AQA A-Level Biology 2024 Paper 1 Unofficial Markscheme:
__ means question is 100% correct!
+Question | Answer | Debate | Marks (91 total) |
Diagram showed 1 fatty acid and Glycerol laggy | Ester Bond Condensation reaction drawn correctly Circle drawn around the OH of fatty acid and H of glycerol | Did u draw one circle or two Two! Would one big one joining both reactants work The question stated A CIRCLE so.. One circle around every ach of the groups involved In the ester bond which i got as one OH group on glycerol and the H on the very end of the fatty acid opposite the COOH group I didn't even realise you had to circle anything kill me now Um guys was swha once JF go L its over for you I drew two circles. One around the H of the glycerol and one round the HO of the fatty acids. Correct?same What if the OH is from the glycerol not fatty acid? How was this 3 marks bruh Was his not 3 marks? Yup. We only need to circle one -H and OH right? THATS WHAT I PUT IS THIS CORRECT??? I think so, that’s what i did too lol Literally revising for chem at the moment and allery chem said that the OH and the H can be any as long as it is on the 2 main OH’S. Im 99% sure its an OH from fatty acid and H from glycerol | 3 |
Which fatty acid is saturated | Stearic acid | 100% | 1 |
Explain the pattern in melting points q | The more double bonds / fewer hydrogen present, the lower the melting point As number of C=C double bonds increases, the melting point decreases | The second thing written is definitely wrong?? It was the double bonds between carbon? More do surely for 1 mark you wouldn’t need to mention packing less closely Y it h u dont need to just saw as ok number of double increas e boili | 1 |
Explain why increase in unsaturated fatty acid results in more phagocytosis | Membrane becomes more fluid as presence of C=C bonds cause the chain to bend so fluidity increases, so it can surround pathogens more easily. So more phagocytosis etc. More engulfing via endocytosis | You have to make some reference to MORE, as thats what the question is asking for Don’t you havne to mention the kinks formed by , because the question specifically talks about unsaturated. Unsaturated bonds kink / bend the tail. Yes you do i remenber on another markscheke u need to say something about kinks or bends I said psedupodia extend more readilly instead of more engulfing is sayuing more enough u reckon
I said more phospholipids so only lipid soluble substances can pass phagocytosis is used to allow other substances to pass I dont think you need to talk about the kinks bacause the previous question taught about the melting point chage - no you do it specifically say unsaturated and tbats c=c causes it to kink and so inc permeability I didn’t mention endocytosis | 3 |
Facilitated diffusion and active transport |
| can you put movement of substances Yes u can I didnt put charged molecules Yeah i didnt put charged either i said substances I remember the mark scheme for a 5 marker on a paper 1 and they just put substances
Can u say molecules? YEA i think an exmaple worked too like saying e.g Na+ | 3 |
What are microvilli? | Microvilli are finger like projections / membrane foldings of the epithelial cells. Their function is to increase the surface area for diffusion. Moose reply Small finger-like projections of the cell-surface membrane (that increases absorption of products of digestion) Technically only increases SA | I said microvili a would folded membrane work?😔 YE PPP i put membrane foldings on Are they not found on villi? And specifically in the SI They aren’t found exclusively in the epithelial cells lining the ile n um so i didn't mention that I put hair like lol Probably fine I said small finger like projections on th yo e cells lining the ileum/cell membrane? Yeah that’ll be fine I wrote small rectangle shaped cells on the cell surface m it embrane of epithelium cells on stomach. Does it work?? I said small fingerlike projections found on villi in the SI Can i just say foldedcell surface membrane? I said this too to increase surface area to volume ratio for diffusion Can we say extensuons ofmembrane? C | 1 |
Number of monosaccharides present: | 2 | Sucrose, fructose and glucose were in the molasses, and sucrose is not a monosaccharide I didnt read the question properly and answered with Fructose and Glucose, would i still get the mark even if i have just mentioned 2 monosaccharides did you put 2? Like just number 2 ohhh u put fruc and gluc - mmh u did get that its both mono so maybe but seeing as it said no. specifically im not sure - they might give u benefit of doubt potentially. Dw its only 1 mark What about galactose? What about it? Isnt that a monosacharide t? If u feel dumb dw i misread the q and wrote 4 lol i knew it was 2 but i still wrote 4?? I was lagging in that exam | 1 |
