OCR A A-level Biology revision livestream

Added: 2026-05-15

[00:00:28]Hi, how are we doing?

[00:00:31]How are we doing?

[00:00:41]You had your AS exam. I got all your Oh, fantastic. That's really good. Your multiple choice questions right. Hi, Alex. How are we? Hello, Kada. How are you? How are we all feeling as we get closer?

[00:01:00]I am good, thank you. I am good. Having a little cup of tea whilst I jump on here to help you guys out. Have we got any topic areas? Excited mostly. Oh, well, that's a good way to be. Excited to get going and excited to get them over.

[00:01:15]Um, I had a question about your progress. Videos are so useful. Oh, I hope you get more successful in life.

[00:01:22]Oh, thank you. I'm really glad they're helping. I'm very good. I am a little bit cold, actually, to be fair. That's why my cup of tea is keeping me warm.

[00:01:33]Um, but apart from that, no, I'm good. I am good. I'm finding that doing these sessions now makes it much easier for me um rather than doing it late in the evening. So in every mock I've done so far recently in bio I've been like two to five marks off an A start in every one. Okay at this point is there a way I can get up to the next boundary? Yes, of course there is. So you are two to five marks off an A star. The one thing I would say is why do you want the A star? you need it for moving to the course you want to do at university or is it just like it's a goal for you that you want to get um to get two to five marks more in the A star I would say to you what is holding you back in the questions that you've done your offer for med is a star a right okay so if it's a case of you have to get an A star and you are slightly off, then what I would say is you need to go back and look at where you're losing the marks. Is it the detail? Is it the um reading of the question? What's holding you back? I think it's mainly exam precision. You know, when they mark papers and do the upwards arrow, I think it means lack of detail.

[00:03:04]You say the upwards arrow. Um I am good.

[00:03:07]Thank you. I'll do whatever topic you guys want. Could you please explain how exactly epistasis and complimentary action changes the phenotypic ratio?

[00:03:19]Right.

[00:03:24]Bullet pointing six markers. Okay.

[00:03:25]Right. Yes. 100%. You won't get marked down as long as it's logical in your answer. Resperometers. Okay. We got some topic areas that people um are asking for. If it's lack of detail, Alex, I would say you need to make sure you're um answers are giving those key terms.

[00:03:46]So, make sure that you are not just memorizing key terms that you're actually putting it in to the right place to be relevant to the question.

[00:03:57]Um, okay. I'm going to start I'm actually going to start with resperometers because I feel like Can we do speciation? Sure. I feel like there's something coming up on respic um and epistasis and also speciation.

[00:04:22]Finally made it to one of my live streams. Yay. Well done. Welcome.

[00:04:26]Welcome, welcome, welcome. Right, I'm going to do a bit of teaching now. So, if I miss your question. I do apologize.

[00:04:31]Obviously, I'm on my YouTube channel displaying as well as on the um Tik Tok.

[00:04:38]So, if you want to join me, come over.

[00:04:40]If you want to just listen, then please stay with me here. Um, but we're going to start with respirometer yourself. So, if you have got, let's say we've got, I'm going to go very basic here. Let's say we've got a yeast solution. So, I'm going to put a yeast solution in here. So here I have my yeast solution and I'm going to look at in that yeast solution giving them different um substrates. So yeast solution which could have moltos, it could have fructose, it could have glucose, it could have starch, it could have sucrose. It really just depends where I want to go with this.

[00:05:44]So, if I have got a yeast solution and I'm going to give them a um respiratory substrate and look at the difference between those respiratory substrates, the first thing if you're ever asked about a question is about planning, think about my independent variable, my dependent variable, my um control variables. And I say this every time. This is like your go-to list. Have I given them independent? Have I given them dependent? Have I talked about at least three control variables? Have I talked about repeats so I can calculate a mean and standard deviation?

[00:06:25]And have I talked about statistical tests?

[00:06:32]Um okay. So if I am doing any type of practical, I need to think about using a respirator. Well, what's going to happen with a resperometer is I'm going to use this and it will be connected to a capillary tube. So they may ask you about knowing the rate of dependent variable, the rate of oxygen consumption. So if it's the rate of oxygen consumption, then I'd be looking at me having a calibrated scale. So here's my capillary tubing and in there I have a colored liquid and we would expect the yeast are going to be respiring and if they are doing um aerobic respiration they'll be taking the oxygen in. as they take the oxygen in that is therefore going to result in them producing carbon dioxide CO2 and that carbon dioxide would therefore potentially be either released back into the air and therefore you're looking at is the bubble going to move and normally if we're looking at this we would expect use the red color the colored liquid to move with the auction going in and we would be looking at the distance it moved and because we're looking at rate we're looking at it over time.

[00:08:08]So we could be looking at the oxygen consumption or we might be looking at the rate of respiration by looking at the distance move because of the carbon dioxide produced by the organism respiring. So yes, it could be either or. And I think they're going to try to trip you up potentially with the um question if they're going to make it confusing. So when you say what is a capillary tube connected to? So this would be a scale and on this would be calibrated.

[00:08:49]So it could be in millimeters.

[00:08:52]So you'd have like little scale here.

[00:08:58]I'm doing this very basic. Okay. So, this is my quick little diagram of it.

[00:09:01]Now, if I'm going to repeat the investigation, I would need a way in which I could have a little tap connected to a syringe and that would therefore be used to recalibrate, put more oxygen in so that it can then push the bubble back to its original position.

[00:09:29]Yes. Now, it's an interesting one. So, if we were looking at the chemical that's going to absorb carbon dioxide, you'd be looking at potassium hydroxide.

[00:09:43]So, it would be looking at potassium hydroxide. Now, what I want to show you, give me one second.

[00:09:49]Um, where are you? Where are you? I'm looking at my study guide for the information.

[00:10:04]Yeah, that's the thing which is what I'm just about to talk about in one second.

[00:10:09]So, be aware that you have to make sure that you are talking about the information that's been given to you in the question. And I've specifically not gone for the usual on purpose. And I've not gone for the usual on purpose because I want to show you how it's about pushing yourself to understand the knowledge. So this one's from my um study guide. So if we were looking at a simple resperter, yes, if we had it with a small respiring organism, whether that is an animal, whether that's a plant, we would want to have either soda lime or potassium hydroxide, and that would absorb the carbon dioxide. But what if we're using a different type and we're not wanting to absorb the carbon dioxide or they give it to you where you're not absorbing the carbon dioxide. So we can still look at the rate of respiration, but we'd be looking at it in a slightly different way. So, one of the things to know about OCR is that they specifically have talked about you knowing, but I've got this back up here about respiration and it being um one second linked to this one here.

