Is it normal to feel like they tested everything except the things you nailed??Yep. In 2017 a bunch of us spent heaps of time the night before going through specific immunity and then didn't get any short answer questions on it haha
Pretty easy and straight forward exam...I've heard that from a lot of people. Bit surprising given people did quite a bit better on the 2018 exam than the 2017 exam. Would have expected this one to be at least as difficult as 2018 again.
What did you guys put for the Zika virus question as to why they couldn't correctly identify the antibodies?I wrote something about the constant region of antibodies being similar and the differences in antigen binding site being very minute and small... probably wrong though.
What was the one where they transcribed the structural gene and it said what molecule does it make?
Options were
Repressors
Transcription factors
Lactose
mRNA
What was the answer to the limitation question?
What was the answer to the what affects DNA movement in gel?I don't know the specifics of the question, but the size of the DNA fragments (base pair length) is what typically affects the movement in the gell.
What was the answer to the what affects DNA movement in gel?
I said that the environmental temperature was not controlled, so it could be fixed by doing the experiment in a room with a controlled temperature.Oh damn that's actually smart. I just said they should repeat it more lol
I think we also had to mention charge, and how it moved towards positive electrode (think I lost a mark here, didn’t explicitly state DNA was negatively charged :()but in happens in a lab?
I also said that wind currents could affect movement
but in happens in a lab?
DOUBTING MYSELF BUTI think that question was talking about post transcriptions modification, so like most of the 300 monomers were introns and spliced out
FOR QN 1B
where it ask why 300 monomer only form 10 amino acid thingy magic
i just refereed it different codons can form the same amino acids where these codon a degenerate meaning that the having different nucleotide but form
what was the answer to the brain size mc question?? i was tossing up between homo sapiens and homo floresiensis, but ended up choosing the latter. now i regret my choice lol.I'd be shocked if it were homo sapiens, because florensis was was later than all the other small brain hominoids whilst the difference between Neanderthals and sapiens is like.... small
"I think that question was talking about post transcriptions modification, so like most of the 300 monomers were introns and spliced out"yesssss I wrote that but do I lose a mark for saying not saying it's spliced out
yessirrr makes sense
I'd be shocked if it were homo sapiens, because florensis was was later than all the other small brain hominoids whilst the difference between Neanderthals and sapiens is like.... small
What was answer to whether the Denisovans and Neanderthals were one species ?
I'd be shocked if it were homo sapiens, because florensis was was later than all the other small brain hominoids whilst the difference between Neanderthals and sapiens is like.... smallI too said H. florensis because the key wording was "Which one did not follow the usual trend of hominid evolution?
Oh damn that's actually smart. I just said they should repeat it more lolI'm not exactly sure whether my answer is viable, but I mentioned that they could extend the range of temperatures tested from 5-> 35 to 5-> 90 degrees as the experiment was only limited to 35*C (note that at higher temperatures the enzyme denatures at the active site thus not able to conduct the reaction)
I wrote something about the constant region of antibodies being similar and the differences in antigen binding site being very minute and small... probably wrong though.I said something similar too + I mentioned that the structure of the antibody has 2 light chains and 2 heavy chains + 2 antigen binding sites.
Funnily enough, found it much harder than 2017 and 2018. I made some silly mistakes...
Hey Pheonixxfire, could you upload photos of the exam?It's still under VCAA copyright so we can't post it here until after they put it up on their own website.
It's still under VCAA copyright so we can't post it here until after they put it up on their own website.
Ok sure, what was the question that had no right answer tho? And why is 20 NA?The question about photosynthetic rate at varying light intensities. Question 20 is on the page of the exam that I'm missing.
The question about photosynthetic rate at varying light intensities. Question 20 is on the page of the exam that I'm missing.
I think you might be reading the graph incorrectly. The line plateaus at a photosynthetic rate of 40 (on the y-axis); thus before the rate of 40 is reached, light intensity is the limiting factor. ;DYikes I should really know how to read a graph by now. Yep you're right.
Also what about why does mutation in bmp4 affect phenotypes? 3 marks
Yep,couldn't conduct comparative anatomy of a finger and adult tooth ,insufficient information hence without dna analysis the difference between the two species cannot be determined
I wrote something about the fact that due to BMP4 being expressed less, CaM had more effect on the size and shape of the beaks. Idk im probably wrong thoo 😂
Anyone know what the a+ cut of will be? Or a prediction even
probably higher than last year.. maybe in the high eighties? but theres really no way to knowIt won't go up that much.
I didn't know how to justify why scientists used Nuclear DNA instead of mitochondrial DNA. I bsed it and said that "Mitochondrial DNA is passed down maternally and is highly conserved whereas nuclear DNA contains DNA from both parents which allows scientists to notice evolutionary links in similarities of DNA between Denisovans and Neanderthalensis." (Yeah def not right)
I wrote something about the fact that due to BMP4 being expressed less, CaM had more effect on the size and shape of the beaks. Idk im probably wrong thoo 😂
I wrote along the lines of...
The mutation of the gene BMP4 results in the changes in the intensity, duration and the times of the gene being expressed during embryonic development. And variation in these factors result in morphological changes, if there is a lot of variation it results in different phenotypic variation.
Phoenix is this right?
the question was question was quite stupid in my opinion.