How to test for reducing sugars and what is the expected result for molasses | Add benedicts and heat in a water bath at ~90 C you dont need to mention the temp tho Boiling is for non-reducing sugars test (boil with HCl, neutralise with NaOH) - NOT RELEVANT HERE
| Can you just say also red precipitate will be observed????????????????????????????????????????????????????????????????????????????/ YEAAA May need to write BOIL(has been a requirement in past MS I got cooked then aha I thought you only had to add BOIL for non reducing when adding acid and BOILING?? You have to say its heated and i thi is nk its dangerous to put over a bunsen up flame thats why water bath Boiling is for non-reducing with HCl, surely alos precipitate would be maybe yellow or orange cos su crose is non-reducing no it aint u donut - yes it is pal read the textbook sucrose is non reducing I just said about brick red precipitate for the observation bc i forgot starting colour - yea thats fine 90c??? I swear they allow 60c? Dont think temp is required! - its not, people just wanna be extra for no reason Sucrose is non-reducing? So no colour change? Glucose and fructose also present which are reducing I see Is it a must to write heat in water bath?? I forgot to write that, sob. Explanation of result would be hydrolyse the glycosidic bond through molecule of h20 wouldn’t make sense to not do that cause it was 3 marks! They are monosaccharides so no glycosidic bond. You realise there was sucrose which is a disaccharide so you hydrolyse the bond Well the answer How you gonna hydrolyse sucrose? It’s NON REDUCING. Are you like okay? If in the context of adding acid and alkali obviously I’m referencing sucrose. Do you not know the test for non reducing? Your forming glucose as a by product which in turn higher concentration would form red ppt! You the question was talking about reducing sugar so u say beneditcs+ heat in a water bath+ brick red ppt observed - I think they would honestly credit any coloured precipitate due to presence of sucrose well the question specifically say reducing but i understand where u are coming from so i presume there will be a range of colours in the appropriate range but u defo had to say benedicts + heat in water bath. Yeah I agree on the test but it asked for results with Mollases not just your standard benedicts test but swear down the q said just reducing either way theres probs a range of colour and red ppt and whatever colour u put might fall but most people put red and its only 1 mark. Yeah really not that deep tbh but I reckon theyll accept any but you had to explain the result either way yeah well 3 marks - one for benedicts cus u identified its that, one for heat in a warm water bath cus some ppl will leave that out or say smth that done wor and one for colour change It only said smth on what u observed | 3 |
| Its 1.62 It’s 1 - its not one u hippo (1.62) Although this was over, AQA often specify that answers should be rounded to the nearest whole number. Well if u increase 1.62 it dosent align with what they said as no less ( it was no more xxxx ) than 5% when u camore lc than 1.62 it dosent work. So its 1.62 no So you can’t have half a teaspoon How many marks was this question? One mark LOOL Thats the crazy thing, the question isnt worth it but its really annoying, if you dont get the correct answer, just because you rounded or not rounded your answer. My OCD triggered af. he |
I’m so upset I got 1.62 and then rounded to 1.6 which was stupid cause that won’t go over the threshold (feeling very stupid rn) dont worry some people put 33 LOL but i think 1.6 will still be allowed, there could be a range and even if not its just 1 mark you are still going to get a mark for your methid, - logically it dosent make sense though, it would be difficult to get 1.62 of a table spoon | 2 |