[00:11:42]Um it's about the practical investigations into respiration rates in yeast under aerobic and anorobic conditions. So this is one of the things that I would say to you to be aware if they're going to ask questions. it might not be the ones that you're used to with regards to the um soda lime or potassium hydroxide. Now, they love giving a question which shows you the setup like the simple resperter.

[00:12:13]So, it's it's making sure that you've covered all bases and not just that you have memorized the information. So you need to look at what they've given you and what they've asked you in the question to make sure you know how to do this. So if I give you again another one where I show you an actual um question type picture um and of course I can't find it. There we go. So they could give you a picture that looks like, which they have in the past, that looks like this.

[00:13:01]So if they give you a picture that looks like this, then obviously they're expecting you to know how to use the monometer. So it just depends which way they want to go with the question as to what they're going to ask you to talk about in your exam. So if they're asking you to plan the investigation, you need to make sure that it is relevant to the information to the question at hand. Um so how would they trip you up? Like what's the part to know not to get? So what I would say on that one going back to one second this one here as it said in the specification it said about practical investigations in aerobic and anorobic conditions. I have a feeling that anorobic conditions are coming in on this one. So if you are thinking about how would you do this under anorobic conditions now you could potentially talk about the um putting a layer of um oil which would um make it anorobic. You could talk about leaving it for a length of time so that all the oxygen has obviously been used in aerobic respiration.

[00:14:26]And then what you're left with is a um anorobic environment. But how could you monitor that? And this is where they could ask you about improving and talking about using a data logger so that you are able to actually measure the concentration of oxygen or measure the concentration of carbon dioxide. So it really just depends where they feel like they're going to go with this type of question.

[00:14:59]Um, but I do feel like it's either going to be that you have to plan it, and if it's you're having to plan it, you would say that you're going to measure the rate of respiration by measuring potentially the distance moved, which would equate to either the oxygen consumption or the um carbon dioxide being produced, and looking at the difference between the two. The other thing they could talk about is they could talk about well what if you did it with the um organism and you were looking at the oxygen and the carbon dioxide was being absorbed into our potassium hydroxide solution. What could you then do is you could change this. If you're using the monometer, you could change this to have distilled water.

[00:15:56]And that distilled water would need to be of the same volume so that you're not changing the pressure within the um solution. Now, does the oil prevent any oxygen from getting to the yeast cell?

[00:16:12]So the the thing that you have to remember is that the oil would be as a layer of stopping or preventing the diffusion. So you the slow slowing down the process.

[00:16:27]So it's one way in which you can talk about using a um oil layer. But again, you've got to remember that it's they're not expecting you to know everything.

[00:16:38]They're not expecting you to explain it.

[00:16:40]They just want you to think about how you can prevent the movement of substances. So obviously all solutions can dissolve the molecules until they become saturated. So if you have a saturation and then you put a um material on top that is then going to prevent movement of other things basically.

[00:17:06]Um, so it's one of those ones I don't know where the question's going to go.

[00:17:11]Um, but I have a feeling that they're going to give you either a plan and investigation for using a respirator or they're going to give you a set of results because the last time they really did it was in 2020, I think in 2022 where you were actually looking at the respirometry side of things. Um um so yeah, that's where I would go on that one.

[00:17:51]But the key thing is by leaving it for a length of time in a closed system, you are therefore going to assume that the oxygen that was present is going to be used. And that will leave you to a point where you then have um only the carbon dioxide being produced in the um air rather than the oxygen because it's all been used. So I think the leaving it for a length of time is a better one for you describing how you can ensure that it is now um looking at that anorobic um respiration rather than aerobic. Um, one second.

[00:18:39]Um, okay. So, um, that would be what I would say on that one. Um, hold on. They could link this to relative energy values. Yeah, they could link it to energy values, but I I don't feel like they're going to. I feel like they've done a lot on respiratory quotant lately. I feel like but again it's about the difference how could they adapt the questions they've done a lot on respiration and photosynthesis the intricate parts of it so I feel like it's more going to be linked to something else and using it with um biotechnology with the planning of doing the investigation with the resperometer you could even they could even link it to the um using a respirometer and then using a colorimeter. So it really just depends on what question they want. Um, so yeah, so the oil that you would be producing putting there is more about slowing the rate of diffusion down because you're adding an extra layer.

[00:20:00]Um, which is where they could go on that one. Um, how would you measure the carbon dioxide? So this would be about looking at whether or not if we're looking at this one if we've got oxygen that's being absorbed in excuse me oxygen going in carbon dioxide coming out. So if I remove my layer a second, if we think about using the different respiratory substrates, you would potentially expect let's say we were using lipids or we're using proteins as our source rather than it being carbohydrate. So in that case what we could do is we could look at doing it and measuring the difference between the movement of the bubble uh I keep saying the bubble the colored liquid. So here colored this one's a little bit more challenging to do with measuring your carbon dioxide. If you're using a respiratory substrate like um glucose, fructose, moltos, you would expect it to have a respiratory quotient of one. Whereas if we were looking at for example our colorimemetry, we could look at doing a benedict solution and then seeing how much glucose was left.

[00:21:26]depending on where you want to go. With the other one, with this one, it's much easier because you look at with the potassium hydroxide or with distilled water. If there's no absorption of carbon dioxide, the difference in the way in which this h colored liquid has moved would allow you to work out that carbon dioxide concentration. So, there was a question in 2023's AQA exam, which was a really good question on this one.

[00:21:58]I was doing it yesterday with one of my students and let me just get it up a second.

[00:22:15]Let me see if I can find it.

[00:22:24]Here we go. So, this one was a question that we were looking at yesterday and so AQA did it where they gave you investigating the effects of temperature on the rate of aerobic respiration. So, always make sure you're looking at the hints that they've given you when they give you a little bit of the stem of the question up here. Make sure you use that to guide you on how to answer the question. So, we've got the fact that they're saying it's aerobic respiration here. They've told me that they're changing the temperature, and then they've showed me the three-way tap. They've showed me the ruler with a millimeter scale. They've showed me that I've got a diameter. So, I've got a capillary tube here with a diameter of 2.5 mm. And they've told me I've put it in a water bath, which is where I'm going to control when I change that temperature. So, if I was planning this type of investigation, I would want to say about the fact that I could change the temperature in the water bath and give them five values to ensure that that is giving them the um information they're looking for. if that's where the question was going to go. And the other thing to remember as well is whether or not what you're doing with these past papers is fantastic, lots of practice, etc., but you've got to be aware that they're not going to give you the same questions again. So, you have to adapt the question. You have to think about where they could go with it. So here they've changed the effect of temperature on the rate of aerobic respiration and they want to know about control variables that you could have.