I answer yes, because of the different locations where the fossils would be found, I think I was wrong though.same i said yes because they were found in europe and eurasia & png lol
Anyone know what the a+ cut of will be? Or a prediction even
I thought it was the opposite? I wrote that mDNA had no repair mechanisms when mutations occurred and therefore had a fast mutation rate, which made it difficult to measure degree of similarity between two species that had split off a long time ago. By that point in the exam I was basically pulling stuff out of my rear end though so this is probably completely wrong.
wrote homo sapiens,cant remember what page in the atar notes book states it ,but out of all hominid, homo sapiens do have the largest sized brain
it was trick qn tbh
how do i know what the questions are for multiple choice?
I wrote something similar. It seems right to me
Ye it was a bit tricky, but the correct answer was Homo Flurosence [/i] or however you spell that. Because it was the only one out of order compared to all other homo species.
I bs'ed on how nuclear DNA has more genes than mitochondrial DNA, thus would be more suitable to compare as there would be more differences or similarities to sequence...??? :-[ ??? ???Me too! I'm crazy insecure about that answer though lol...
I don't know how that could be the answer. The question was referring to brain volume in hominins. H. Sapien doesn't follow the trend because it's brain is smaller than Neanderthals.homo floresiensis is known to be one of the exceptions to the rules because it's got significantly decreased features (smaller skull, small in general). It doesn't follow the typical pattern.
I bs'ed on how nuclear DNA has more genes than mitochondrial DNA, thus would be more suitable to compare as there would be more differences or similarities to sequence...??? :-[ ??? ???
homo floresiensis is known to be one of the exceptions to the rules because it's got significantly decreased features (smaller skull, small in general). It doesn't follow the typical pattern.
Homo sapiens may differ slightly but not as much as floresiensis.
HeyOh no for me question 11 was the worst by far. It was like 8 marks on different sources of errors and I bs'ed the whole thing
What was question 11? Experimental design?
I'm missing that question and the end of question 10 i think. I can try and get a copy of it if you'd like solutions for it but I haven't seen any discussion on it so I dunno if that means y'all just found it really easy?
We're just about done with the rest of the solutions btw.
Hey
What was question 11? Experimental design?
I'm missing that question and the end of question 10 i think. I can try and get a copy of it if you'd like solutions for it but I haven't seen any discussion on it so I dunno if that means y'all just found it really easy?
We're just about done with the rest of the solutions btw.
Oh no for me question 11 was the worst by far. It was like 8 marks on different sources of errors and I bs'ed the whole thing
Doing them now. Will post all the answers soon.
Yes please! Please get solutions for Question 10 and 11 too! And yes question 11 was experimental design. Vague memory, but as far as I can remember it was something about lipase and enzyme activity and turning the alkaline solution neutral.
what did people put for what occurred to lead to the preservation of the animal from when the steppe Bisson died to when it was frozen? (4 marks)My worst question :( :(. Said something bout how animal is in cold temps. Body freezes. And how soft body parts also fossilise and bs'd that whole thing. Sad life.
For the thunderstorm asthma question, was the name of the cell- mast cell, and name of the protein- IgE antibody?oh no
oh no
would i have gotten any marks for B cell & antibody? because allergens bind to b cells to produce antibodies which then attach to mast cells :ll
My worst question :( :(. Said something bout how animal is in cold temps. Body freezes. And how soft body parts also fossilise and bs'd that whole thing. Sad life.The questions was, in my opinion, just outlining the steps of fossilation. I'd assume you'd have to state somewhere that the carcass has to be undisturbed (as in no predation or any natural occurrences affecting its position).
oh noWhat did the question ask specifically? I can't remember, but I think the appropriate answer was mast cells. I'm not too sure whether just antibodies would even be accepted (specifically, it should be IGE antibodies), but from recent exam reports, VCAA hasn't been extremely pedantic.
would i have gotten any marks for B cell & antibody? because allergens bind to b cells to produce antibodies which then attach to mast cells :ll
The questions was, in my opinion, just outlining the steps of fossilation. I'd assume you'd have to state somewhere that the carcass has to be undisturbed (as in no predation or any natural occurrences affecting its position).
What did the question ask specifically? I can't remember, but I think the appropriate answer was mast cells. I'm not too sure whether just antibodies would even be accepted (specifically, it should be IGE antibodies), but from recent exam reports, VCAA hasn't been extremely pedantic.The question asked for what is the name of the cell and protein that the allergen interacts with? That's what I remember but might be wrong. :-\
Is it fine if you just wrote IgE?
For the photosynthesis question, why was there high O2 conc. when the plant was photosynthesising in Region R(stroma) than when plant was not photosynthesising. Doesn't the splitting of H2O occur in thylakoid membranes to form O2 in light dependant stage? Then, how can O2 be in stroma?This question asked you to say why there would be a higher concentration of oxygen in the stroma when photosynthesis is occurring compared to when it isn't. You are right in saying that the formation of oxygen does occur on in the thylakoid lumen, but oxygen will diffuse into the stroma and increase the oxygen concentration during photosynthesis. However, oxygen will not be produced/diffuse into the stroma when photosynthesis is not occurring, hence why there is a higher concentration of oxygen during photosynthesis
For question 1 wasn't molecule 1 tRNA and molecule 2 DNA?That's exactly right - that's definitely a mistake in our solutions - we will edit it with the correct solution.
Hey,
Attached to this post is a pdf containing all of the suggested solutions written by me and Erutepa.
