Post by: Joseph41 on October 09, 2018, 03:26:41 pm
(https://i.imgur.com/AgeDlC5.png)
This thread is for all exam-related discussion. Was it easy? Was it hard? What did you get for each question? Feel free to post any and all of your thoughts below.
If you don't have an ATAR Notes account yet, no stress - you can register for free here!
You can find the exam solutions by vox nihili and PhoenixxFire here!
Post by: Scribe on November 02, 2018, 12:00:08 pm
Post by: O2square on November 02, 2018, 12:04:11 pm
Post by: vox nihili on November 02, 2018, 12:11:37 pm
PhoenixFire and I will do answers as soon as we can get our hands on a copy of the exam!
Post by: PhoenixxFire on November 02, 2018, 12:13:41 pm
What sort of things were in it? Did they do a bit more on immunity this year?
Post by: Yacoubb on November 02, 2018, 12:14:36 pm
Already hearing that was a pretty tough/odd exam from a few sources. That's good news if you also thought it was tough. Remember, your exam score is whatever your performance was RELATIVE to everyone else. So hard exam means lower scores are fine :)
PhoenixFire and I will do answers as soon as we can get our hands on a copy of the exam!
Hearing this too! Will be doing some corrections for my students too so hopefully we can get our hands on a copy of the exam soon!
Post by: benmcleod on November 02, 2018, 12:24:45 pm
I heard something about a Botox question?
What sort of things were in it? Did they do a bit more on immunity this year?
yep, botox as a protein (enzyme?) inhibitor, 1Mark question of how this would happen. 3Marks: secondary doses don't last as long as the first dose, explain. I treated it like a vaccination question in a way, so hopefully that worked.
Post by: crawlingvines on November 02, 2018, 12:27:28 pm
yep, botox as a protein (enzyme?) inhibitor, 1Mark question of how this would happen. 3Marks: secondary doses don't last as long as the first dose, explain. I treated it like a vaccination question in a way, so hopefully that worked.
I did the same thing, woo!
Post by: Maya24 on November 02, 2018, 12:29:56 pm
Post by: PhoenixxFire on November 02, 2018, 12:31:08 pm
I found the exam easier than last years. All the questions were doable.That’s awesome! Great job ;D
Post by: Erutepa on November 02, 2018, 12:35:06 pm
What did people write for the question asking to predict two structural features?My friend was laughing (not literally) because he was randomly reading about that species (whatever it was) and knew its characteristics quite well.
Post by: Anne Boleyn on November 02, 2018, 12:35:52 pm
yep, botox as a protein (enzyme?) inhibitor, 1Mark question of how this would happen. 3Marks: secondary doses don't last as long as the first dose, explain. I treated it like a vaccination question in a way, so hopefully that worked.I wrote that memory T cells form would that be wrong or did I have to specify memory B cells ??
Post by: benmcleod on November 02, 2018, 12:37:52 pm
What did people write for the question asking to predict two structural features?
1. Wide, broad feet: allow better movement on sand and swimming ability, ( I assumed it was some kind of half whale half hippopotamus amphibian.)
2. I think i said something about a vestigial pelvis?
If you google ambulocetus you can see the actual animal, but i think that's irrelevant as long as the features you proposed and the explanations were reasonable.
Post by: vox nihili on November 02, 2018, 12:38:08 pm
My friend was laughing (not literally) because he was randomly reading about that species (whatever it was) and knew its characteristics quite well.
Probably the worst tangent I ever went on this year with my tutoring students was to talk about the way that headlice and pubic lice are different species and that they'd evolved to latch onto different hairs. Nek minit they had a whole SAC on it the next day :')
Post by: benmcleod on November 02, 2018, 12:40:45 pm
I wrote that memory T cells form would that be wrong or did I have to specify memory B cells ??I'm not sure how memory T's work, but given the botulinum toxin will be injected, I would assume you needed to talk about the Humoral response? Not sure, depends how specific they require the answer to be.
Post by: Hirul1280 on November 02, 2018, 12:42:00 pm
Post by: Bri MT on November 02, 2018, 12:44:10 pm
My friend was laughing (not literally) because he was randomly reading about that species (whatever it was) and knew its characteristics quite well.
In my exam there was a question about tortoises & I spent a lot of my childhood learning about them out of personal interest.