[00:24:11]So obviously have your list. So this is what we were doing yesterday. We were talking about temperature, concentration, volume, pH, light, species, number, size. These are like your go-to answers when you have a practical situation, but you have to relate it to the information that is in front of you. So if you're talking about transpiration for example, of course humidity is something you want to mention, but humidity isn't relevant if you're talking about respiration and using a respter. So make sure that you do have your go-to lists. But what I'm finding time and time again is so many students don't seem to actually have a um understanding of how to relate it to the question. They've got their list and they think that list rel relates to every single question. It doesn't and you will lose marking points for saying the wrong stuff. Do you think it's a good it's good to do AQA papers as well?

[00:25:14]I don't think it's that different. It is very good. I bring AQA questions into my OCR sessions because I can see where they will go and OCR is good for AQA students as well if you've done all the questions. However, what you have to be very aware of is the mark schemes are very different. AQA mark schemes are easier I would say to interpret than AQA when it comes to the bulletointed answers. On the flip side, AQA is much harder when it comes to the maths and biology than it is for OCR. So yes, use them. Be aware that there are some differences. There's about 75% overlap.

[00:25:57]So that is really positive. You can use them, but just be a little bit cautious that you are following what OCR want rather than um what AQA want. So there's just some slight differences to be aware of.

[00:26:11]Um, okay. Speciation. Let's do a bit on speciation because I do feel like that's a one. I haven't covered it in a long time.

[00:26:21]Um, and then I'll come back to epistasis because it kind of links um with the bits before. And I'm sorry if I'm missing any of your comments, guys. I am trying to keep on top um of what you're saying. Right, let's look at speciation then. Now, speciation is obviously the production of a new species. Now, how did that new species come around? So, the first thing I would say anytime we're doing speciation, most students obviously link to natural selection, which is great. It is really important to understand natural selection. However, be careful you don't just describe natural selection or on the flip side, be careful that you don't forget about natural selection. So anytime we talk about natural selection, we should always always always give information that helps us to understand what is going on. So if I were looking for example at this question, this is a great question that OCR did and it was talking about Darwin's finches and it was could you go back to the respir resperometer and monometer slide?

[00:27:38]this one. Iman, what what you looking for?

[00:27:44]I'll come back to that when you actually finish your question for me. So, I'm going to continue on this and then I'll come back. So, if we have the Darwin finches, so Darwin's finches, whenever we look at Darwin finches and we're looking at the theory of evolution by natural selection, we should have our key words.

[00:28:06]You are very welcome. We have our key words where we should talk about anything to do with natural selection is about increasing the frequency of characteristics that are best adapted decreasing the frequency of characteristics that lead to changes in the environment. So we have mutations mutations that are spontaneous mutations. So because they're spontaneous mutations, they happen spontaneously completely at random. It is what gives us the variety within the population. So the mutation causes variation. Variation we have lots of production of our offspring. Now the key thing is there will be some form of selective pressure. Now whatever that selective pressure may be that is going to result in you having a characteristic that means you're better adapted or you having a characteristic which means that you are not better adapted and therefore not going to survive. So mutation variation selective pressure survival and then because you can survive you can reproduce because you can reproduce those alos will be passed on. If those alos are passed on, then you would assume that the offspring are also going to possess those alles that are more advantageous. So you'd start to see the frequency within the population for those alles increasing.

[00:29:42]So that is what whenever we talk about natural selection. So when we talk about speciation that comes from the cyclic nature of natural selection, natural selection happening again and again and again and that will therefore allow for changes to happen. Um could you link that to genetic drift and gene flow? You could if you are, but be careful when you talk about genetic drift, you talk about gene flow, you talk about founder effect, you have to make sure that it's important that you are relating it to the um information. Guys, give me one second. I will be back.

[00:30:38]Hi there. Thank you.

[00:31:02]If you didn't know I was live, you definitely do now. Uh, okay. So, where were we on this one? So, we were talking about that founder effect, the genetic drift, the gene flow, and talking about natural selection. So, make sure it is relevant to the question that's being asked. So if you're going to talk about the founder effect when we go back to the land masses being as one we obviously had pangia pangia then plate tectonics we have the division we end up with their islands. So they were common ancestors in the last place all together and then those land masses moved and as they moved we are then going to have a decrease in the number of individuals.

[00:31:51]And so if we're decreasing the number of individuals, we're potentially decreasing the gene pool that is available. So when we talk about the gene flow, we need to be aware of how those genes can flow from one population to another.

[00:32:10]So if we're looking at this question specifically, this one was looking at you understanding the different types of natural selection and knowing about the disruptive and knowing about the um it actually spoke about disruptive and it it gave it to you. Whereas in your actual specification, you only need to know about stabilizing and directional.

[00:32:38]So there's two you should know, stabilizing and directional.

[00:32:46]So when we're looking at stabilizing and directional um selection, what we're talking about is if we're stabilizing, we're expecting the average the bit in between the stabilizing selection. Our graph should show us one peak and the two extremes being very low. So with stabilizing we could in a sense say that the birds that were here with regards to the finches the beak size they have stabilizing selection in the fact that they have one peak which is at the minus 1.8. So we can see stabilizing selection here. Now directional selection would be that one of the extremes is selected for. Now that could be either of the extremes being selected for. And so what we get in this case, this other organism I would say shows very clearly a directional selection in the fact that the highest beak sizes is actually towards the minus2 between minus2 and 0.2. So I would say it's between here is where we have more of them. So therefore it is directional is stabilizing when the mean is select.

[00:34:23]Yes. So stabilizing would be where the mean for the population is selected for and you'd expect those two extremes to be selected against. So the numbers it's not that there would be none. It's that the numbers would be low in comparison.

[00:34:40]And so you're looking for is there one peak and is that peak in the um middle around the mean or is there a directional selection and if there's a directional selection is that because actually it's moving that there was a lot of variation and that variation is changing because the selective pressures are changing.

[00:35:08]Why did the question suggest it could be disruptive? So, this was a really interesting question because this question was actually looking at them telling you that disruptive selection which you don't need to know about although it is important to know. So, disruptive is where you have that the two extremes now are selected for and they it was a rubbish graph to be honest on this one. They tried to say that that was the second peak there, that there were two peaks, but there weren't. There was only one real peak. And so sometimes when they give you these questions, they're trying to see, do you know and can you pull out of the information in the question. So it's not on the spec.