As always, feel free to question any of this if it doesn't make sense or you think we got something wrong. There were some questions (e.g. the one on bmp4) that were quite...open to interpretation. The solutions we've written are written as full paragraphs - this does not mean that you need to have written exactly the same thing as us to get the marks. They're just one possible way to write it - use them as a guide as to the type of information that was required.
In order to see and download the attachment, you need to be logged in.
I'll go through and answer the questions that have come up so far in a minute, I need to eat dinner first though haha
For question 1 wasn't molecule 1 tRNA and molecule 2 DNA?Sorry I should have had a coffee before I started writing. Have fixed it.
For question 10b in short answer, can you get the marks if you said that mtDNA mutates more often because of no repair mechanisms, therefore nuclear DNA is more representative of divergence to determine evolutionary relationships?While the higher mutation rate is a difference between the two, I don't think your justification is sufficient. Just because nuclear DNA has a lower mutation rate doesn't mean its necessarily better to determine evolutionary relationships. You might get away with saying that a lower mutation rate makes it good for tracing distant evolutionary relationships as mRNA may have possessed too many mutations to be used accurately, but I don't think I would consider the example given as distant evolutionary relationships.
Haha thats okay, for 8c. could temperature be considered a factor that affects the migration of DNA through the gel? (i.e at low temperatures the DNA may move very slowly)I think that would be a valid response!
Sorry I should have had a coffee before I started writing. Have fixed it.
How many marks was the table in the first question worth?2. You would have gotten one mark for each difference.
Thanks :)
with 9.c. would it be okay if you mentioned the scientist used Immunosorbent Assay test..You could say this, however its important that you explain how it only detects the constant region and that the constant region is essentially identical for all antibodies. It's the explanation that will get the mark - not stating the assay.
the test is conducted with the heavy chains which remain constant.. or something
Would histamines count as a protein if you didn't say IgE?The question wording indicates the protein involve interacts with the pollen fragments. Histamine doesn't really interact with the pollen fragments while IgE antibodies do. There is a chance they may award the mark if you said histamine, but I wouldn't be surprised if they take that as an incorrect solution, unfortunately.
Would heparin count for the chemical barrier question??I don't know what heparin does and I can't seem to find much about it on google. What does it do?
for 8a is PKU okay?Yeah that should be fine
i think i forgot to state the temperatures at each stage of PCR, would i lose all 3 marksdepends how strictly your markers are following their marking guide. It'll probably say that to give one mark for each step, but if you're lucky they'll give you a mark or two for getting everything else right without the temp.
Thanks
Would heparin count for the chemical barrier question??I haven't heard of this before but I have done some reading and it seems that it is a chemical (anticoagulant) that does have innate immune fuctions, however, it is released by innate immune cells in response to the identification of a pathogen.
I haven't heard of this before but I have done some reading and it seems that it is a chemical (anticoagulant) that does have innate immune fuctions, however, it is released by innate immune cells in response to the identification of a pathogen.
The question asked for chemical barriers that would stop a pathogen before immune cells are aware, so I would say this response is incorrect.
For question 4)c. wouldn't a vaccine not be possible for pollen fragments? Because pollen fragments are allergens rather than pathogens, it is unlikely an immune response will be initiated against them in a normal individual as they will are ordinarily harmless molecules. Therefore, it no memory B cells or specific antibodies would be produced so long-term immunity could not be achieved?Allergens (such as pollen fragments) are just antigens. Ideally, people wouldn't mount an immune response to them as they would recognise them as benign antigens and thus an adaptive immune response would not be activated and IgE antibodies wouldn't be produced. However, this is not always the case, as the allergen antigens do illicit an adaptive immune response hence by IgE antibodies are produced and hence why people have allergic reactions to pollen and other allergens. As such, a vaccine can be made to allergens which operate as explained in the sample solution.
hi for question 6c it gave us the mRNA sequence so i wrote out all the complementary bases for that mRNA sequence and then found the corresponding amino acid for each codon. were we supposed to do that or were we supposed to find the amino acids using the codons in the mRNA sequence given to us?Codons are the 3 base groups on the mRNA. By writing out the complimentary 3 base codes, you are finding the anticodons. The chart gave which codons correspond to each amino acid, thus you should be using the mRNA sequence
would a systematic error be incorrect calibration of temp of test tubes and water bath therby affecting the whole lot of resultsYes!
For the limitation questions, would the absence of a control group be a limitation?I don't think there is much use for a control group (such as one at room temperature) so I don't think that would improve the experimental design - I could be wrong though.
(q11)
hi for the mc question about the bacteria that were modified to produce human insulin i chose GMO bc in the question it didnt specifially state that the bacteria had a gene from the human inserted into, it just stated that it was modified to produce human insulin so wouldnt GMO be more correct??I think you are supposed to infer that the bacteria must have contained a human gene in order to produce human insulin
Just a general question: How strict is the marking going to be.Based on most people saying that the exam was relatively straightforward I am guessing the will be probably the usual strictness or maybe a bit more strict (although this will always be question/assesor dependent).
What are peoples predictions??
hi for the mc question about the bacteria that were modified to produce human insulin i chose GMO bc in the question it didnt specifially state that the bacteria had a gene from the human inserted into, it just stated that it was modified to produce human insulin so wouldnt GMO be more correct??IIRC that option actually stated "genetically-mutated organism" so it would have been incorrect
I wrote along the lines of...You'd get some marks but I don't think you'd get all of them. And yeah, we hated it too.
