How can you best prepare for writing the essay for the AQA Alevel biology 2025? Well, I'm going to be going through with you three key titles that we can prepare together. Hi everyone and welcome to Miss Estri Biology and we are going to be going through three titles for the essay today. And if you weren't aware, the essay is worth nearly 10% of your entire Alevel grade. So, if you can crack writing this essay, it is such a good opportunity to boost your grade up. Now, I've been teaching for 16 years, and I do so much past paper analysis. And I've been analyzing every single essay that has ever come up on the new specification, plus the old specification as well. looking at things like which titles get repeated or similar versions of which year they last came up in, what is the gap between repeats and so many other little bits of algorithm to try and come up with what would be some good essay titles to plan this year to best prepare for 2025 set of exams. Now, this does not mean I am predicting that these are the essay titles that are coming up. I think it's really important to make it clear these are not predictions because as soon as people hear predictions sometimes they think they can just learn those essay titles they're definitely coming up and that's all they need to do for revision and obviously that's not the case. This is based on past paper analysis not predictions. It might be something similar, it might not. So you should plan these essay titles but also do general essay preparation as well so you don't set yourself up potentially to fail if something different comes up. Having said that, I do recommend you do plan these because based on my previous analysis in 2022, the essay that we planned in the live the night before the exam was the essay title that came up. In my 2023 YouTube video version of this, I had three essay titles to plan. The two that came up were two out of those three. And in 2024, in one of my videos like this, I suggested looking at carbon compounds and we planned that essay. It actually was phosphorus compounds, but you could pretty much use the exact same essay plan that we did, but focus on the phosphorus in the compound instead of the carbon. So, 2025, let's see. It might be something similar to what we go through in this video and the part two one coming up. But these are not predictions. Yes, plan them, but also do other preparations. I do not have a crystal ball. So, that is my massive disclaimer. Please do not just learn these essays. You need to make sure you are preparing for essays in general. Now, there is going to be a part one and a part two to this video, but if you want even more help preparing for the essays, I have two really, really effective resources that students have used in years previously and found them incredibly helpful. Number one, I have a self-guided essay online course. It's a miniourse. It goes through everything you need to know to write the essay taught by me in recorded videos, but you also get a model essay with it. You get beyond spec paragraphs. You get topics you can apply to any paragraph plus some other little resources to help you write your essay. Number two, the other option is I have the essay planning workbook where I have three titles. I show you a plan and then you see three students actual essays for those plans marked with the grade they got explaining why. So, I'll link both of those below. Oh, actually, I've just remembered there's a third one. If you want live help from me, the night before the exam, I am going to be doing a whole hour lesson on the essay. That is my pick a mix essay lesson. I'll link that in the description below. So, yeah, basically I've got everything covered for you for the essay. Right, let's jump in what you're all actually here for, which is the first three out of my six essay titles that I'm going to be planning with you for the 2025 exams. Now, as a reminder, the essay always includes the importance of something and you then have to have your AO1 where you write about the process or the example that you're doing and then your AO2 which is when you're saying why that example or process is important. You need to have four relevant paragraphs to get full marks. AQA recommend you write five to six just in case one that you write is not relevant. So, as we go through these three titles, what I'm going to be sharing with you is the title, five or six relevant paragraphs you could write, and a very brief overview of the AO1 and the AO2, but I'm not going to be doing an entire full plan. So, essay title number one that I'm going to be talking you through is the importance of water in organisms. So, the justification for this title is this has never been assessed on the new spec. It was assessed on the old spec in 2009. Now that could mean that they don't like this as a title for the new spec and it won't come up. Water does come up in osmosis, cohesion, tension, hydrarolysis, photosynthesis, controlling the water potential of the blood. So there is quite a lot of scope here that it does cover a broad range of the spec. And as you saw, there are possible different variants of how they might phrase this, but the key thing is we're thinking about the importance of water. Also, your four relevant paragraphs just to say they can't be from the same spec point. So for every