[00:35:58]It is in the textbooks. it it did tell you in the stem of the question though that it was two extremes that were selected for. So if it's two, you would be expecting there to be two peaks. No, disruptive is not the same as directional. Directional is that one extreme is more advantageous than the other. If I take these away, when we say about the directional, we're saying that the population frequency of this characteristic is changing whatever way it's changing. So it could have been that there were higher numbers here in the past. So it could have been that there were higher numbers here in the past, but what's happened is those numbers are dropping down because they're not as advantageous. It is better for you to have characteristics of a beak size between 0.2 and two. Now, this could be because it was something I used to have to teach when I was teaching the IB and we taught about the El Nino and um El Nina and it was about the changes in the environmental um situation. So whether there was like lots of rain or whether there was lots of drought and how that affected the seeds affected the fruits affected the um food availability. And if that affected the food availability then those birds the finches that had the correct beaks and the beak depth to be able to deal with the food sources are going to survive. And if they don't have the right uh bead beak depth, they're not going to be able to get the um food, they're obviously going to die. If they're going to die, they're not going to reproduce. Their alias won't be passed on. So you'll see a change in the frequency of the characteristics based on changes in the environment. And that's how you have to remember that natural selection is to do with the selective pressure. Whereas when we talk about the bottlenecking the changes in the frequency of the alios is to do with by chance some event has happened which has decreased the number. Now this hasn't told you about speciation yet. I am going to lead into that. But what I'm trying to get you to see is that you have to remember all the other parts of the topic and how they link together.

[00:38:36]It's not this topic stands alone to that topic to that. It's they're all interconnected in biology. And if you can understand that and see the bigger picture, you can then apply this to whatever question they give you.

[00:38:54]Oh, I hate code tea.

[00:38:56]I talked for far too too long. Right.

[00:39:00]Let's go back to speciation though. So we know about the fact that we have got our um natural selection occurring obviously and that natural selection occurring.

[00:39:17]Um at the moment I'm just doing general revision based on what people are asking me to do. That's what I do in my free lives. I have got some videos out there on kind of my predictions slash guesses.

[00:39:29]Um, however, what I would say to you is, um, I do obviously I've analyzed and I've looked at the papers and whatnot, but I don't know who wrote these papers. I don't know what's going to come up. I can't guarantee to you that this is definitely going to be something that they cover.

[00:39:49]So, I would say to you, try not to get too hung up on what the predictions are and try to focus on filling any gaps.

[00:39:58]The reason I do these sessions so people can ask the questions and try to really get that depth of knowledge so that any question you do get asked, you can then try and apply the knowledge that I've hopefully instilled in you. But yeah, it is hard. It's hard because I know you guys want a quick fix and I know you want to go into that exam as best prepared, but nobody knows apart from the person who actually made the um paper. And so it's important that you don't just focus on studying the stuff that you know. It's that you focus on the stuff you don't know and you find those gaps and you fill them because if they ask you a question about the stuff you don't know and you have studied a lot on what someone's predicted that is going to make a big difference for you.

[00:40:50]Um it's better to revisit everything because they all honestly paper two comes in so much when you're doing your revision for module five I say paper two module two when you do your revision for module five and module six if you're not bringing through module two three and four you're not revising properly for biology.

[00:41:11]Um when do you usually do your lives? So I do my lives now on a Wednesday at 11 o'clock um to help you guys out. I used to do it in the evenings. Um, but I'm doing it during the day now. Oh, no. I didn't mean to do that. Sorry. I have no idea. Hi, I just hit the wrong button.

[00:41:30]Someone's just joined me on here. Sorry.

[00:41:32]Um, I'm going to actually I don't even know how to stop that.

[00:41:36]Um, I am from Cambridge and I am um doing a live on YouTube. So, I'm actually going to stop you. I'm so sorry.

[00:41:46]Sorry, guys. I have no idea what I just did there. tried to cancel and I accepted. I'm going to jump back on.

[00:41:53]That's hilarious.

[00:41:55]You can tell I'm not used to doing the whole um Tik Tok stuff. Right, back to this speciation. Speciation is this formation of a new species through the process of evolution. So, what is evolution? Evolution, and this is what you have to remind yourself, evolution is this cumulative change. So all of these changes being added up over time and it's those changes which are in these inherited characteristics within a population. So natural selection obviously was us looking at our mutations, our variations, the um selective pressure, survival, reproduction and the um alos being passed on. Evolution is about these adding up of these changes that are happening over time and the population evolving for having better features that are going to help them to survive in the changing environment. Whereas you've got to remember that because we've evolved in one direction doesn't mean we're not going to evolve in the opposite direction. if that is where the selective pressures are navigating us to go. Okay. So the formation of a new species through this process of evolution through this process of changes. So when we try and have these individuals mate and they are inbreeding so interbreeding if they're interbreeding are they able to produce fertile offspring? If they cannot interbreed and produce fertile offspring, we would then classify them as a new species. So how do we actually get this formation of a new species?

[00:43:50]Yes, evolution is 100% linked um with speciation. So that formation of that new species happened because of evolution because there were these accumulation of changes that when we try to bring them back together they're not able to interbreed and if they're not able to interbreed therefore we have that they are now potentially a new species. So the first thing we have to understand is the difference between them being isolated so that they can't interbreed and the fact of when we bring them back together them not being able to interbreed. So there's two ways to look at this. The first thing is what has happened to separate the populations and that separation has to happen through some form of isolating mechanism. So we are going to isolate these populations and when we isolate these populations because we have isolated them they are no longer able to integrate therefore there is going to be no gene flow between those two populations.

[00:45:06]So there are different ways in which speciation can happen and the first part is how did they get isolated? Did they get isolated by some form of geographical isolation?

[00:45:20]So what we mean by that is the populations are geographically isolated that they're going to occupy different environments. So is that a case of there is a mountain, a river, sea? What has happened to cause them to be isolated?

[00:45:40]So if they are isolated in the fact that they are now in different environments and it's a geographical isolation then that is called alopatric speciation. Do you have to know the four types of no so the four types of temporal mechanical behavioral and reproductive isolation? No, you don't need to know that for OCR. However, it does help to understand the fact that that is more sympatric speciation, not alopatric speciation. So, alopatric speciation is that they are geographically isolated. They're in different environments. Whereas, if we were looking at sympatric speciation, this would occur where they are reproductively isolated within the same habitat. So when we talk about temporal, we're talking about the fact of them being able to they're in the same environment yet, for example, they become reproductively active at different times. And because they're reproductively active at different times, there is no gene flow. They are not breeding at the same time. They get to the point where they're completely isolated because they are reproductively active at different times within the year. If we're looking at mechanical isolation, obviously they don't have the right parts. They're not compatible.