The mutation of the gene BMP4 results in the changes in the intensity, duration and the times of the gene being expressed during embryonic development. And variation in these factors result in morphological changes, if there is a lot of variation it results in different phenotypic variation.
Phoenix is this right?
the question was question was quite stupid in my opinion.
Just a general question: How strict is the marking going to be.I get the feeling that for a lot of the 3 and 4 mark questions, a lot of people are going to get at least 1 or 2 marks respectively, but not many people are going to get full marks. It did seem like a bit of a change from previous years where for some questions it was relatively easy to get all the marks and for others the average mark was very very low. I don't think there'll be too many questions with extremely low average marks this time around, but I also don't think there'll be too many of those questions that have an average mark 2.3/3 or higher either.
What are peoples predictions??
Based on most people saying that the exam was relatively straightforward I am guessing the will be probably the usual strictness or maybe a bit more strict (although this will always be question/assesor dependent).
if bio scales down this year because of this X_XIf bio does scale down (which is unlikely) the difficult of exam/marking of the exam won't be the reason for this.
How can a vaccine for an allergen be produced? in relation to question 4.. We don't get vaccinated for a peanut allergy, so why is any other allergen different? So confusednot everyone will be susceptible to produce an allergic response towards peanuts thus no need for vaccination for everyone (the body does not detect it as something they need to produce an immune response against).
How can a vaccine for an allergen be produced? in relation to question 4.. We don't get vaccinated for a peanut allergy, so why is any other allergen different? So confusedThere was actually vaccine trials last year (and i believe they continued this year) for a vaccine against grass pollen.
Hi guys-Maybe. Depends how strict the examiners are being, it says actions "a person can take" - desensitisation requires medical supervision generally.
couple of quesions
Could you say desensitisation for 4b as a method of dealing with thunderstorm astham
-Did u have too specific the anitbody as Ige for 4A
-Did you have too say both Homo heidelbergisis and Homo Saipen for 10c
-Could you say that the fossil evidence found was not distinctive of a unique hominin group morphologicaly therefore was not sufficient by itself to suggest another hominin group for 10A
-Could you say the Nuclear DNA is better than mtDNA for this comparison as it provides mor genetic information for comparions compared too mtDNA
-Could you say the type of gel in use for 8c would vary the seperation of DNA fragments
SORRY FOR THE CRAP TON OF QUESTIONS highkey pissing myself rn
Thanks
The explanation I wrote for that question is one that it'd be reasonable for you to make in vce - you could trigger an immune reaction using pollen fragments which would mean that then when thunderstorm asthma occurred, you'd get B memory cells making antibodies that bind to the pollen which prevents them from crosslinking the IgE antibodies on mast cells instead - sort of like how anitbodies can cause agglutination of snake venom.I still can't see how it can be possible to create a vaccine for an allergen, because the allergen from the vaccine would still create IGE antibodies, which are already bound to mast cells, so if a vaccine containing and allergen is introduced, then wouldn't the body just be making more IgE antibodies (which actually does the complete opposite of what vaccines are supposed to do)? Or am I thinking of it wrongly?
I still can't see how it can be possible to create a vaccine for an allergen, because the allergen from the vaccine would still create IGE antibodies, which are already bound to mast cells, so if a vaccine containing and allergen is introduced, then wouldn't the body just be making more IgE antibodies (which actually does the complete opposite of what vaccines are supposed to do)? Or am I thinking of it wrongly?They're altered like how other pathogens are altered, except in this case it's so that they can't crosslink (or at least that's what they're doing for the grass pollen vaccine).
for question 2ai could u hv written NADPH and ATPThey get used and reused in photosynthesis - there's no need for them to be diffusing into the chloroplast.
They're altered like how other pathogens are altered, except in this case it's so that they can't crosslink (or at least that's what they're doing for the grass pollen vaccine).
- And I still don't understand the thunderstorm asthma vaccine question? Vaccines are used to trigger an immune response, but with this scenario, an immune response is already occurring?
I haven’t seen the question but regarding how a vaccine against a allergen could work.That makes sense.... lol I'm screwed then
The pollen would be attenuated so it had low reactivity with IgE antibodies (they wouldn’t be able to bind = no mast cell degranulation). However, our immune response would still build up non-IgE antibodies to the pollen antigen. Therefore, when the individual is exposed to the real pollen the pollen specific memory B cells would be able to very quickly produce antibody and sort of neutralise the pollen, preventing any IgE antibodies that are produced from binding as the IgG antibodies have already bound. Much like how you can neutralise a virus by binding antibody and preventing it from interacting with host cells.
I’d doubt they would expect you to describe such detail but I thought I’d share for interest.
-Could you say the type of gel in use for 8c would vary the seperation of DNA fragmentsDepends how you phrased it e.g. concentration of agarose in the gel can lead to different sizes in the pores -> different separation.
Do you have any idea what would be a good exam score for 45 plus this year with high sac scoresBased off previous years you'd need about 90% for a 44 (with equivalent SACs). It's unlikely to change much this year.
1. For the last question(limitations), can you say that a limitation was that the three students didn't do it in the same time of day?1. Unlikely that would have any affect on the experiment given temperature was measured.
2. And I still don't understand the thunderstorm asthma vaccine question? Vaccines are used to trigger an immune response, but with this scenario, an immune response is already occurring?