Usually that prior knowledge doesn't make too much difference, but it's a good mood-booster
Post by: briv01 on November 02, 2018, 12:56:41 pm
Post by: AISHAB on November 02, 2018, 12:57:47 pm
1. Wide, broad feet: allow better movement on sand and swimming ability, ( I assumed it was some kind of half whale half hippopotamus amphibian.)
2. I think i said something about a vestigial pelvis?
If you google ambulocetus you can see the actual animal, but i think that's irrelevant as long as the features you proposed and the explanations were reasonable.
Could we have also said flippers enables them to swim in water and catch prey
Legs similar to those of ancestral land mammals, enabling them to quickly run away from predators.
Post by: briv01 on November 02, 2018, 01:00:47 pm
Post by: gab.r_se on November 02, 2018, 01:01:26 pm
Post by: gab.r_se on November 02, 2018, 01:01:52 pm
I said flippers enabled them to swim and catch prey/ swim away from predators
I did that, too.
Post by: HighSchoolerRS on November 02, 2018, 01:02:02 pm
Post by: gab.r_se on November 02, 2018, 01:05:35 pm
Post by: gab.r_se on November 02, 2018, 01:06:19 pm
I talked about cell mediated immunity for the botox question because I thought that it was in the muscle cells, which is how they were being inhibited...
I did the same thing.
Post by: gab.r_se on November 02, 2018, 01:06:59 pm
Post by: briv01 on November 02, 2018, 01:09:19 pm
Social- less cost for farmers to buy insecticides
Biological- allergies for workers
And for the gmo
Social- less cost to buy Vit B supplements as it combats the vit deficiency
Biological- gmo moving from a controlled to natural environment where it can breed with wild rice and cause loss of variation
Post by: benmcleod on November 02, 2018, 01:11:30 pm
I talked about cell mediated immunity for the botox question because I thought that it was in the muscle cells, which is how they were being inhibited...Damn, I think you're right. I guess both could be accepted as the initial injection may meet some humoral response, hence lessening the amount of toxin reaching the cells, although cell-mediated is certainly more correct.
Post by: benmcleod on November 02, 2018, 01:13:03 pm
What you guys say about the question where there is excessive cell deathI talked about cytotoxic T cells, as I thought they were leaning towards autoimmune diseases.
Post by: AISHAB on November 02, 2018, 01:14:15 pm
How did you guys find multichoice?
Post by: benmcleod on November 02, 2018, 01:15:56 pm
Does anyone remember what the said the hypothesis Elsa was testing was?That algae with x pigment had higher rates of photosynthesis under green light than algae without x pigment?
Post by: Erutepa on November 02, 2018, 01:16:18 pm
I talked about cell mediated immunity for the botox question because I thought that it was in the muscle cells, which is how they were being inhibited...Since it is a toxin, I think they want you to talk about the humoral immune system rather than the cell mediated as toxins can be neutralised by antibody binding.
Post by: briv01 on November 02, 2018, 01:16:58 pm
Does anyone remember what the said the hypothesis Elsa was testing was?
How did you guys find multichoice?
Multiple choice was pretty good in my opinion, I said she that the test tube with the red algae will have the highest rate of photosynthesis and turn yellow as a result
Post by: AISHAB on November 02, 2018, 01:18:58 pm
Multiple choice was pretty good in my opinion, I said she that the test tube with the red algae will have the highest rate of photosynthesis and turn yellow as a result
Yeah same
Post by: briv01 on November 02, 2018, 01:20:52 pm
Post by: gab.r_se on November 02, 2018, 01:49:14 pm
What did you guys say for the very last question about the other variables affecting the results
I said something about cellular respiration, but I don't know if that's right.
Post by: gab.r_se on November 02, 2018, 01:50:50 pm
Post by: benmcleod on November 02, 2018, 01:51:50 pm
What did you guys say for the very last question about the other variables affecting the results
Red pigment could leach out of the algae, causing the solution to appear more red than it actually is and hence inaccurate results.
Initial CO2 concentration of green algae may have been higher than red algae, making it appear that less CO2 was used in this test.
I found this question hard, and initially talked about different rates of cellular respiration but ruled that out due to the dark control test. I'm not sure if either of those answers are right.