[00:47:08]There's no way in which their gametes are going to be able to come together.

[00:47:14]So alopatric speciation is about that geographical different environments whereas sympatric they're in the same habitat but they are reproductively isolated.

[00:47:27]So what reproductively isolated them to begin with is whether it's alopatric or sympatric but as we get on to that formation of a new species they then are completely reproductively isolated.

[00:47:41]Um so we tend to talk about it being really common in plants because obviously they can form hybrids. So when we do meiosis, we take our diploloyid individuals and when we are getting to that end stage of producing the gametes, we end up with hloid individuals. So if we have for example these closely related species, what can happen is you can get hybrids. So if you get hybrids, these hybrids are no longer able to reproduce with the parents. However, what can happen is more hybrids can be produced. And so that is how we actually got our modernday wheat is because they became reproductively isolated. The hybrid that was produced wasn't able to reproduce with the originals but is able to reproduce with uh more of itself or self-rerodction. This is the thing about plants. Plants can do cross-pollination or they can do self-pollination, which is how they are very different to us.

[00:48:51]And I'm not going to go into the plant side of reproductive bits because you don't need to know that. A hybrid is where you have a mix of the two. So, if I were to try and take a um horse and a donkey and I were to mate them, I would produce a hybrid, a mule. But that mule is actually um infertile, it's not able to produce a fertile offspring.

[00:49:22]Therefore, we have a horse and a donkey in which they are different um different species. So the mule would be the hybrid of the two. And the thing is with animals they are infertile whereas with plants they are fertile and can therefore keep going with the reproductive side of things. And so when you get a hybrid which is a mix and if I had like a lion and um a hold I'm trying to think about this one. A lion and a tiger. You'd get a I think it's called a liger. Anyway, a hybrid is a mix of the two. I can't remember what they're called on top of my head and because I'm doing this live, I'm like my brain don't go down that route because I can't remember. But yeah, how long are you um live for? Um I'll maybe do about another 15 to 20 minutes. Um so offspring have to be fertile. If they are not fertile, then you would say they're different species.

[00:50:21]Yes. And that would be how we could identify that we have um a different species if we were going to classify them. It is a liger. Thank you. There we go. What's the other one? There's like so many other ones. I used to teach this that part of it like such a long time and I knew so many of them. Um but now it's like oh I can't remember. Anyway, moving on. So just to remind ourselves what is speciation? So speciation, let me move that down slightly is this formation of the new species through that process of evol evolution. So the first thing we've got is isolation. So that isolation happens. Now is that isolation because of it being um alopatric they were geographically isolated or is it because of satric and if it's because of sympatric it is that they are reproductively isolated within the same habitat. So in this one they're in the same habitat. In this one, they would be in different environments.

[00:51:38]Um, and so therefore, we have some form of isolation that's happened. Then whilst they're in their different environments or whilst they're in the same habitat, we have got random mutations that are happening. So random mutations occur.

[00:51:57]Those random mutations cause variation.

[00:52:01]Variation means that there'll be some form of selective pressure. That selective pressure is going to result in the selected for and the selected against. So are they are so after they are isolated does a mutation occur?

[00:52:21]Mutations are happening all the time.

[00:52:22]This is the thing. It's not a case of after. It's that they're always happening. And so because they're always happening, it is about the fact that some are selected for, some are selected against, some are silent. Some mutations that happen are silent. We don't see the changes. Um, and so therefore, you've got to really look at what the information is in the question. And that's where students get caught up in, oh, so it's this, then this, then this, then this.

[00:52:54]It's about can you talk about what it is. So let's say it's behavioral.

[00:52:59]No, the selective pressures are different. So is the selective pressure in the fact that the temperature has changed? Is a selective pressure the fact that they are not getting chosen for the mate to be a mate because they don't have the right behavioral response? Do they have the wrong dance?

[00:53:17]Do they have um I love this whenever I've taught about behavioral um mating.

[00:53:23]When I do GCSE, I talk about the fact that you get these um different organisms that do things in a specific way like the bower birds and you have the birds that like waggle their heads and if they waggle their head, if they don't do it the right way, they're not selected for. Or what if they have the wrong bird song and they're not selected for? What if they don't have the right like spiders that headbutt and if they don't headbutt in the right way, the um mating um chooser in a sense is going, "Oh, you you're a bit strange. You're not the one I want to go with." And so therefore that can cause the um selective pressures being about having the right mating, the right environment, the if you're a penguin, you've got the right pebble or the biggest pebble or whatever that may be. So there is something that is causing them to be isolated.

[00:54:17]Um and so it really just depends on what that selective pressure is. But that selective pressure is going to result in the selection for characteristics and the selection against characteristics.

[00:54:29]So even in the same habitat absolutely.

[00:54:32]So if it's sympatric it's within the same habitat. If it's alopatric it's in different environments. So therefore once you have these selective pressures you're going to see these changes in these alio frequencies and that happens over many generations. It doesn't happen automatically. It's over many generations and that will lead to these changes in the phenotype. And I love, it sounds ridiculous, but with when my girls were little and we were looking at the smids and the smooths or there was another program about the hearts and the stars um and these um kids programs, they're basically trying to show you these different species, but these species that have come from potentially an ancestor that was um a common ancestor that led to them. But the fact in the sense and the smooth they can produce a baby, that baby being the purple one, I'm like, is it fertile or not? Because if it's not fertile, you are different species. Or were you a different subspecies because you actually produce a fertile offspring?

[00:55:35]The weird things that I think about when it comes to biology when I'm watching these kids programs is just bizarre.

[00:55:41]Anyway, so we have this change in the alio frequency over many generations leading to those changes in the phenotype. that if I bring these organisms back together and they can mate and they can interbreed, they can produce fertile offspring, they are the same species. So sometimes we have it the organisms have been um classified as being different species and then actually when we've looked at them, when we brought them back together, we realized we made a mistake. We need to rearrange that classification system.

[00:56:15]And this is where they could bring in your um tax on. So kingdom film class order family genus species. They could end up reclassifying and they did that with plants where they had them in um different families and then they realized, oh actually there were so many similarities we need to come back. But they looked at these characteristics, these phenotypes and they were like oh but they're so different. Therefore, they have to be in different families when actually they realize they shouldn't have done that and they brought them back. But again, that's not something you guys have to worry about. If they do give it to you though, it will be all there in the question to help you. But the key thing is if we are interbreeding them, they are no longer able to interbreed. They are now reproductively isolated. So we have the formation of the new species which was through the process of speciation alopatric or sympatric speciation. So that formation of a new species in the same environment or in different environments and they've done lots of things where they've given you questions which talk about um so they have the same niche or they have different niches and if they have the same niche that would give you evidence for sympatric speciation.