Vitamin A is a fat soluble vitamin which is transported to the ileum via micelles. Describe how vitamin A is absorbed into cells surrounding the ileum | Absorbed into micelles with monoglycerides, fatty acids, and bile salts, make them more soluble in water so can enter cells by simple diffusion, can then be reformed or put into vesicles by golgi (monoglycerides probably not needed was a similar question in paper 1 2020 and you just needed fatty acids) | Where do u guys think the marking points were? Absorbed into micelles? Don’t the micelles surround the fat droplets instead?? accidentally put insoluble not soluble but everything else the same am I alright? Bile salts emulsify the large lipids into small fat droplets.. Does it really dissolve the fats?? I dont know where you guys are getting monoglycerides and fatty acids from. It said it was lipid soluble it never said it was a lipid. I literally googled the structure of VITAMIN A and most of them are not lipids. I said micelles transport fatty acids and monoglycerids to the lining of the ileum. I also talked about lipase at the end since i was unsure of the marking points I did my nt mention monoglycerides :( i just said bile salts associate with vitamin A to form micelles Don't think you had toy about vitamin A Maintaining conc gradient of vitamin A to cell lining ileum? It says describe how its absorbed right? Yeah but i think you had to mention the micelle bit bc thats how they get in Where are the monoglycerides from? I thought it was application of lipid digestion so i just wrote that process and added vitamin a in Oki I talked about lipid digestion as well. Monoglycerides are formed due to lipase hydrolysing the triglycerides Is chylomicrons a final marking point? Bro theres no mention of lipids being absorbed, its about vitamins, the question doesn’t say if vitamin is a lipid or not. Fat-soluble vitamins (A, D, E, and K) are absorbed along with dietary lipids in micelles via simple diffusion. This is why you are advised to eat some fatty foods when you take fat-soluble vitamin supplements ^^^ thats what it says online or people referenced lipids because it said micelles paper 1 on the 10th of ju i hate ppl like u like EVERYONE has chem on | 3 |
What is the tube shown in Figure A? |
| was it not bronchi cos there was 2 I put capillary :( same bro tubes . bronchioles can branch.. No it was only one lung ik and each lung has one bronchi not two. Bronchi branch into bronchiles and then alveoli. Shouldnt it be bronchioles? Yes it is deffo bronchiole Bro i fully missed this question i didnt even see it what | 1 |
Calculate the actual size of the diameter | Its 75 micrometers ! | (A really long winded convo between 2 people was here - no need to elaborate and the messages have been deleted) | 2 |
Explain how you
| Diaphragm and External intercostal muscles con tract, pulling the ribcage up and out This increases the volume of the thoracic cavity, decreasing the pressure inside the alveoli, so air from the atmosphere moves into the lungs down the pressure gradient | lovely question this was I put the diaphragm contracts but not hat it flattens, is that ok. (as long as you say volume of thoric cavity increases) Did u have to mention gradient ive not seen it in past papers Do you have to say volume of thoracic cavity increases. I only said pressure decreases (probably ok) you have to say the volume increases and pressure decreases Think there will be more than 3 marking points? No for thi | 3 |
Why was the sample thin in the opti see cal microscope | Light has a long wavelength so cannot penetrate thick specimens However, light can penetrate thin specimens,allowing the scientist to view a high resolution image of the enpithelium. | You had to mention sin gle layer of cells It would be more accurate, yes, but I'm not sure if you had to? I paraphrased for the purpose of being quick Its a really common question and ms always says single layer of cells I said the same but would single cell thick be a marking point. Surely one cell thick is way too small of a sample to even cut precisely fr Could you also put so any dye used can be absorbed to clearly see the sample ? | 2 |
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Why was the air pressure increased inside the animal bladder filled with molasses and an air pocket, the whole thing surrounded by water? | Because there is a lower water potential in molasses compared to water, so water molecules diffuse into the bladder by osmosis down a water potential gradient through a partially permeable membrane, so volume of molasses and water solution increase,increasing hydrostatic pressure reducing the volume that the air can occupy, thereby increasing pressure | Sick diagram btw YEAH!! LMFAO took me a second with my finger - but thank you :) I would assume you need to use the term water potential - the exam board is extremely specific. If you say everything else but hydrostatic pressure do we think that the mark will still be given if you describe it. | 3 |