Post by: benmcleod on November 02, 2018, 01:53:00 pm
For the experiment question, weren't there red algae balls and green algae balls? I hope I didn't misread the question... There were no transparent balls, right?No transparent balls. Both balls had the same clear jelly medium, the algae itself was either a green or a red species.
Post by: briv01 on November 02, 2018, 01:56:43 pm
Red pigment could leach out of the algae, causing the solution to appear more red than it actually is and hence inaccurate results.
Initial CO2 concentration of green algae may have been higher than red algae, making it appear that less CO2 was used in this test.
I found this question hard, and initially talked about different rates of cellular respiration but ruled that out due to the dark control test. I'm not sure if either of those answers are right.
Yeah I said the initial Co2 of the two test tubes may not have been controlled so the results won’t have been accurate as they might have started off with different Co2, this makes Co2 another IV
I also said this about the temp of each test tube as the temp affects enzymes that run photosynthesis
Post by: LifeisaConstantStruggle on November 02, 2018, 01:57:38 pm
Just asked my students about their opinion on their exam and the difficulty (estimated anyways) is between the 2017 exam and the 2018 NHT one. So it's fairly tough. But results are relative anyways so you'll never know.
If you think you're not doing bio in the future. Great. Because you can now slowly forget everything about bio until your knowledge disintegrates into feeble expressions related to the subject like how the mitochondria is the powerhouse of the cell and how the only thing that can both be smooth and rough in bio is the endoplasmic reticulum (not sure if 100% true).
Good luck for your future exams and endeavours!
Edit: Please don't forget about biology though was a joke it is very intellectually stimulating
Post by: zakaria-03 on November 02, 2018, 02:22:09 pm
Post by: Yacoubb on November 02, 2018, 02:25:07 pm
Does anyone have any suggested anwsers?????
Haven't been able to get a copy of the exam yet but as soon as we do people will be able to have suggested solutions!
Post by: jack.gould123 on November 02, 2018, 02:27:44 pm
Post by: benmcleod on November 02, 2018, 02:28:27 pm
Post by: LOL_ABC on November 02, 2018, 02:30:11 pm
Post by: Anne Boleyn on November 02, 2018, 02:50:54 pm
Guys rip i thought the dependent variable was measuring from the stopwatch and not the rate of photosynthesis itself rippppWHATT!! I said rate of carbon dioxide absorption 😩
Post by: vox nihili on November 02, 2018, 02:59:02 pm
Post by: Elsa//768 on November 02, 2018, 03:09:32 pm
Post by: Bri MT on November 02, 2018, 03:37:25 pm
I was initially quite confident going into the exam since my SAC marks have been quite good for the whole year and I've done many practice exams... But now I am just so disappointed in myself :'( :'(:'(
I'm sorry to hear that you feel that way. Your exam score may not be what you fear, but hopefully even if it is, your study score can be pulled up by the good work you've been doing for the rest of the year. It's really difficult to be kind to yourself when you feel like that, but I promise that the work you've been doing and all the effort isn't meaningless no matter what exam score you get. You now have better understanding of yourself, not only in a biological sense, but in how you can push past stress and frustration to keep doing good work, as well as learning more about where your interests lie. All the self dicipline and time management you've been practicing may seem shallow now, but these skills are incredibly valuable in all aspects of life - so even if you don't get the score you want out of your bio journey you're still getting important value.
You're allowed to feel however you're feeling now, but know that this will pass and the strength and understanding you've practiced will stay.
Best of luck
Post by: Hiea on November 02, 2018, 03:55:25 pm
On that note, I really can't gauge how well I did. I'm just kind of . . . acknowledging the fact that it's over? Is that just me? :-\
Post by: Tadd12345 on November 02, 2018, 04:02:37 pm
- increased presence of memory T cells
- increased presence of memory B cells
- increased presence of molecules able to neutralize toxin
I literally made stuff up and tried to get down 3 dot points
Also for last question I said presence of random errors (due to small sample size) may have affected results and maybe a confounding variable. I spoke in very general terms and I’m sure I got it wrong
On the other hand multiple choice was pretty easy!
