too basic you can also denature the protein so it denatures on both ends so it's a lot more sensitive to ph in that sense and so we just want to understand this because if you got a question that was in the answer say mentioning something about high temperature you know that that may cause denaturation and that may then impact the um your reasoning for the answer i can't really give you a specific one because every enzyme has a different optimum temperature and optimum ph range so it depends on the one but they would probably give you a graph or give you some information they're not expecting you to just randomly know which ones they are although if there was anything that was potentially helpful any of the enzymes that operate in the body probably have an optimum temperature somewhere around body temperature of you know 36 37 degrees if you lower the temperature or raise it beyond say to 40 degrees or 50 degrees then you're probably going to be denaturing that protein at that point that's a good way to look at it if it's a protein that's in the blood even though you don't need to know the ph of the blood it is good to know that the ph of blood is around about 7.4 and so again if you have to guess at what the optimum ph is for an enzyme operating in the blood then it would probably be around the 7.4 mark right it might prefer 7.2 but you know 7.4 it hasn't fully denatured at that point we see some variation in it all right the next one then is very much a skill rather than theory but it does come under the the label of biology so hormone maps so when we're looking at hormonal maps we talked about the endocrine system in the last video on all different body systems you can have stimulation and inhibition as the two key outcomes they're often represented as pluses and minuses in little circles but sometimes stimulation is also shown as an arrowhead and inhibition is shown as a blunt or flat end like this as well usually you'll see this from from gamsat from what i've seen but you may see this as well so we're going to be ready for both what we want to be able to do is really quickly analyze hormonal maps so that we're not relying on the context of the question because otherwise that becomes too question specific you want to be able to look at these as a problem solver so that you can adapt it to any kind of hormonal map question and then we'll also look at neural maps which work in pretty much the exact same way so i like to think of even though a hormone is not really an on off switch you can analyze these maps like on off switches otherwise you can use increased decrease notation as well or more or less is something that i often use so if we look at this one you don't really need to come into it with any knowledge of what any of this actually means you might recognize this is from a previous sample section 3 video that i did it's just a really good demonstration of the ways in which enzymes can operate so if we look at for example renin over here we'll just pick a random one right it's got a stimulatory response on this process this conversion so all we need to really be able to do is know what happens when you increase one of these enzymes so if i increase the amount of renin then i get more of this and i like to think of stimulation as working directly and inhibition working oppositely meaning that if you've got a stimulatory path more of it means more stimulation less of it means less right if you've got an inhibitory path more inhibition means less of its output and less inhibition means more of its output so it goes in reverse right and that's a really simple way of breaking down these kind of these kind of maps so if i have more ring and because it's stimulatory then i know that i can just follow the path of it's like an on switch right so it's on so more i like to do arrows more of this then this goes more of this there's just more arrows which then means more of this more of this more of this or if there's more of this and i can just keep tracking the impact as i go around the loop like that right and so therefore i can make a statement that more maureen and means say more aldosterone and secretion done there we go and the idea is the question will hint at where you're starting and where you need to end and you just follow the map through that path if we look at an inhibitory pathway instead let's say we look at and i'll do it in red as well why not uh let's look at say the inhibition of the kidneys here that is coming from water and salt retention all right so this is going to be a particular stimulus and so if we've got say more water and salt retention we've now got an off switch so we get this gets shut down right so therefore we get less renin and because this is all positive it keeps going less less less less less and less like that now obviously that's a quite simple one there so let's just create a slightly more complex one without any context for the biology so say that we just have all these little blocks and i don't really know where this is going i'll just make it up and see what happens so let's just call them enzyme a b c d e and f and then i might as well color code it as well so it's a little bit easier to track we're going to go stimulation stimulation stimulation and maybe stimulation here but then i'm also going to put in some inhibitory paths as well so inhibition inhibition inhibition and inhibition like that and now i'm going to see what happens let's say that we do an increase in a what's that going to do to say f right and so all we have to do here i'm going blue so if we increase this i'm trying to get over here so i follow the arrows around and i go right positive so that has the same impact right then from there because this is inhibitory you're going to get the opposite effect right so if i've got more of b then i get more uh inhibition of d which means i get less d and then because that's got an inhibitory effect it's going to flip back around again