3. For question 1b, can you say that there are over 300 monomers because of how one amino acid is coded for by 3 monomers, therefore 10x3=300 and 6 monomers for START and STOP codons?
4. For 3a, can you say entry via mouth or nose if pathogen has airborne or droplet transmission?
5. For 3d, did you have to specify MHC Class II receptors?
6. For 5c, did you have to specify advantageous phenotypes-natural selection,etc.?
7. For 6aii, can you say chromosomes in WBC?
8. For 8c, can you have said the time that the gel was left on for? Cos if the gel is left on for too long, then all the fragments will settle at the bottom?
9. For 9a, can you say the use of public toilets as a social/economic factor?
10. For 10b, can you say nuclear DNA can be used for DNA hybridisation, wherease mtDNA cannot?
I'm so sorry for so many questions! Don't really think I did too well, after looking at the answers :(
I’ve also seen this explanation online about allergen vaccines, and it is what I used in the exam. Do you think it could work, even though it’s not explained as much at the cellular level like you did?That type of desensitisation is called a vaccine in some areas, but I don't think it would be considered a vaccine based on the definition used in VCE.
I said that vaccines can be made by exposing allergy sufferers to small amounts of the pollen antigen, in a bid to slowly desentise the body the allergen by basically making them more tolerant the substance so the immune system recognises it as a harmless substance.
What was the answer to the limitation question?
I said that the temperatures that they didn’t have enough temperatures to work with and should repeat the experiment with different temperatures
I said that they had no control group.
For SA Q11, the one that was asking about possible reasons leading to the two isolated errors of student 2's measurements, which were random errors, was it okay to write human errors, like incorrect measurements of components and starting the timer later? Are human errors random errors?Yep human errors are fine. Random errors are ones that pop up in random parts of the experiment, rather than consistently across the whole thing.
for 4c, wouldn't providing a low dose of an allergen in the form of a vaccine be dangerous as the allergen would bind to the antibodies on the mast cells and cause then to release histamines? Isn't that why people take antihistamines?4c. Nope. Allergens can be modified so that they can trigger an immune reaction but not bind to IgE (like how pathogens can be altered to not cause disease).
For 7b, could the answer possibly be that the reason bissons became extinct is from overhunting from humans
could an option for 11e be that the solutions were not measured with accurate measuring materials improve by measuring with micropipette
What study score would be equivalent to around 86-87% in SACS and exam?Assuming no scaling to sacs, probably around 40ish.
In the pdf, the answers for 6dii, was it a frameshift mutation, or just a point substitution?6dii. Asked about a deletion, so it was a frameshift mutation. 6di. was a point substitution.
"the use of chemical agents against pathogens including the distinction between antibiotics and antiviral drugs with reference to their mode of action and biological effectiveness."Yeah I thought that question was unreasonable. It could be expected that you know about the ways in which antibiotics work (covered under "mode of action") but I don't think it's fair to expect you to know how penicillin specifically works - antibiotics can work in multiple ways, including disrupting cell membranes and protein synthesis, which were both other options (although not worded like that). If only one of the answers was something that any antibiotic does then I'd say it's fine, but that wasn't the case with that question meaning that it did require you to know about penicillin specifically.
can you infer from this that you should have to know specific antibiotics and their mode of action, or just have a rough idea overall. Multiple choice question on penicillin got me fuming
Yep human errors are fine. Random errors are ones that pop up in random parts of the experiment, rather than consistently across the whole thing.
What study score would be equivalent to around 86-87% in SACS and exam?You're looking at around a 41 especially since the exam's A+ cut off will be higher than last year's. Last year you would have gotten around a 42 and maybe even a 43.
what if you wrote time for the limitation question and said you could use a digital timer which could be more accurate than humans stopping the stop watch?Limitations are disadvantages of experimental desgin that impair its ability to identify the effect of the IV on the DV. For this experiment, a limitation would be anything that impairs our ability to say that increase temperature decreases the time taken for neautralisation to occur. An inaccurate timing method could be a limitation as if the timing method gave inconsitant times the experiment's ability to accurately test the relationship betwen the IV and the DV is flawed. I would however be reluctant to use this as a limitation since I don't think using an automatic timer (I assume this is what you mean by digital) is able to be applied to this experiment. However if you justified it properly, you might be awarded the mark, depending on how strictly thay mark the question.
Would it be accurate to say this: Nuclear DNA is made with crossing over from meiosis which therefore suggests that it contains genetic information from the mother and father of the organism. According to this theory, scientists prefered nuclear DNA because it can show whether the young girl (referred to in the article) in fact was the product of interbreeding between Denisovans and Neantherals thereby providing information into the history of Denisovans which mtDNA cannot as it does not have recombinant DNA from the parents.
Haven't read the question but:Regardless, it still implies that interbreeding must have occurred
Crossing over in meiosis doesn't cause the DNA to be from two parents but it does mean that DNA from 2 parents can be found on the one chromosome.
Regardless, it still implies that interbreeding must have occurred
What study score should I expect with unit 3 sacs at 85%, unit 4 sacs at 81% and exam at 80%ish ? assuming no scaling of sacsAround a 40 or high 30s with no scaling of sacs imo
For question 6di, I recall that it was a substitution in the 12th nucleotide of the mRNA codon, and that they both coded for leucine regardless... correct me if I'm wrong. And for question 11e, would it be appropriate to state that it was difficult to determine the exact time at which the pH became neutral, and hence using a more sensitive pH probe is required.6di actually stated a that the twentieth nucleotide changed to uracil. This would change the amino acid that the codon coded for from glycine to valine.