[00:57:45]So inbreeding and interbreeding is where you are um interbreeding within the population. So you've got lots of gene pool um lots of alles and so therefore you would find lots of um variation when you're inbreeding. If you inbreed you would be going to that homozygous um recessive traits more or homozygous dominant traits more. So by inbreeding you are limiting the gene pool.

[00:58:17]Interbreeding there's lots of variation out there. So inbreeding is about you selecting only those with specific traits being able to breed. therefore causing more um genetic disorders to be prevalent within if we're talking about dogs for example. Um so the niche is to do with the lifestyle and the environment. Um so when we talk about the niche, we're talking about where we find them and how they interact. So their lifestyle, what do they eat, what kind of things, where are they located?

[00:58:59]So that's the the name that we give it that their niche is all of it encompassed in one if that makes sense.

[00:59:07]Um right I did see that you asked again hold on one second about I don't know if you're still here. Um where did it go?

[00:59:22]Epistasis. You did ask it again. Anyway, epistasis and the do we need to know the definition of a niche? No, but you can use it as an answer. Um, right. Declined. uh you can use it as the answer if they give so they gave a question about it a couple of years ago which was about the protocas and the kacas and the fact that one could fly and one couldn't fly but they were found in the north and they're also found in the south and d so yes so the lifestyle diet and roles of the species absolutely um thank you um cadia right okay epistasis what is epistasis well epistasis is is where you're looking at. So if we were to look at our chromosomes and we had our let's call this chromosome number one and chromosome number one has our gene A on it and we're going to look at and I'm doing this very basic by the way chromosome number two and chromosome number two has got gene B on it. If I have epistasis what I'm talking about is the interaction of genes. So gene B could interact with the expression of gene A. So gene B could actually inhibit the expression of gene A. So if gene B is present, if I have a capital B, I would therefore prevent the expression of gene A whatever gene A may be. So even if I have capital A capital A or capital A lowerase A, if I have a individual that has the dominant alo and that dominant alo could be I don't know that you would have um purple flowers.

[01:01:29]So if I have a dominant alo for purple flowers but the person has got either capital B or capital B lowerase B that results in no pigmentation.

[01:01:44]Therefore, even though you have got the alles for the dominant trait because you don't have the um lowercase B's then you don't you are inhibiting the expression of gene A. So it could be so B could be for exactly a transcription factor.

[01:02:13]It could be for a um so it could be a transcription factor and remember transcription factors can be ones that inhibit or can be ones that promote transcription.

[01:02:26]So it could be one of one of two things.

[01:02:30]Don't just assume that transcription factors always inhibit. They can inhibit or they can promote it. um it could be for a repressor protein.

[01:02:42]For example, if you were looking at the lac operon example and you talked about the regulatory I gene and how the regulatory I gene codes for this repressor protein. So having this gene, this gene could code for a repressor protein. We could have the fact that it could code for a um nonfunctional functional um enzyme that's needed in the production of the pigment. It really just depends on where they want to go with the question. So the fact that we have these genes that are going to um be interacting with the expression of another gene then we say that that is epistasis.

[01:03:34]Um no repressor proteins aren't only for proariots. They will allow it for the ukariots as an example. However, they really want you to talk about the transcription factors rather than um the repressor proteins because as we understand more about ukareotic organisms, we understand it's a little bit more complicated. Why? Because our chromosomes have the DNA associated with the histone proteins.

[01:04:09]And because the DNA is associated with histone proteins, it means it's more complex and therefore it's more to do with those transcription factors.

[01:04:28]So that's an interesting question. It's one of those ones where I'm like, it's been a while since I've even looked at the other parts.

[01:04:48]So, what do you mean by a hypo um hypoatic one gene being hypoatic Z?

[01:04:54]That's where I don't actually um know that definition. So then I'm like it's uh important for me to look it up to be like hold on a second.

[01:05:11]Ah so yes so that would be class as the one where the effect is masked by another gene in the interaction. So yes, is this do? Yes, this would be dominant epistasis because I've said it's the capital um letter. So therefore, it would be dominant epistasis. And if I'd said it was the lower case, then that would be recessive epistasis.

[01:05:40]Yeah. So yeah, it is. But this is the thing. You have to remember that as teachers and the things that we teach, we don't always know it all. We don't remember all of it. And so, actually, when you ask a question like that, your teacher might go, "Oo, I'm not sure."

[01:05:56]And that's what I did. I was like, "Let me think about that one. I'm not entirely sure, but I can go and do the research just like you can." If you're not sure about something in the topic area, then you should be going and looking up, not just going, "Oh, I don't know it." because that's going to be the difference of you being able to access um the content or not. When you don't understand what's going on, go and look it up. Go and figure it out. Um right, what was the next topic here? I'm kind of lost on where we're at.

[01:06:40]The comi, are you still here?

[01:06:44]If you are, can you explain to me what you mean by complimentary action? Are you talking about the um enzymes?

[01:06:56]Are you talking about the nucleotides being comp what do you mean by complimentary action?

[01:07:06]But what do you mean by that complimentary action of what?

[01:07:14]Next one was hCG an antibbody in pregnancy pregnancy thing. Yes. So how to use the how it produces a 9 to7 ratio.

[01:07:27]Oh okay. So let me just do this one quickly. So when you look at the dominant epistasis or recessive epistasis, so when you're looking at la one second um is it this one or is it this one? The numbers that you produce. Let me do a quicking of No, it's not that one. It's not that one.

[01:08:03]when you're looking at epistasis and you're looking at how go things come together and your phenotypic ratio. So obviously if we have two heterrozygous individuals that are going to be crossed together here we go. So if we're looking at epistasis in this interaction and we're going to cross them together. If we're looking at dominant epistasis, just move things around and we were to produce a punet diagram. I've got ga, I've got dominant and recessive. I've got dominant, I've got recessive. And therefore, if I cross two heterrozygous individuals, I would expect a 9-3 to 3:1 ratio. So because of independent assortment I would expect there to be that 93 to 3:1 ratio and therefore when they come down and come across blah blah blah blah blah once we filled in the diagram what we then get is obviously if dominant A is present there's no pigment whatsoever. So in this case, because I've got dominant A in all of these, and what I would suggest is as you're going through, the minute you see at least one dominant A, you identify that that dominant A being present is going to result in no pigment whatsoever. And so therefore, that would give me a 93 to 3:1 ratio. Now if I were to do a test cross with regards to um checking whether one is hetererozygous or whether it's do dominant I would expect there to be a one one ratio. So a test cross would get should give me a 1 one ratio. Whereas if I'm doing hetro versus hetro I would should get a 93 to 3:1 ratio. But if I have dominant epistasis as you can see I've got a completely different phenotypic ratio. And so therefore in this one I would get a 12 to 3:1.