What change was made to reduce the air pressure in the second experiment | Old was 800 kPa, New was 160 kPa higher.so 960kpa So make increase WP outside so more water diffuse in by osmosis Dilute molasses with distilled water using 1part molasses to 4 parts distilled water? I’m | YES YES I GOT 20% INCREASE WOOO I said 80% less conc?? Percentages are fine because its basically the same thing yay tks I said just “less concentrated” It asked to use a mathematical equation so thats why i wrote 5x The question I think it says the new pressure INCREASED by 160kPa from the original 800kPa so the ms would be wrong. (I might be trippin fr)(I swear I saw the word increase) the ms is right (its not increased by 960) no it does inc by 160 the mark scheme dosent nec mean its right The pressure did not increase by 5x. Its 960(new) compared to 800(old).pressure increased by 20% This is wrong^ its not ots correct I put lower the water potential of water by adding solutes so less water moves into bladder It specifically said a change to do with the molasses didnt it? PRETTY SURE T SAID THE SECOND EXPERIMENT PRESSURE INCREASED BY 160 AND FIRST BY 800…SO ITS A 80% DECREASE IN PRESSURE BETWEEN THE TWO EXPERIMENTS AND HENCE DECREASING CONC OF MOLASSES BY 80% IS THE CORRECT CHANGE. (it didn't say the second one was 160kpa more…so it's not 960) Ok that explains why I saw the words increase. No it was 100000,0000^ a 160 increase | no 2 |
Structure of mRNA vs tRNA | Linear vs clover shape Mrna has a Codon vs trna has an anticodon No AA binding site vs AA binding site Contains no H-Bonds vs Contains H-bonds | can you put ter/longer?shorter no clue ^ internet says tRNA is shorter (I wrote tRna is short - like you ~I said less nucleotides Could you have tRNA has two codon n s, mRNA has one? Probably Helix vs Clover leaf? Smaller vs larger? Its structure so idk if you can say size i have a table im sure that counts its still structure? -I said a similar thing But i talked about how tRNA only has 3 bases and mRNA has more? Trna has hydrogen bonds right ? i talked ab exons in mrna ? There are no exons in mRNA, only pre-mRNA Can u say there are introns in mrna but not trna I put mrna is less stable | 3 |
Uncertainty in the 4mm rul ouuuu er | ∓ 0.1mm 25% uncertainty Its 0.5 for general, only the second part is asking about when a measurement is taken Is it not 1 mm because 2 judgements? The total error is 1 but individual is 0.5 and thats what they wanted for the first bit But it said what would the uncertainty for the measurement be… it wanted uncertainty of the ruler THEN it wanted percentage uncertainty | Isn't Percentage error unc/measured value so 0.5/4 The total error is 1 mm because you have to apply the error twice and 1mm/4mm is 25% Is it not 12.5%, as 0.5/4 x 100 = 12.5%?? No error is counted twice so its ¼ * 100 WHY IS THE ERROR COUNTED TWICE? Because you are technically doing two measurements, you have the error of the 0 mm line, and the error of the 4mm line, so 2 errors That the uncertainty? How do you work our the 0.5mm, can anyone explain, I just did 4-3 lol | 2 |
P<0.05 What conclusions can be madq was e about the experiment? | R value was -0.98 so strong negative correlation p value less than it 5% so probability results are due to chance is less than an 5 | Would you not also say that results are significant Do You have to say strong negative can u just say negative Strong negative is more right but negative might be fine? ty And can u say “there is sufficent evidence to reject the null” instead up of the p value thing Could u say there is a statistical significance? Cannot say results are significant isnt it difference? Strong negative linear correlation? Since r value is only measure of linear relationship tbf i dont think it’ll impact the mark | 2 |
Describe appearance and behaviour of chromosomes during prophase and anaphase | Prophase - Chromosomes shortern, thicken and CONDENSES so becomes visible - Chromosomes appear as two sister chromatids joined at a centromere Anaphase - Centromere divides - Sister chromatids are pulled to opposite poles - V shaped | I fucked this one mannn ] Same :( Shit i didn’t mention the 2nd bullet point of prophase RIPPPPP I'm actually so stupid because I read it as prophase and metaphase and so talked about metaphase and notanaphase | 4 |