topic I'm suggesting I'm telling you the spec points so you can see that they are different spec points as well. So for the importance of water number one that I would include would be 3.1.7 water. So here's what I go through for my AO1 concepts about water being a major component in cells and in the spec it talks about it as a metabolite in condensation hydrarolysis reactions a solvent for biochemical reactions. It's got a high specific heat capacity so it can buffer temperature changes. We've got that large latent heat of vaporization which provides a cooling effect and strong cohesion which is important in terms of the cohesion tension theory and also for providing surface tension to provide a habitat for some aquatic organisms. So that would be my O1 talking through that linking it to the structure of water. So talking about how it is a polar molecule and therefore you have those two different charged regions and so hydrogen bonds form between a hydrogen and oxygen of two different water molecules. So what would be the importance then linked to this? Well let's take a look at the AO2. You could give an example here. So you could talk through cohesion providing the surface tension and therefore a habitat and that it helps some organisms avoid predators within the water as they can survive on the surface. This could even link to increasing biodiversity because it means you have more habitats, therefore you're going to have more potential of different organisms that can survive there. Or you could talk about the buffering temperature changes linking it to the effect with enzymes. So the concept that it helps to maintain enzyme activity even if the environmental temperature is changing. Number two, 3.3.4.2 mass transport in plants. Specifically, I would write about transpiration and the cohesion tension theory. So let's look at the AO1. You could talk about how water moves through the xyllem due to the cohesion tension theory and that cohesion between the water molecules and the adhesion to the walls. I'd link this to the structure of water. So you could if you didn't talk about it in the first paragraph link that here where you've got the fact it's polar molecule and it forms hydrogen bonds between the molecules. So basically your AO1 is going to be describing the process of the cohesion tension theory. your AO2. So that importance of water in the cohesion tension theory would be this the fact that water is a solvent. So it can carry those dissolved ions such as nitrates that might have been absorbed from the root hair cells into those cells and up the xyllem. Making sure that every cell is getting a source of nitrates that can then be combined with the organic substances made in photosynthesis to make proteins such as the enzyme raisco which is essential in photosynthesis. Number three on the list is 3.5.1 photosynthesis and my A1 for this I'd be focusing on the light dependent reaction in particular photosis. So let's have a look. So I'd go through the process of photosis and that this is when water is split using light energy and you are going to split the water into protons, electrons and oxygen. I would then focus on the fact that those electrons replace the electrons lost in the chlorophyll from the electron transfer chain and that the protons are used to reduce the NADP. by AO2. The importance of photis here is it's meant that in the light dependent reactions we could create ATP and reduced NADP and those two molecules are important in the light independent reactions because the ATP can be hydrayed to release energy to provide the energy for the regeneration of RUBP but also for the energy needed for the reduction of GP into trios phosphate and then the reduced NADP is providing a hydrogen for that reduction of GP into trios phosphate. This is then useful because some of the carbon from the triosphosphate is used to make the organic substances in a plant. For example, glucose, which is an essential respiratory substrate for the plant to produce ATP for all of its metabolic processes. Number three on the list is 3.3.3 digestion and absorption. Let's have a look at what the A1 could be for this topic. So, I'd focus on hydrarolysis. I would give the definition of hydrarolysis that this is a reaction that breaks bonds using water to split apart molecules. For example, starch that you might eat in your food from bread or pasta, potatoes that gets hydrayed into moltos and then moltos gets hydrayed into glucose. So I would discuss that process of digestion of carbohydrates, but you could talk about digestion of proteins or lipids. And make sure when you are describing any of those three, and I wouldn't do all three cuz that' be too much. Just pick one of those to describe. Make sure your emphasis isn't on the enzymes. This title is the importance of water. So yes, mention the enzymes, but the big focus here is each step of digestion is a hydraysis reaction. Breaking a bond, name the bonds. And splitting apart into smaller molecules, name the molecules. That then takes us to the AO2. Now, I'm going to stick with the glucose example that I said cuz I went from starch to moltos to glucose. That starch has now been broken down into a molecule small enough to be absorbed which is glucose. Glucose is small enough to be absorbed by coransport into epithelial cells and the