[01:10:16]So if I am crossing with a homozygous parent, I would expect a one one to one to one. But if it's epistatic, it's not going to give me that. And if I were looking at for potentially the recessive color being white, I would then say that instead of the green there, that would come under and it'd be 13 to three. So that would be one of the ways. And if I was looking at it as being the um recessive traits again going through fill it in and again you get a different um phenotypic ratio because you have got the recessive alles and therefore if I've got the recessive alles I know that that prevents the pigment from excuse me being deposited. So it really just depends on the example that they give it to you.

[01:11:12]Is 12 to 3:1 in heterrozygous.

[01:11:15]Yes, that would but no that was dominant. Um yes, heterrozygous parents being crossed and with a dominant epistasis. Recessive epistasis gives you the nine to three to four.

[01:11:32]Does that help?

[01:11:34]Um right so it was about hCG and pregnancy. So next one then if we talk about how would you get a 9-to- 7 ratio?

[01:11:47]So the 9-7 ratio would why do you get a 13 to1? So 13 to1 was me saying that if the recessive trait were white for example. So in this case, the recessive trait is green.

[01:12:06]Whereas if that recessive trait was white, that would give me 13 whites.

[01:12:13]So that's how I would get a 13. But I wouldn't get a 13 to one. I'd get a 13 to three. 13 whites to three oranges.

[01:12:30]Jidima, you just joined us and then go, I want to talk about this, which I've literally just finished. Sorry, you just missed that one. Um, okay. What are we doing now? We're doing hCG, right? So, hCG, um, human corionic gonadotrophen is a hormone. Don't freak out. You don't need to know that. HCG is a hormone that when someone is, um, pregnant, they are going to produce hCG.

[01:12:57]So, hCG is a hormone that is produced when the embryo embeds in the lining of the uterus. It's a little bit more information you need to know, but I'm going to tell you that anyway. So, hCG is this hormone that is going to be produced by the embryo when it embeds in the lining of the uterus. It's all right, Chidima.

[01:13:22]It's fine because you can watch it back.

[01:13:24]Um so yeah it was just if you rewind a little bit back you'll be able to see uh what we were talking about. So the hCG what happens is when the embryo embeds in the lining of the uterus it will then produce hCG which stops the ovary which has ovulated. Again I'm going into way more detail than it needs to go into here but sometimes I find that that helps. So what should happen is when the egg is released during ovulation, what happens is the follicle that was containing it will actually form a corpus litium. A corpus litium is an empty follicle and that empty follicle is what is going to produce progesterone. So what happens is this produces the hormone progesterone and that progesterone is going to maintain again I'm going into way more detail uh maintain the lining. Now if there is no embryo embedded in the lining of the uterus that corpus litium is going to degradate. It's going to um break down and no longer need to be active. It's no longer going to be producing progesterone. So therefore that is going to um basically be destroyed for a better way of putting that. Now if there is an embryo embedded in the lining of the uterus we want to maintain the lining of the uterus. So the embryo produces hCG and the hCG causes the corpus lutium to remain. It causes it to stay there to keep making progesterone as the embryo develops into the fetus and the fetus continues until it's born. So this is the point in if there is an embedded embryo in the lining of the uterus that is going to produce hCG. That hCG is then going to be circulating round. And what happens is when we do ultrailtration in the kidneys, that hCG is going to go into our um nephrons and that is then going to go into our bladder and it will be secreted in our urine. So just to get you to understand how it all interlinks. So if you are pregnant, your embryo has embedded in the lining of the uterus that therefore produces the hCG so that it can maintain the pregnancy and that hCG that hormone is going to be filtered out ultrailtration which means it is small enough. It is small enough to get through the basement membrane and the picosytes at the bulman's capsule and the glomemeulus to get into the nephron.

[01:16:17]It then goes into the urine and we excrete it. So when we look at a pregnancy test what we have to understand is that hcg is a molecule.

[01:16:31]So hcg is a molecule a hormone which has a shape to it. So this structure of the hormone is going to be complementaryary to a receptor and if it is complementaryary to a receptor it can bind together with the receptor and therefore that can be responded to. So if we understand that we can use what's known as monoconal antibodies. So we have got and I'm going to do this very basic just to be make this easy monoconal antibbody. So this is a really dodgy picture. Um this is what a monoconal what am I doing? Why am I doing it like this? Why am I not just getting up my lovely pictures that I've got in my study guide? This is the thing. I'm like oh yeah I'll just do it freehand. And I'm like, "No, just get my pictures."

[01:17:30]Uh, my excretion, isn't it? It's my excretion topic area. Let me bring my nice little um diagram across rather than me do a dodgy thing. Uh la.

[01:17:45]Here we go.

[01:17:50]Here's ones I prepared earlier.

[01:17:54]Way better than what I just drew. Okay.

[01:17:56]So what have we got? We have got if I make this bit bigger.

[01:18:07]There we go. So what do you do right if I have gone to the toilet and I have my little cup and my little cup is filled up with the urine that I am going to test. So, here we have my urine sample and my urine sample. What I'm going to do is I'm going to take my pregnancy test and I'm going to place it into the um sample and what's going to happen is capillary action is going to cause it to move up through the pregnancy test. So the urine is going to move up through the pregnancy test by capillary action.

[01:18:54]Now inside the area, the little bit that you're going to dip into the urine, what you actually have is you have free monoconal antibodies. So this is my monoconal antibbody which is free and it has a dye attached to it. So you're absolutely right. you're going to form a hCG antibbody complex if you have a um hCG present. But what you have to understand is in this diagram this monoconal antibbody is also going to be able to bind to a antibbody which has been fixed. So this has been fixed into position. So I have this antibbody a monoconal antibbody of non complimentary shape which is fixed in position. I have this one which is a monoconal antibbody which is fixed to the test site. So if I have hcg in this case this is my hcg molecule.

[01:20:03]If I have HCG in my urine sample, it will bind to the free monocone antibodies. So these ones were originally free and they were located in the site that is going to be used and put into the urine.