| Mitotic index = number of cells undergoing mitosis or with visible chromosomes /total number of cells Increased distance caused a decrease in mitotic index, less cells undergoing mitosis Or vice versa Increased distance caused an increase in the number of cells in interphase or cytokinesis Unable to comment on number in cytokinesis and interphase respectively | No. it was how the distance affects the proportion of cells in the same stage of the cell cycle For word equation i wrote no of cells with visible chromosomes/total number of cells - would that be good? -undergoing cell division (or something describing the look of cells during) i also included how 2.0 mm. Was the maximum distance of mitosis and how beyond this value no more mitosis occurred The question said use figure 4 so i think you had to make some reference to the graph | 1 3 |
c) what does figure 4 tell you about the amount of cells in each phase of the cell cycle | I said increased proportion of cells in interphase further away from the root tip . At 2.4mm there were no cells undergoing mitosis or all cells were in interphase stage I said the same wooo | Did any of u mention meristem cells mostly at root tip | ^ |
Two things which make aorta cell wall adapted to perform its function | Thick Muscle walls Withstand high blood pressure within lumen of aorta (keep blood at high pressure) Stretch during ventricular systole Recoil during ventricular diastole Smooth pressure surges and maintain blood pressure (Allow artery to rebound after heart pumps)
See | Can i say small lumen so high blood pressure to pump blood to whole body??? (was talking about the walls on okly?) I WROTE LUMEN AND REALISED WITH LIKE 2 SECS TO GO and then i wrote elastic walls so recoil? Walls only i'm afraid Can you say smooth endothelium so less friction/less fr ^ yes THIN SO SHORT DIFFUSION PATHWAY? Very wrong why? Can you say thikcn muscular wall contracts and relaxes changing lumen size to control blood flow? Supplied by blood vessels? ^ no that Guys can u talk about valves preventing backflow of blood? NO the aorta is an artery so does not have valves Ok thank u 🙂 - Semilunar valves would be accepted but the question asked specifically about the wall What about the aortic valve tho or did i make that up Yup u did. There no valves in arteries, only in veins Can you say thick walls instead of thick muscles????? Yeah i said that and that they withstand pressure
can you talk about vasodilation and constriction?? | 2 I thought this was 2 marks (i agree) Was this not 4 marks? No only 2 It was 4 marks. |
Over 60s thing with the tear in aorta and diameter and aneurysm: Conclude the r | I said average risk increases as diameter increases.
You can also mention th at the chance of developing an aorta with a diameter >4.5 is really low because a low proportion of the population had an aorta diameter >4.5. It was CONCLUDE not EVALUATE It didn’t ask about other ages - it asked about what the data told us. So whats the answer? It said an aneurysm causes aorta diameter to increase. So having an aneurysm increases the chance of having another? | Could you also talk about how only people older than 60 were Sa? Smaller sample for over 60 so not representative? It didnt say evaluate, it said what conclusions can be made. It was only three marks.This was not an evaluate question so answers about stats test is incorrect. Plus the number of people was small because the chance of developing an aorta with a high diameter is really low, so you can’t say low sample size. Yes i agree with you - shall we change answer? Thank god, i was reading everyone writing evaluate answers and it wasnt the command word… Yes. Yes You had to talk about aneurysm risk Good - wasn’t really sure what to write though… thought there wasn’t very much to comment on. | 3 |
Results table for apple PPO | Just a results table I wrote the time in mins 1 dp.. Is it alright?? Should be s so convert to s, so do i lose marks if not in secs?? They didn’t mention a specific unit as far as i can remember ^ probably depends on what units you used, bc if you put ‘min’ i dont think thats official units you have to write ‘minutes’ tysm, hmm i did that.. So no marks lost eh? Depends im not 100% sure but they didnt specify what units so i dont see why not | no Okayy thanks I wrote in seconds but minutes would have been fine too (as long as you wrote e.g. 10.5 for 10 m 30s) waiut no i didnt do that i put it in decimals so 10.5 yeah that’s fine as long as you didn’t write e.g. 10.3 for 10min 30s Did not do that You’ll be fine 👍 Did you write x.0 for second mean? Bc 1dp? Will i not get any marks if I wrote it as 10m 3secs? 😭 ^ heading of units should be in the table with a solidus (/) Would have been better to have
I put repeats on the left and variety on the top ~ me too i only put 1 2 and 3 did i need to put repeat? | 3 |