i get more so therefore an increase in a means an increase in f done it shows that you don't have to have any actual biological knowledge at all to read a hormonal pathway you just have to think about them as on-off switches or ups and downs positives continue doing the up arrow or the down arrow whichever you started with whenever it flips to negative it means flip the arrow around it's a nice really fast way to break down hormonal and neural maps and so we can do the exact same thing if we have a neural map here right we can do the same thing we don't have to know what any of this actually means and truthfully i did a neuroscience major and i can't remember um some of these i can recognize a few of those names but all the details of neuroscience just dropped very very quickly for me i never used it again so uh if we were to look at say this one on the left right uh we can do the same thing we've got so red is going to be uh stimulatory and it's a little bit counter-intuitive but i've just grabbed this off the internet so who knows where it came from blue is going to be inhibitory each time right so a little bit counterintuitive on the colors but we'll go with it so let's say we have an increase in glutamate to start with and we'll just trace it around and let's see what's going to be the impact on the gpe which can i remember what that actually stands for i don't think so gpe no can't remember at all so if i have more of this then i'm going to trace i'm trying to get to here so i can see some arrows pointing down this way and then i can also see there's another path that goes out this way and i can loop in here so i'm going to look at both of those and see about their impacts so if i have more glutamate then it means i have more excitation of the striatum if i go down the d2 receptor this way then it means i have less stimulation of gpe because i have more inhibition of it right so all of my arrows are to do with stimulation so lower means inhibition if i have less inhibition from there then uh that was a decrease if i follow a different path i can also go this way we said right and so if i do that i've got cortex being stimulated that has an excitatory impact on the stn and therefore that then has looks like an excitatory i would say as well because there's no blue and it's got an arrow head that would be an increase so because i've got a decrease in increase that is in some ways kind of ambiguous i've picked this out at random so you may not get one quite as complicated as this but then another thing to consider is you've also got this little indirect gaba pathway going here as well so from the first one there was a decrease in gpe which means then an increase in stn and therefore an increase in gpe the other one was an excitation here so an excitation of gpe which would mean more inhibition which would mean a decrease so again it's a bit ambiguous from that one so this could happen in an answer it would just mean that it wouldn't give you a conclusive answer which would mean that it probably isn't the right one in that case and then finally it's just metabolism and photosynthesis so this is again a point of theory but we just want to draw out some of the key takeaways from each of these processes so that we can apply them in the bio questions so with metabolism it's actually a breakdown of two different processes we've got catabolism which is the breakdown of compounds and the freeing of electrons from bonds whereas we've also got anabolism which is the build up the gluing together of things put those two together and you get metabolism like that so the build-up and breakdown so it's both the storage or the formation of sugars for energy storage or carbohydrates i should say and then it's also about the breakdown of them and their use in the muscles and the tissues so if we look at basic metabolism what we're doing is we're taking glucose and we're putting it through a process called glycolysis this is happening in the cells and then this breaks it down we'll do a couple of little details but again i wouldn't necessarily go in memorizing all of this two lots of a compound called pyruvate when we get the pyruvate in that process we actually produce or we net produce two atp and you've probably seen these in the questions before atp is a compound that actually stores electrons for us and therefore is referred to as an energy carrier and we use these as a way of protecting the electrons so that we can transfer them between compounds for use and so our whole goal is to build up atp stores right so this is when we're actually spending that glucose and getting that atp out so that we can send it off to the tissues to be used or it might already be at the tissues the pyruvate though can keep getting processed further right so it gets processed into acetyl coenzyme a and again don't bother memorizing any of this and then it sends into another cycle called the krebs cycle and this actually occurs in the mitochondria and i forgot in my cell structure video to mention mitochondria is one of the key one of the key organelles and the fact that it is the powerhouse of the cell which we've heard before so krebs cycle actually keeps making more atp right and other energy carriers which we don't really care about their details and then from that we spend a little bit we sacrifice a little bit of that energy we then go further still in the mitochondria and then we have another thing called the electron transport chain or etc and from that we get quite a bit more we get 32 to 34 atp all the numbers are totally useless you don't need to know them but it's just to give you a sense of where most of our energy comes from right we get very little out of glycolysis we get a lot more out of the electron transport chain and all of this happens in the mitochondria right so the mitochondria is where we get the bulk of our energy production once we get to the end though we've spent the energy and that's it then