Thanks
Also, for question 11 did you have to exclusively state that the measurements were too low or could you just state them and then explain the errors... and if I'm rank 1 and got around 88% on exam, what study score should I get??
Also, for question 11 did you have to exclusively state that the measurements were too low or could you just state them and then explain the errors.Is this for 11c? The question just asks you to identify the errors and give two examples of sources of errors, so you should be fine to just name them without justifying why they were the ones with errors.
With around 88% sacs and 80/75% on the exam what study score could I get (before scaling)?High 30s, maybe 40.
Use this as a mild reference and assume an A+ is 83% for 2019A+ cutoff is very unlikely to be that high.
does anyone have an idea of the study score id get if im averaging 88% on sacs and 84% on exam?Likely in the area of 39-42 dependent on how your SACs scale.
Hello I ranked 1 with sac average of around 98%. I think I got around 85-90% on the exam. Would anyone be able to predict study score around about? :)44-46 imo
A+ cutoff is very unlikely to be that high.
Tho I thought the exam was fairly straightforward in everyone's opinions and everyone seemed to do well? What do you reckon
For question 4.c, I said stated that a vaccine would be ineffective, as a vaccine would just produce more IgE anitbodies that would prime more mast cells to heighten the allergic reaction, as more histamine is released. Would this be considered wrong?It's possible that either yes or no will be accepted with appropriate justification. If that is the case, this explanation may be accepted.
Tho I thought the exam was fairly straightforward in everyone's opinions and everyone seemed to do well? What do you reckonPeople did seem to find it easier and I won't be at all surprised by the cutoff going up, I just don't think it'll go up that much - the cutoff has never increased by that much in the years since 2013 when the exam format changed.
With question 8c. I said size of fragment, charge of fragment and contamination from other dna. Would those answers be acceptable. And for 8d, ethical issue was who has right to the information and privacy of the patient. Are they acceptable?
You will get a mark for the first factor - However I think the other two factors listed would be marked as incorrect
Contamination by other DNA isn't a factor that affects DNA's movement. It will affect the banding pattern, but the movement of DNA through the gel will be unaffected.
All DNA has the same mass:charge ratio, which essentially means that all DNA will experience the same force in an electric field - regaurdless of the magnitude of the DNA's charge charge.
Does anyone remember the exact phrasing of Question 8c); the one about the 3 factors affecting DNA movement in gel.There wasn't anything too specific in the phrasing, the three factors just had to affect the movement of dna fragments through the gel.
And for 8d, ethical issue was who has right to the information and privacy of the patient. Are they acceptable?You'd probably get the mark for that. The question does ask about ethical implications arising "from this finding" but it seem like the finding being referred to is that a couple has the same mutation - so I don't think the issue would have to do with a fetus/potential fetus directly.
Wouldn’t charge be a factor that allows DNA to migrate across the gel? It doesn’t vary between DNA but it is still valid i think.It's possible that it could be accepted. The way the question is phrased implies that it wants things that affect how dna goes through migration, not things that effect whether it will migrate. I'm not sure if vcaa will make that distinction though. By asking for things that affect its migration, you're implying that migration occurs - the presence of charge only ensures that it does occur, and may therefore be irrelevant.
Does anyone remember the exact phrasing of Question 8c); the one about the 3 factors affecting DNA movement in gel.It was "Discuss three factors that affect the migration of DNA fragments through the agarose gel during gel electrophoresis."
It was "Discuss three factors that affect the migration of DNA fragments through the agarose gel during gel electrophoresis."
Overloading of DNA - overloading of DNA slows down the migration of DNA fragments. Contamination - presence of impurities, such as salts or proteins can affect the movement of the DNA - about the dna migration questionI don't disagree with this, however simply stating "contamination with other dna" I don't think will earn you the mark unfortunately. DNA overloading may very well affect the movmenr of DNA, but contamination with other dna and DNA overloading aren't the same thing, and for that reason I don't think it's suffice to use dna contamination as a factor affecting movement of DNA.
Can someone predict my study score, If I'm averaging 91% in SACs, and I'm rank 4 in my cohort (highly competitive, select entry school w 100+ bio students) and I get 90-95% on the exam?Likely 45+ (assuming your exam prediction is accurate). Can't predict it any more accurately than that given the limited data vcaa provides, anything else would just be guessing.
Hey i have some questions.. Would you be able to tell me if these could be right?1a) This was a table, if you wrote about uracil in the box for tRNA difference 1 then you would have had to write about thymine in the box for dna difference 1.
1a) As a difference, i wrote that tRNA has uracil as a nucleotide base. I didnt write it as a comparison stating that tRNA has a uracil base instead of thymine. Is that okay?
3a) For the entry of bacteria.. i wrote that it could enter orally by contaminating food, or through inhalation since its airborne. Would this be right?
6ai) For examining the blood sample, i wrote that they could check the persons chromosomes.. since it is a chromosomal abnormality.
7b) For the extinction, i wrote that lack of diversity can lead to extinction when exposed to new selection pressures.
8c) For the gel, i wrote factors could be charge, size (shorter fragments will move further) but also weight (stating that heavier bands will stay closer to the well while lighter will be lighter).