Why was D slower at going brown than E | Less PPO concentration in D compared to E, so less E-S complexes can be formed therefore the reaction is slower so it takes longer for a colour change to be observed | I put higher. SILLY sconcentration of PPO in so more oxidation etc. higher PPO conc same Yep same There is probably 2 answers for this one for higher conc of substrate one for enzyme? Yeah i agree - although presumably enzyme conc had to be equal for first experiment to be good? The apples were 2 varieties, so the PPO conc cant be the same right? No because they werent testing that they were testing the colour change? Ahhh Oh You can say different enzyme concentrations because they are different varietes so it is something inherent | 2 |
How to prepare the apple so that both are faster (NO REFERENCE TO MASS OR VOLUME) | Any reference to preparation of apples e.g. cutting apple differently, thinner slices, grooves in slices, reduced thickness, cutting larger cubes into smaller cubes, drying apple to remove moisture ^Surely this is wrong because if I have an apple that is a cube of 1mm and cut it into 4 smaller cubes of 0.5mm^3 the volume of the cubes has changed with it now being 0.125mm^3 per cube You cannot say temperature as the question asked how to prepare the apple, not the experiment itself. ^Who r u to bold underline this jokeman get undone It said NO REFERENCE to mass or volume, not NO CHANGE to mass or volume More SA for the oxygen to come into contact with Qnonymouse wombat i have a question | Had to say to cut the apple differently to increase the speed (i said cut into a sphere as that has higher surface area) Had to say reduce the thickness of the apple slices to decor diff distance so oxygen reaches quicker and reaction occurs quicker I said hang the slices in air so all of it is exposed to air (cuz in question it says they were on a plate so obv not all of it is exposed) I said dry the apple so more oxygen can react with phenol? Probably ok So as long as no reference is made, answer should be fine What about drying the apple? Moisture increases diffusion distance maybe? Or wishful thinking… yes this is fine Thank you! Doesn’t drying the apple change its mass tho?? The question said not to change the mass.. I swear it would be temperature as the experiment was timing the time for the apple to turn brown, increasing surface area wouldnt decrease time take for brown colour to appear as the oxidation is occurring on the surface of the apple in the first place. 100% i wrote temp as well. Oh did it say u had to prepare apple differently? I said place the apples under pure oxygen so more concentration of oxygen so more E=S form frequently. Can’t increasing temp get a mark then? i don’t recall it saying how I wrote increase temp because the cutting differently how does that do anything i swear WAS TEMP NOT PART OF THE PREPARATION??? Bro cutting it differently increases SA no it is But surely going higher could denature enzyme? 30 is already quite high ITS TEMP cutting into smaller cubes is a correct answer because this doesnt affect volume or mass- the same apple sample is still there but just in smaller cubes - this increases the surface area for a faster reaction so brown pigment formed faster I said use a higher temp so more Ke so more ESC form? Same yea same I said cut grooves into walls of apple cubes so more sa exposed to oxygen for reaction? Is this good? (as long as the volume doesnt change then yes) dont the volume change when we cut up the apple cube to smaller pieces?? No because you cut it up into multiple small pieces It said NO REFERENCE to mass or volume, not NO CHANGE to mass or volume. Wouldnt cutting it up change the mass as well No because if you cut a 1g apple into 2 0.5g chunks, neither the volume nor the mass has changed But it didnt say not to change it, it said not to talk abotut it. Yes so saying cut it into more pieces is fine as you are neither changing the mass nor the volume Whos this guy who thinks he gets to be in bold im unbolding it Increase temperature? Thats what i wrote also Omg cus it said u cant change the mass/volume i thought u cant slice it :( i said add more of teh enzyme bruh im acc so cooked fr Is temperature right tho? I think so because temperature is still a part of preparation for the experiment Would it count to say if you remove the skin of the apple to allow more oxygen to be exposed to the surface area? Yes Reference to es complexes has to be made. More brown product formed only due to more substrate conc or obviously other factors would be plausible! Who the hell is talking about surface area 😭 | 3 |