we have to go finding more glucose or finding more stores of glucose and that's why we have a diet right if we look at plants that always say energetically plants are much much better than humans and all other animals because they actually generate and recycle their energy to produce their own food so they're not dependent on a diet they can actually generate it from the energy that they make so what plants will do is they also squeeze out an extra step they get photosynthesis and what they're doing in photosynthesis which i'm sure you're already familiar with the basic concepts that is storing energy from uv light in its own photosystems for then use right that produces energy carriers and so it does that in the chloroplasts but remember that plant cells also have mitochondria and everything else so they can do everything that we can do they just add on an extra step and in that process they get another effective run of the electron transport chain so they really pump atp out of their their sugars and in doing that so they have uv light goes in and then out of that they get another 32 to 34 atp out of that system and then on top of that what they're also doing after that is they're spending a little bit of it and not all of it but then they're converting co2 into glucose so they can actually make their own food at the same time and then that food goes right back into their metabolic cycle which is just like ours so they can actually take that glucose and send it right back and then start processing it to generate more energy from it again so they have the full deal of it right some of the key factors that go into photosynthesis though it's probably worth knowing the chemical equation just in case so it's or six co2 if we want to balance it we may as well plus six waters goes into six carbon oh not carbon dioxide six oxygens plus one glucose and the idea is that when we respire or spend our energy we're actually going this way we're reversing it we're using glucose and breathing in oxygen to spit out co2 and we also make water in the process plants do that but then they also need water so that they can fix carbon dioxide and fix it into a fuel for themselves just like that that's the basics of it and a nice little kind of wrap up is if i just do a nice little drawing of a tree here like this here's our photosynthesizing tree here's our human this is how we interact with it it's spitting out oxygen we're breathing that oxygen in we're then spitting out co2 and it's fixing the co2 like that right as well as that we kind of eat the plant we probably don't eat trees but as now say it's never broccoli we get glucose out of it right and we get other sugars and fuels and then from that we spit out water let's just say it comes out in urine for example and then we use that water it's not quite how it is but there's a nice interaction there we use that water we water the plants and they can store that water use it to then reproduce at the same time cool and we get this nice little interaction between them it's possible you may get a question relating to some kind of interaction but it's very very minor i figured i'd just throw that one in there though to give it some context and there we go that's that's the basics of everything right so yes metabolism is a much much bigger topic but i don't think that it's all that relevant to know every little step it probably speeds up your familiarity with processing the question for sure but from the questions that i've seen about metabolism they're actually not biorelated they're more chemistry related and in that case you're just looking at patterns so you don't really need to be familiar with the compounds it definitely helps if you want to go and look at that then be my guest but i don't think that there's all that much value for the or much reward for the effort that goes into it so realistically you could probably go into a chemistry metabolism question just looking at it as a pattern recognition thing rather than having to know a lot of the deep background behind it but there we go so that then wraps everything up you can see that biology is much more skills based there's only a few points of of theory along the way that you need to to know and so hopefully this crash course series has wrapped that up for you and helped kind of define the limits of what you need for gamsat as always though this really is the bare bones of the principles that you need i'm definitely not saying that if you watch these videos that you'll suddenly be guaranteed a boost in your section 3 score is ultimately about problem solving but now you've actually got the skills that you can use to start grappling with those questions and processing the information if you're to go in blind it's very very confusing and you'll notice that you don't actually use a lot of the theory all that much it's just there to confirm your thinking or to speed up your answering the only place that i would say that you really use theory a lot more is in the chemistry questions it lends itself to it but it's still not the majority of the questions for the most part it's problem-solving anyway hopefully you've enjoyed this one as well leave me some feedback on the series i've had a bit of a request to do a maths crash course series so i'll probably look into doing that it'll probably be early next year though because i'm planning to go on a break pretty soon at the end of this week but um i will work on that one as well that should be a pretty interesting one i've also got a set of a playlist for the other two maps videos that i've done if you haven't checked those out check those out as well otherwise that's really it there if you haven't already seen the physics and the chemistry crash courses i will put them up on the screen here and here and you can go and watch those as well get right up to speed all the best with all of the practice questions anyway i will see you guys in the next one [Music] you