Mod edit: pls don't double post
Post by: vox nihili on November 02, 2018, 04:11:49 pm
For the Botox question I said Botox injections would have increasingly weaker results due to
- increased presence of memory T cells
- increased presence of memory B cells
- increased presence of molecules able to neutralize toxin
I literally made stuff up and tried to get down 3 dot points
Also for last question I said presence of random errors (due to small sample size) may have affected results and maybe a confounding variable. I spoke in very general terms and I’m sure I got it wrong
On the other hand multiple choice was pretty easy!
Mod edit: pls don't double post
You should pick up 1 or 2 marks for that! Good on you for bullshitting well :D
Post by: Owlbird83 on November 02, 2018, 04:41:27 pm
I wasn't really sure about the botox question, I described both cell mediated and humeral immunity. I just wrote down a lot of stuff hoping some would be what they were looking for.
I was't too sure about the transitional fossil one, I said fins for swimming and lungs for breathing, and described what transistional fossils were. Hopefully I got one or two marks out of that.
The multiple choice was quite easy.
I was relieved that the experimental design stuff wasn't too bad, it was better than last year's.
Post by: Snickitty on November 02, 2018, 04:41:38 pm
Also what did everyone put down for the 3 organelles involved in transport of protein around the cell? I could only think of endoplasmic recticulum and golgi body. I suppose nucleolus might have been acceptable??
Post by: Owlbird83 on November 02, 2018, 04:45:17 pm
Also what did everyone put down for the 3 organelles involved in transport of protein around the cell? I could only think of endoplasmic recticulum and golgi body. I suppose nucleolus might have been acceptable??
I did rough ER and golgi and I wasn't too sure about the last one, I did mitochondria for providing ATP. But it did say 'directly involved' and I don't know if its direct. Some of my friends did plasma membrane and vesicles for the third one.
Post by: Agimo on November 02, 2018, 04:52:15 pm
Post by: Tadd12345 on November 02, 2018, 04:54:04 pm
- “Chemicals such as resin”
- “pheromones to attract predators to engulf pathogens”
What did everyone else write? @snickitty I’d right neither the textbook nor the ATARNOTES book mention anything more than “chemicals and toxins (I.e. resin)”
Post by: PhoenixxFire on November 02, 2018, 05:02:52 pm
I’ll be getting a copy of the exam tomorrow so we’ll have solutions up by tomorrow night sometime at the latest ;D
Post by: briv01 on November 02, 2018, 05:05:51 pm
Also, the organelles for export I wrote were Rough ER, Golgi apparatus and secretory vesicles
Post by: Yacoubb on November 02, 2018, 05:46:11 pm
Yikes, the ATAR notes book really let me down on that plant defence question, all it says is that chemicals can be used kill pathogenic organisms but not any specific examples. :'(
Also what did everyone put down for the 3 organelles involved in transport of protein around the cell? I could only think of endoplasmic recticulum and golgi body. I suppose nucleolus might have been acceptable??
I did rough ER and golgi and I wasn't too sure about the last one, I did mitochondria for providing ATP. But it did say 'directly involved' and I don't know if its direct. Some of my friends did plasma membrane and vesicles for the third one.
Not too sure because I don't have the question but mitochondria may be accepted. It has been alluded to in past questions (VCAA 2012 exam 2) as a component of protein synthesis. Nucleus would also have been an answer.
Post by: Anne Boleyn on November 02, 2018, 05:50:49 pm
I wrote a mutation occurred in the regulatory gene that controls the production of a death ligand, resulting in the overproduction of this molecule. I’m not sure if that’s correct though???
Post by: darkz on November 02, 2018, 06:04:06 pm
Hey guys for the “describe at a molecular level how excess apoptosis occurs(or something like that)” question
I wrote a mutation occurred in the regulatory gene that controls the production of a death ligand, resulting in the overproduction of this molecule. I’m not sure if that’s correct though???
I hope that is, cause that's what I wrote haha
Post by: Thurmanator on November 02, 2018, 06:09:21 pm
Hey guys for the “describe at a molecular level how excess apoptosis occurs(or something like that)” question
I wrote a mutation occurred in the regulatory gene that controls the production of a death ligand, resulting in the overproduction of this molecule. I’m not sure if that’s correct though???
There's probably going to be multiple accepted answers for that question given that it said "suggest". I wrote about an excess production of signalling molecules that induce apoptosis in a nearby cell, probably won't get me full marks, but hey, I can't do anything about it now.