How should the student measure the amount of PPO successfully? | Compare apple with colour on diagrams - 2nd box should be ticked | Not colorimetry as an apple doesnt let light through Nooooooo what rlly - has to be in a solution for colorimetry Yes in solution only T correct yesir | 1 |
The Student got -30% as the percentage difference from stroke volume of diseased person compared to healthy person, BVB thing what did the student do wrong | 35.3%. It has to be positive. 69.6-45. 24.6 / 69.6 * 100= 35.3 The student incorrectly rounded -35 down to -30. Problem of the student- the student subtracted 45 from 69.6 thats why she got -35.3%.. T hats what i wrote.. Student got -30% mate. ik I got 55% 0_0 I got 55 I got 54.7% I got 55% same^ I got 35 oops Bro wtf Should we ha ve got 30%?i think its to 2sf in biology the question was how much greater the volume of the healthy was in % than the unhealthy right? Oh noo so do i lose a mark?? was it not 55/?? My smart friend said around -35% and he is smart so he must be right |
This question was awful 😭i got 35.5% change but wasn’t sure on the symbol.. Question was worded very weirdly Probably ecf if you got 55 ish I put a negative answer :/ bro i ignored this question Did you have to put it in decimal point- i pur 35% ?? | 3 This stumped me getting different results for both but i put -34.7% |
Amino acids coded for | Phe Arg Ala | 1 | |
Type of mutation | (Base) substitution | WHAT? Is substitution okay? I wrote substitution - think it should be fine Probably i just specified base to be sur/e Okay// I put silent mutation. I wrote this too, it should be correct. Well that’s wrong | 1 |
| No change to enzyme function - genetic code is degenerate; both codons code for the same amino acid | Is this right or not.? People are telling me it changed from Arg to Ala when i swear it didnt. There was no change to the amino acid sequence, no. thats what im saying but everyones agreeing its changed. It was Arg both times right?a yes Yeah, no change in amino acid | 3 |
How many male frogs did the mating call | 20 | Had to calculate 2.5% from the table and multiply by 800 | 1 |
Explain one change to both male frog populations to increase the number of mating calls | Increase the female frog population size | (there were no female frogs to i begin with?) -i was rushing so i put use less EE2( i forgot the hormone name) I said increase proportion of sexually active males? i said conduct the experiment during mating season? - samee More sexually active females???!?!?!? I put more sexually active females too i put add females Same, I put add females Same as me same Why would it would be to do with females bc in the question the population was only male frogs I put increase males, am I cooked? SO TRUE why would you have demales when there was no reference to beging with How would increase population do anything because its the proportion no of mating calls not the number id use less I said increase number of sexually active frogs ffs Maybe reduce area they are given to mate ? What about play female mating sounds but nah surely ther are askin abt the 2 MALE groups????? | 1 |
Use table 6 & 7 to explain the effect of ED22 on frog breeding | Females spent half the time in courtship so more breeding can occur 0.5% difference in mating calls between ED22 and none. But the decreased courtship time is more significant so over a specific time period more breeding is likely to occur with ed22. Assuming frog population is large. | ED22 decreases frog courtship time. As the habitat contains ED22 so female frogs are less likely to feed the males as they males consume ED22 from the habitat Less raping mating??(please correct me) Can you say less places to breed? Cus like loss of habitat cus of the sewage and all that? Surely the less courtship time actually means mating happens at a faster rate so more breeding. I thought cus there was less time for courtship, the ritual would not be completed fully? so less mating Thats how i read it? When ED22 was present the courtship was slower so mating would also be slower as for mating to occur u need courtship behaviour. I thought it was faster 8 seconds compared to 16 seconds. 16 seconds was no ED22 ? I cant remember Im pretty sure im right. But then wat is the reason becuz there is more ED22 in the habitat so less females will feed the males? I dont think the second marking point is a valid reason.Any idea wat the 4 points are? I think i made my answer to complex so probably wrong tbh Thanks for the chat :) i had a similar reasoning to this^ Please state ur reason here: Can u say less time available for pair bond or synhcronised mating so reduce fertilisiation results in less breeding, because it said to explain for the reduced median time for females? No? Its less time 8 compared to 16 Sorry i meant less time therefore less breeding. Is that ok as an answer Reason: | 4 |