9a) As a social factor, i wrote having pets. Hence, this could increase physical interactions and allow transfer.
I would really appreciate it if you could let me know about these answers!
Could someone do a study score estimate: I'm in a strong cohort of about 60.
GA1: Rank 25
GA2: Rank 15
GA3: 81/85/90%
Thanks :D
I think 26-31 study score
Dunno about that mate
Hello Eurepta and Phoenix!This question is one of those ones where the precise wording can trip you up.
For Q31, I did a bit of research on the capsule of Influenza and found this:
Influenza is an RNA virus with a roughly spherical lipid envelope, which is colored yellow on our schematic model. The outside of the virus capsule is covered with 3 specific proteins: hemagglutinin (purple), neuraminidase (pink) and the M2 channel (blue).
For this reason, could Q31 be C given this information? A mutation in the capsule could change the neuraminidase protein.
Hi just a quick quick question
for the genetic screen one should these be okay.
Ethical issue: the baby's right not to be tested
Social issue: The screen becoming 'free' in the future would mean use of taxpayers money, it may affect the economy
I know someone with the similar ranking and B+ on the exam who got 28 soExam is far more important than ranking. Similar rankings can mean vastly different things between schools, just knowing someones rank is meaningless without context. All of those exam marks will be in the A+ range (potentially with the exception of 81%). There's no way they'll get anything remotely close to 28 with that.
Could someone do a study score estimate: I'm in a strong cohort of about 60.81% will be approximately a 40, 90% will be approximately a 44, assuming equivalent GA1 and GA2 scores. If your GA1/2 scores are lower than your exam (your position as a percentile, not the actual score) then they'll go down a bit, if they're higher then they'll go up a bit. Your GA1 is likely to be a little lower, your GA2 will probably be somewhat equivalent to your exam (depending on what score you got) - but that can't really be predicted without knowing how your cohort did on the exam.
GA1: Rank 25
GA2: Rank 15
GA3: 81/85/90%
Thanks :D
Hi just a quick quick questionThe baby wasn't being tested - both parents carrying the same recessive trait does not mean that the baby will inherit it. You wouldn't get the mark for the social one either because it's not relevant - the question asked about a social issue resulting from the finding that both parents/prospective parents carried the same mutation.
for the genetic screen one should these be okay.
Ethical issue: the baby's right not to be tested
Social issue: The screen becoming 'free' in the future would mean use of taxpayers money, it may affect the economy
I know someone with the similar ranking and B+ on the exam who got 28 sothink about that exam score, clearly an A+ which only 10% of the state get. Do u really think that equates to a 28-31?
think about that exam score, clearly an A+ which only 10% of the state get. Do u really think that equates to a 28-31?
would it be fine to say with the ethical or social factor in the Zika virus question that hunting of animals could be one, since it involves touching the animal?Yep. Anything that fits under ethical or social and involves coming into contact with animals should be fine.
think about that exam score, clearly an A+ which only 10% of the state get. Do u really think that equates to a 28-31?I believe that this was an incorrect prediction as a person's exam results can drastically affect their overall score. It depends year by year, but a B+ on the exam typically places them much lower on the scale than a person with an A+ - just keep Phoenixx's prediction in mind as a more accurate guess and try not to stress. :)
For the question about steps in fossilisation... I kind of panicked and stated the build up of sedimentary layers allows hard Boney parts to be preserved... Which isn't relevant. I included all other appropriate info based on the question. Will I still receive any marks?I kind of did the same tho I said after sediment it is covered by snow, so I hope it i get a mark. Also adding on if you said there needed to be lack of scavengers is that fine (there could be snow wolves or anything)?
For the question about steps in fossilisation... I kind of panicked and stated the build up of sedimentary layers allows hard Boney parts to be preserved... Which isn't relevant. I included all other appropriate info based on the question. Will I still receive any marks?You won't lose marks for incorrect answers in vce. You'll still get marks if your other parts were correct.
what if I wrote for the genetic mutations in couples question that the ethical issue was data maybe not be secure, is that fine? and for the social, I wrote the couple may decide not to have kid leading to them becoming unhappy? is that fine?The first one should be fine, the second one will depend on what they consider a social issue - choosing not to have a kid/alternative methods of having children should count but I'm not sure if they'll accept your justification as a social issue (I reckon you'd probably get the mark for it though).
For 2b, I wrote that both NADPH and ATP act as energy carriers, and that NADPH transfers the Hydrogen, would the first part be accepted?Yeah calling them energy carriers should be fine.
Also does anyone have the marks for each question? Trying to work out an estimated percentage but unsure of what each question is worth
For MC 37The question asks us to use the graph as well as knowledge from the course to determine which statement is correct.
(The question showed a graph and asked what a benefit of Bt corn is.)
couldn't the answer also be Bt cotton cost less as less herbicide was used? Plz help
The question asks us to use the graph as well as knowledge from the course to determine which statement is correct.
While we can tell (from the graph) that there would be less herbicide costs for Bt corn (as Bt corn is associated with lower herbicide use) - we, however, don't know how much it costs to buy the Bt seed compared to the non-Bt (or anyother related costs). As such, we cannot say that Bt corn costs less than non-Bt corn.