[01:20:33]So I'll come back to what a monoconal antibbody is. So they were free originally in the site where we're going to put the tip into our urine sample.

[01:20:45]And so what happens is because of capillary action they are going to make their way up through the pregnancy test. And as they make their way up through what you will have is you'll have these free let's not say free these fixed that's what I mean fixed monocchonal antibodies which are complementaryary to the molecule. So this fixed or I could also call this immobilized.

[01:21:22]So this is where your immobilized enzymes come in. So I have an immobilized a fixed monoconal antibbody at the test site and that one is complementaryary to hcg.

[01:21:37]I have another immobilized fixed monoconal antibbody which is in the control site and that one is going to bind only with the free monoconal antibodies. So if I have no hCG, so hCG is not present, there's nothing to bind at the test site, the window will stay clear. The control site, what will happen is those free monoconal antibodies as they made their way up through capillary action, what's going to happen is they are then going to bind to that immobilized antibbody. And when they bind that is going to form as it's been said already a an antibbody complex and when that antibbody complex has been activated that therefore activates the production of the dye. So you can see here the dye and you get a stripe. Now when there is hCG present the HCG will obviously bind to the complimentary antibbody and so therefore because we have the complimentary antibodies it is binding in the position. Now some tests they will put the fixed ones in a cross other tests they'll put the fixed ones in two lines. It really just depends on the test and what they're using. So the key thing is we are using these monoconal antibodies because we have these monoconal antibodies which have a binding site that is specific to the chemical that they are going to bind to.

[01:23:20]And so therefore if it is specific to that chemical it will allow for the binding because of their complimentary shapes and because of that it is going to stick in that position. when it sticks in that position that activates an enzyme um complex which therefore results in the dye being produced.

[01:23:44]Um okay so what have I missed? Uh so does it attach to the control site first and then the test site? So no it wouldn't it would it should bind to the test site first and the control site afterwards. And the reason being is because the control site is always after. If you think about that capillary action, my test site should be here. My control site should be back here. So the control site is always afterwards because you want to see the first um part first if it's the same hormone. Why are they different? The control site is your way of testing that the test is working. So they are different antibodies that have been monoconal antibodies that have been fixed to the position because your control site is to prove that the test is actually functioning properly. If you were to get a positive result at the um test site, let's say I get a positive result here and I don't get anything at my control. That was my control. That would be classed as a negative test. Um, so this my test site because the fact that I haven't got a um a reaction. I was trying to think of what the word was there. Because I haven't got a reaction at my control site, it means it's a faulty test and so I would have to redo it again.

[01:25:21]The other thing you have to note is that you have to be careful um with regards to the timing with pregnancy tests as well because pregnancy pregnancy tests actually only have a very short window.

[01:25:34]So there's a a three minute wait that you do and then after those three minutes you could end up with a positive result later on coming up and that positive result could be because of a um evaporation line. Um and so therefore you have to be very careful that you are understanding that there is a time frame to do this in and not going back and looking. Although saying that, funnily enough, when I first got pregnant with my first child, um, my eldest, when I took the pregnancy test to begin with, the pregnancy test came up negative. And then because I was a bit obsessive and I was like, something's not right. And I looked later on, it came dark and I was like, oo, am I actually pregnant? And then I took a test again the next day and that came up really clear. And you have to remember that the concentration of the hCG. So when you actually take the test will be affected by the concentration within the urine. So they always say if you were doing a pregnancy test, ideally with if you're early on in your pregnancy because your hCG concentration is so low, you would want to do it in the morning rather than in the evening because throughout the day you are drinking lots of fluid, therefore producing a diluted urine sample. Whereas in the evening, because you're not drinking, your body is reabsorbing the water back. Oh, that could be a really good question. The water is being reabsorbed back into the bloodstream throughout the evening. And so therefore, in the morning, the hCG concentration is really concentrated.

[01:27:28]Um, I mean, advantages and disadvantages for this test method.

[01:27:36]What's the advantages of it? The advantages of it is that it's a quick quick test. It's the same as if you use the COVID testing for the presence of an antigen. That was using the same principles. Um so yeah, they could go down the positives and the um negative.

[01:27:53]So yes, advantages. It's a quick and easy way of testing for something.

[01:28:00]Negatives, it could give false positives. it could give h false negatives. Um, so I don't feel like you need to memorize things on that front, but I do think it's good to think about those positives and negatives because yes, it could come up.

[01:28:17]Guys, I am going to finish there because I have been doing an hour and a half and I really need to now. I've talked about so much urine. I need to go to the um ladies room and um excrete the ura nitrogenous waste and excess water and salts. Um so I'm going to go and thank you so much for joining me. If you have your exams because I know exams have all started. Well done. Um keep going. Good luck. Um, for those of you obviously who are only doing your chemistry, biology, and math, oh, you've still got a couple of weeks and then it's a very heavy week, uh, like a very heavy three weeks.

[01:28:56]So, keep going. Make sure you are doing all of your subjects and also you're doing all three um, practice papers.

[01:29:04]Don't just focus on one. Guys, thank you for joining me. Please do keep liking, sharing, commenting. I really appreciate it. And if you know any year twelves um who are looking for support are are struggling, please do send them um to my resources because I want to help as many people as I can. And if I don't see you again, if you don't join me for um another live, then good luck with the exams. Um try to think about the holistic view of biology and the bigger picture. Everything is interlin. So I've just been talking about monoconal antibodies. You should know about the antibbody structure and the complimentary side of it because of the uh module 4 knowledge. So this is where it all interlinks. Um I will do a live next Wednesday again. Yes, I won't do a live on the halft term week because I'm doing my course. Um so I will go live again next Wednesday um at the same time. And then my plan is when I'm not doing one-to-one tutoring or my group sessions, I'll try and go live as much as I can before the exams. But obviously my private tuties are taking priority because that's how I make my money.

[01:30:22]Basically, I don't make my money through doing this, but I want to help you guys as much as I can. Um, yes, all my lives are posted on my channel if you want to watch afterwards. Absolutely. And if you actually want to watch any of my lives that I did last year as well, they are there in the playlist of lives. So last year I did a whole load of lives just before the students went into their exams and you can watch those as well.

[01:30:46]The content is still relevant even though it was around my predictions for last year's exam. There were things that I predicted last year that didn't come up yet. So I feel like they're going to come up this year. So, some of the stuff that I've spoke about in those lives will still be very relevant and also all of it's relevant to be honest because who knows where they're going to go. But guys, I am going to go. So, thank you for joining me. Have a