Explain how you could use cell fractionation and ultracentrifugation to extract a sample of nuclei from muscle tissue | Homogenisation - homogenise the muscle tissue to break up the organelles and filter to remove debris Place in cold, buffered, isotonic solution Cold - to reduce enzyme activity Isotonic to prevent enzymes bursting Buffered to maintain a constant pH and prevent enzymes denaturing Filter to remove large cell debris Ultracentrifugation - Spin in a centrifuge at a lower/high speed Produces supernatant and dense pellet at the bottom Pellet contains nuclei Pellet at the bottom due to most dense Nuclei at the bottom as they are heavy | Do you have to say “ice” cold? No Sediment over pellet? Does it matter - nah Forgot to write pellet and put high speed instead of low, am I cooked? Then i am cooked too. I wrote high speed.. yes may be cooked u have to say lowest speed for the first pellet Its high speed. Yes it is comparatively lower than the other speeds but the speed is still high. if you explained the high speed as being comparatively lower u shld be fine. Put high speed too. :( Don't forget to EXPLAIN!! | 6 marks |
Explain the role of organelles in production and release of enzymes in an animal cell(NOT transcription) | Golgi Apparatus - modifies proteins, packages proteins into golgi vesicles for transport to cell membrane and release of enzyme Ribosomes - site of translation, forms 1 structure of enzyme (polypeptide chain of amino acids) Translation (as long as with reference to organelles) Endoplasmic Reticulum (rough) - produces and folds proteins Mitochondria - produces ATP for protein synthesis Nucleus- nucleolus produces ribosomes which are the site of protien synthesis accept exocytosis or remaining in cell | Why is lyosome, mitochondria, nucleus here? Surely lysosomes arent involved as there enzymes would be hydrolytic ones and the question never asked for the production of hydrolytic enzymes How r they involved? Cuz they said u cant write abt transcription so no nu8celar Are tRNA and mRNA organelles? could you write about DNA replication ? NO! No, but you can write about translation - yes I wrote about that too bc it only mentioned no transcription TRANLSATION IS NOT A ORGANELLE!! Ribosomes is an organelle used in translation Ribosomes can be mentioned - see to the left. Nucleus, no? They said no transcription I said enzyme woud get put into a vesicle and released by exocyosis. Is that correct, yes by golgi Where are the marks for this? Was it an explain? Points (correct if wrong):
no way i fked this question | 5 marks |
Describe the structure of ATP. Outline how named enzymes break and synthesise ATP | Adenosine triposphate consisting of (adenosine which consists of) adenine and ribose and three (inorganic) phosphate groups ATP is a nucleotide derivative ATP Hydrolase/ATPase - Hydrolyses ATP to ADP and a Inorganic Phosphate (Pi) ATP Synthase - synthesises ADP and Pi to form ATP in a condensation reaction.
Condensation Hydrolysis ATP synthesis: Respiration and Photosynthesis Should we mention the processes atp is used for? No right? I Enzymes so complimentary etc. | I put ATPase instead of hydrolase do u think thats ok? - Yes :D No, ive seen reject ATPase on previous ms WTFFFF WHYYYY. Were we supposed to know that:( i put triose sugar am i cooked 💀? Absolutely yes Its ok i got cooked as well. Academic comeback on p2 AHAH FRFR DO you have to write “Adenosine triposphate” I lost mark on ATPase and for saying adensoine do u think i will get a mark for saying phosphoanhydride bond between phosphates? Guys was i allowed to put pentose sugar??? I don’t know I put pentose I sd it says that in the textbook RIBOSE?? I drew a diagram… very labelled - is this okay? Yes u can draw diagrams Can u said a condensation reaction? Yup i checked the textbook now, u can call it condensation reaction Thanks Surely ATPase is valid. Yup it is What are the 4 points Guess u have to describe the structure of atp, prolly 1 mark. the formation and breaking up of atp will take take the 3 marks ig. Only 2 enzymes tho so 1 mark for structure 2 marks for enzymes last mark? Would anyone know if atp hydrase be accepted or is that not an enzyme | 4 marks |