The only valid statement is that negative impacts on the environment will be reduced (since Bt corn is associated with lower herbicide use shown in the graph)
I see we you are coming from, but negative impact on the environment can also be increased from using Bt corn (as a super weed could be formed and a reduction in genetic diversity in the Bt corn population would occur)There's no indication of this in the graph though. All the graph says is that as Bt corn is used more, herbicide is used less. The only option that definitely will happen as a result of less herbicide is less damage to the environment from that herbicide. It's possible that costs will also decrease, but you don't have enough information in the graph to conclude that they will decrease.
There's no indication of this in the graph though. All the graph says is that as Bt corn is used more, herbicide is used less. The only option that definitely will happen as a result of less herbicide is less damage to the environment from that herbicide. It's possible that costs will also decrease, but you don't have enough information in the graph to conclude that they will decrease.
the graph also doesn't have enough information to conclude that the use of Bt corn will decrease environmental impactThe questions says to use the information in the graph and your knowledge from the course to choose a valid statement.
For the photosynthesis question, why was there high O2 conc. when the plant was photosynthesising in Region R(stroma) than when plant was not photosynthesising. Doesn't the splitting of H2O occur in thylakoid membranes to form O2 in light dependant stage? Then, how can O2 be in stroma?
O2 is produced in the thylakoid membrane but during photosynthesis (i think) it needs to diffuse out of the cell and into the atmosphere that's why it would have a higher concentration in the stroma as O2 diffuses out.
that's what i send anyway
My general knowledge is telling me the farmer would use the Bt corn if it was profitable, if it was not profitable he would not use it, therefore I think it is a safe assumption that the Bt corn is cheaper than the non-Bt corn.I think it's been established that the common answer is the one given by both Erutepa and PhoenixxFire, multiple times. If you're correct, you will be able to discover that when VCAA releases the 2019 answers. There's no point wasting any more time debating on hypothetical semantics here.
My general knowledge is telling me the farmer would use the Bt corn if it was profitable, if it was not profitable he would not use it, therefore I think it is a safe assumption that the Bt corn is cheaper than the non-Bt corn.This logic isn't necessarily true. For Bt crops to be profitable, they don't need to be cheaper to produce than non-Bt crops. Bt crops may very well be more expensive to produce, however will return larger crop yields and thus turn a larger profit - making them profitable. As such, with the information from the graph and the content in the course - as well as logic - we still cannot say if Bt crops cost more than non-Bt crops.
Does anyone have a copy of the 2019 bio exam? :D :DUnfortunately the exam can't be shared via the forums until after VCAA shares it themselves due to copyright.
I need it to refresh my memory on some of the questions i think i didn't get 100% on. Thnx guys
Hey so for the zika virus question about things the government can do to reduce its spread, how many marks would I get ffor this:You potentially wouldn't get the mark for the second one - the stem of the question suggests that zika first appeared in humans as a result of a mosquito transferring it from monkey to human, however this does not mean that this is still a mode of transmission - viruses have frequently appeared in animals first and then mutated to allow them to be transmitted to humans, it's possible that a mutation is what allowed it to infect a human in the first place and that all subsequent infection is human to human via mosquitos. - I don't know whether this is true for zika specifically, but the first line of the question which states that it's most commonly transferred from person to person via mosquitoes appears to support this.
1) eradicate mosquito populations known to carry the Zika virus
2) cull or isolate animals (monkeys) known to carry the Zika virus
3) study the structure of the zika virus and using rational drug design, produce an antiviral drug and administer it to those with the Zika virus.
For the steppe bison fossilization question, how many marks /4 would I get for this?
- Bison dies and falls in water which freezes rapidly, trapping the bison in an ice block (i couldn't think of anything else don't judge lmao)
- cold temperatures and lack of oxygen reduce rate of decay by bacteria. Low temp reduces kinetic energy and therefore frequency of successful collisions between enzymes and substrates that cause decay of soft tissue
- bison is protected from scavengers
- this preserves both soft and hard tissues of the bison
- over many years, the ice melts away, exposing the bison to allow scientists to discover the fully intact fossil.
For the steppe bison fossilization question, how many marks /4 would I get for this?That should be fine. It would have been good to also include that there wasn't any changes to the climate of the area that would have allowed it to thaw, but given your last line says what happens when it melts, that's probably enough to convey that it was frozen the rest of the time.
- Bison dies and falls in water which freezes rapidly, trapping the bison in an ice block (i couldn't think of anything else don't judge lmao)
- cold temperatures and lack of oxygen reduce rate of decay by bacteria. Low temp reduces kinetic energy and therefore frequency of successful collisions between enzymes and substrates that cause decay of soft tissue
- bison is protected from scavengers
- this preserves both soft and hard tissues of the bison
- over many years, the ice melts away, exposing the bison to allow scientists to discover the fully intact fossil.
For the steppe bison fossilization question, how many marks /4 would I get for this?
- Bison dies and falls in water which freezes rapidly, trapping the bison in an ice block (i couldn't think of anything else don't judge lmao)
- cold temperatures and lack of oxygen reduce rate of decay by bacteria. Low temp reduces kinetic energy and therefore frequency of successful collisions between enzymes and substrates that cause decay of soft tissue
- bison is protected from scavengers
- this preserves both soft and hard tissues of the bison
- over many years, the ice melts away, exposing the bison to allow scientists to discover the fully intact fossil.
Sorry if I am being ignorant but does anyone have the actual exam from 2019 VCAAUnfortunately VCAA have not yet published the exam and as such sharing copies of the exam on the forumns is copyright infringement and against forum rules.