bloodstream and then it can be used in respiration in glycolysis to produce ATP for metabolism or it can be stored as glycogen. So without that water the hydraysis in digestion would not be possible. starch couldn't be broken down, hydrayzeed, and therefore it'd be excreted, and you wouldn't be able to get the valuable molecules that you need from your food into your bloodstream to be assimilated in the body. Topic five we could write about is 3.3.4.1 mass transport in animals. And here I'd be focusing on tissue fluid. So my A1 for this would be the fact that you get that high hydrostatic pressure which is what causes the water and small molecules to be forced out of the bloodstream to form tissue fluid is created by the pressure of that volume of water in the blood. So the importance of the water here is because you've got that water in the blood you get your volume of water going from a larger diameter to a narrower diameter creating this high hydrostatic pressure. That's how you can force out all of these small molecules. your importance of you could then link to this is really useful because it means you're able to bathe your tissues your cells with the useful molecules that are forced out such as glucose oxygen as well as water itself as well as that I would then link to the fact that the water from tissue fluid gets reabsorbed back into the capillaries due to the water potential gradients and that is because the plasma proteins the large ones aren't forced out and this is important because it means any waste produced by your tissues such as carbon diox oxide and ura are transported with that water back into the blood and can be transported around the body and removed. For example, the carbon dioxide exhaled at the alvoli and ura excreted in the nephron in the kidneys. And then my last one 3.6.4.1 we're linking it to homeostasis and negative feedback. So my A1 for this topic would be talking about the property of water having that large latent heat of vaporization. So I'd be explaining here how it provides that cooling effect. My AOT for this then would be saying why it's so important that humans are able to cool themselves down. And remember, you don't actually need to know the whole process of thermmorreulation because that's GCSE, not A level. So it won't even count as a A level or above beyond the spec topics. There's no point talking about it. Just talk about the large latent heat of vaporization and how water provides a cooling effect and then your importance of I would link it to enzymes. So first of all, it helps us to maintain the optimum or core body temperature which is needed to maximize the number of enzyme substrate complexes in enzyme controlled reactions. The fact that we can cool ourselves down means that our body temperature shouldn't increase to the point where enzymes start to denature. So I'd explain that idea of denaturing, how that would impact the induced fit model and therefore lower the rates of reactions. And you could always give an example. for example, that might mean that ATPAS can't work anymore and that would affect muscle contraction as well as the production of ATP. Or you could even talk about enzymes involved in DNA replication. Whichever example you give, make sure you're given an Alevel example. So that's it. That is our essay number one, the importance of water in organisms. Number two, my next essay title is the importance of proteins in the control of processes and responses in organisms. So let's see the justification and possible variance of that title. So this was last seen in 2015. It's relevant to paper 2 topics like enzymes, receptors, transcriptional factors, hormones, and the immune response. And there could be potential variations of this title. So the importance of proteins in regulating biological functions or just in communication and control or in homeostasis and coordination. So let's jump into the possible topics starting with 3.1.4 proteins and enzymes. Let's take a look at the AO1 and AO2. For the A1, I'd talk about the structure of protein. So, thinking about amino acids, peptide bonds, and how you get your primary, secondary, tertiary, quarterary structure. Describing those structures, linking to the bonds and the shapes. Then I'd go on to enzymes and how those have a tertiary structure which determines the shape of the active site. Link this to the induced fit model and enzyme substrate complexes. Then the AO2 the importance of so here we're looking at how proteins are controlling reactions. Remember this isn't the importance of proteins it's the importance of proteins controlling processes and responses. So the importance of enzymes here is how they can control reactions specifically the rate of reactions. So I'd talk about how they lower the activation energy to allow metabolic pathways to occur in at body temperature. And I'd probably give an example. So ATP synthes in respiration or we could be talking about proteins in plants here. So it could be in photosynthesis or DNA polymerase in replication just an example from Alevel number two 3.2.2 and this is looking at mitosis and we're going to be focusing on the spindle fibers which are proteins and how they are controlling the process of mitosis specifically the movement of the chromatids. So my AO1 I would be talking about the spindle fibers, how they attach to the centromeirs, and talk through all of the stages of mitosis, but make sure I'm focusing on when the spindle fibers are forming, what they're attaching to, what they're splitting and moving apart, and how this results in the chromatids being separated during mitosis. Then my AO2 the importance of these spindle fibers controlling that equal distribution and movement and separation of the chromatids to the opposite poles would be this protein control is vital for genetic stability. So for example errors here could lead to cancer or genetic disorders. In particular you could focus on nondisjunction. Although you learn about this in meiosis it can happen in mitosis as well. Or you could write this whole paragraph about meiosis instead of mitosis. But the key importance of would be that you get the equal separation of the chromatids and you could talk about nondisjunction and how that could impact an individual if that did occur. The third paragraph 3.4.1 and actually also links to 3.8.1 as well. So transcriptional factors and gene expression. So my AO1 would be looking at proteins in controlling transcription. And this is where there's the link to 3.4.1 which is protein synthesis. But the main focus is the gene expression, the transcriptional factors that control transcription. So I describe that process of how transcriptional factors control whether transcription occurs or not in my A1. Then I talk about the importance of controlling transcription in my AO2. So for example, cell differentiation and making specialized cells is possible because of transcriptional factors because exposure to these transcriptional factors is what causes some genes to be transcribed and others not. And that's how we get specialized cells. Or you could link it to the development of diseases such as cancer because if you have a tumor suppressor gene not being initiated to be transcribed, that could lead to cancer. So that would be what you need to explain in your AO2. My fourth option is 3.6.4. 4.2 and this is looking at the control of blood glucose in homeostasis. So the A1 could be insulin and glucagon are two hormones which are both proteins and they are controlling the process of blood glucose control. I would talk through either one or the other, not necessarily both cuz it then be too much focus on one paragraph. So then talk through how either insulin lowers the blood glucose concentration or how glucagon increases it. My AO2 then is the importance of so this is important because it's maintaining blood glucose control and it depends which one you focus on. If we're thinking about insulin the importance is that it lowers it so that you don't have too negative a water potential which would cause water to leave the cells move into the blood by osmosis and it would increase blood pressure and also they wouldn't be able to create glycogen stores without insulin. Or if you went for glucagon, then you could link it to the fact that you always need to have that supply of glucose because it's a respiratory substrate. And you could link this to diabetes as well. Paragraph 5 3.6.4.3. And we're looking at the control of the water potential of the blood. So my AO1, I'd be talking about ADH, which is a protein hormone. I'd talk about how it binds to the receptors on the cell surface membrane of the collecting duct and the distal convoluted tubule. I'd also talk about the production in the hypothalamus and the release from the posterior pituitary into the blood and then talk about how this triggers the insertion of aquaporins via a second messenger model. Now that little bit there is actually beyond the spec. But the key thing is you'd need to know that ADH makes the walls of the collecting duct and the distal convoluted tubule more permeable to water. So more water is reabsorbed back into the blood by osmosis and that then means you're losing less water in your urine. So it's a type of osmo regulation homeostasis. The importance of then this is controlling water reabsorption to maintain that constant level or water potential of the blood because if it was too negative you are going to be dehydrated and that can cause dehydration creation of cells and if you have too much water in the blood then that can result in water moving into the cells by osmosis causing them to split or lis and lastly 3.2.4 Before I would link to immunity, the role of proteins in terms of antibodies and antigens and how that is controlling your ability to fight pathogens or infection. So my A1 I'll be talking about how antibodies are protein and I've described their quarterary structure and also their production through the humoral response and ultimately by the plasma cells and the fact that each one has a specific variable region so it can bind to a particular antigen. My importance of or the AO2 is that these antibodies are controlling your immunity. So it can allow things like aglutination, neutralization of toxins from pathogens and also it enables your long-term immunity. And then the final essay that we're talking through in this video before we have part two in another video is the importance of DNA as an information carrying molecule and in gene technologies. And here's the justification. This was last seen in 2019 and it allows links between paper one, so the structure and replication of DNA, also paper two, gene expression and biotechnology. And here are three possible variations of the title because what I just said there is literally the title from 2019 and I doubt they'd replicate the exact same title. Now, 2019 might seem too soon for this to come up again, but DNA hasn't really been a big focus of titles for a while, and 2019 is still six years ago, and some essay titles have looped round after 6 years. So, paragraph one that I'd write about 3.1.5, the structure of DNA and RNA is a spec point, but we're just going to focus on the structure of DNA. Here's the A1. DNA is a double helix with antiparallel strands and complimentary base pairing. It carries genetic information in base sequences. is I'd be talking about the hydrogen bond and giving stability but also easily break those bonds for unzipping during DNA replication to get your template strands. So basically a summary of your Alevel knowledge of DNA structure. Then I get to my AO2. So the importance of DNA is it's a stable molecule. It can be replicated and this allows inheritance. So you could link it to the passing on of favorable alles in natural selection and evolution or you could link it to the fact that the genetic code is universal. also enables gene transfer across species in your gene technologies. Paragraph 2 3.1.5.2 DNA replication. Here's the AO1. I've described semicconservative replication focusing on the role of DNA helilicase DNA pymerase and that the DNA has that complimentary base pairing to ensure copying accuracy. The AO2 then this is important because it enables cell division and continuity between generations and that is going to be the foundations of genetic technology techniques like PCR which mimics DNA replication but it happens in vitro or in cloning expansion in the humoral response if you want to give a naturally occurring example of when DNA replication is important. Next 3.4.2 protein synthesis. So for my AO1, I would talk about transcription. So I'd go through the process of transcription and how it creates mRNA from DNA. Very briefly, I would then just state that translation uses that mRNA to assemble the amino acids into those sequences to create the polyeptide chain. But that's not the key focus. The key focus has to be on the DNA which is in transcription. Then the AO2, the DNA controls structure and function of cells through this protein production. So for example, you can give an important protein from the spec which might be hemoglobin or a particular enzyme. For example, you could also link this to gene mutations here. If that DNA base sequence changes, how that can change the mRNA sequence and ultimately the final shape of the protein produced and you get a non-functioning protein. And that reiterates the importance of the DNA here because when that DNA base sequence changes, you might get a non-functioning protein. Paragraph 4 3.8.1 gene expression. So my AO1 I'd be talking about how gene expression can be controlled by epigenetic changes. So I'd go through the concept of methylation and acetylation. Then my importance of the AO2. I'd talk about how DNA's expression can change in response to the environment and that could be different chemicals or stresses and how this can then affect whether a gene is going to be transcribed or not and therefore affects cell differentiation and potentially results in cancer as well. And you could also talk about how epigenetic markers can be manipulated in therapies or as I said link it to cancer development. Paragraph 53.8.2 and this is recombinant DNA and gene technologies to address the other part of this title the importance of DNA in gene technologies. So my AO1 here I talk about techniques for example the use of restriction enzymes or lies vectors marker genes and how you can actually create clones and copies of DNA fragments. And the copies I probably link to maybe PCR as a process. The importance of this this means that we can use DNA to create genetically modified organisms. So you could link it to maybe insulin production or gene therapy or how it allows diagnosis of genetic disorders or personalized medicines. You don't have to give all of those examples. I'm just saying possible examples that you could pick from for that AO2. And then lastly 3.4.1 DNA genes and chromosomes. So my A1 I've been talking about how genes are sequences of amino acids in the polyeptide chains and also functional RNA. So that could be one key focus of the importance of the DNA. Also that chromosomes carry DNA and ukarotic cells and how their structure allows them to be packaged and regulated. My AO2 here the importance of I could link it potentially to inheritance. So if you have mutations in these genes, how that can affect the offspring, which you could talk about from a positive point of view in terms of natural selection, evolution, or maybe you could focus on speciation. You've got a different concept as well. So that is it. The first three titles that I suggest you have a go at planning and writing for the 2025 exams. So give it a go. And remember, if you do want even more help with your essays, I have got my essay workbook, essay boot camp online course, and I'm doing a 1-hour live lesson, my essay pick a mix session the night before the exam. All of which are linked below. That's it for today, and I'll see you in part two of this essay video. [Music]