Also for everyone asking about the very last question with the other possible explanations about the results I would bet my life that it's:
- One type of algae may have had a faster rate of cellular respiration
- The pigment in the red algae may have diffused into the solution
Post by: jinaede1342 on November 02, 2018, 08:45:05 pm
Post by: darkz on November 02, 2018, 08:47:36 pm
Hi, I'm just wanting to ask about the first question in section B. I think I've misread the question, was the question asking us to describe transcription or translation? :/ Also what did people get for the phylogenetic tree question about convergent evolution? Thanks in advance!
Translation. I just picked two similar ones e.g. the shark and dolphin cause they were similar length, cartilaginous, not common recent ancestor and similar diet
Post by: jinaede1342 on November 02, 2018, 08:49:15 pm
Post by: hannahsayce on November 02, 2018, 09:04:07 pm
Hi, I'm just wanting to ask about the first question in section B. I think I've misread the question, was the question asking us to describe transcription or translation? :/ Also what did people get for the phylogenetic tree question about convergent evolution? Thanks in advance!
I did the humpback whale and the shark whale because they both developed structures for filtering krill however were on the two different phylogenetic trees thus not resulting from a common ancestor... is that right?
Post by: darkz on November 02, 2018, 09:07:36 pm
I did the humpback whale and the shark whale because they both developed structures for filtering krill however were on the two different phylogenetic trees thus not resulting from a common ancestor... is that right?
Yeh, that should be fine. (Sharks are fish, while dolphins are mammals. So I suppose anyone who did Shark + Dolphin + plausible reason should get the 2 marks for convergent evolution). Conversely, for divergent, should be two fish or two mammals I'd say.
Post by: Hirul1280 on November 02, 2018, 10:30:13 pm
I wrote down phytoalexins and defensins for the plant chemicals
Also, the organelles for export I wrote were Rough ER, Golgi apparatus and secretory vesicles
Not sure if secretory vesicles are organelles but Mitochondria perhaps (since exocytosis is Active transport)?
Post by: Hirul1280 on November 02, 2018, 10:34:11 pm
Hey guys for the “describe at a molecular level how excess apoptosis occurs(or something like that)” question
I wrote a mutation occurred in the regulatory gene that controls the production of a death ligand, resulting in the overproduction of this molecule. I’m not sure if that’s correct though???
I thought the premise of this question was an 'Auto-immune' disorder (self-intolerant), Cytotoxic T cells would release cytokines (then outlined the extrinsic pathway)
Post by: darkz on November 02, 2018, 10:47:52 pm
Not sure if secretory vesicles are organelles but Mitochondria perhaps (since exocytosis is Active transport)?
Secretory vesicles would count
I thought the premise of this question was an 'Auto-immune' disorder (self-intolerant), Cytotoxic C cells would release cytokines (then outlined the extrinsic pathway)
Both seem like valid answers
Post by: MAGGOT on November 03, 2018, 07:17:22 am
I wrote down phytoalexins and defensins for the plant chemicalsInstead of vesicles I said cell membrane 🤷♀️
Also, the organelles for export I wrote were Rough ER, Golgi apparatus and secretory vesicles
Post by: jainamhs_ on November 03, 2018, 07:56:35 am
I’m a new user to AtarNotes, but I just wanted to ask a couple questions about the exam which I’m still unsure / anxious about...
1) For the organelles involved in exocytosis, could you have also written ribosome (some people are saying it is meant to be explicitly involved in transport of the polypeptide)
2) When it asked how uncontrolled apoptosis is possible, is it alright to say an error in T-helper cells that caused them to detect identical antigens on similar cells of a tissue as non-self (then NK and Tc cells come into play)
3) In the social implications for the vitamin A rice, would it be alright to mention that consumers may be wary of genetically modified foods (kind of a stigma) even though it wasn’t mentioned? And also, would a social implication for Bt corn be that people of lower socioeconomic status are forced to handpick crop and sustain rashes for a living?
4) What would’ve been appropriate responses for the very final short answer question - why is keeping the tubes in the dark a control, and what are two possible explanations?
Thanks in advance!
Post by: sarahzz on November 03, 2018, 09:42:19 am
1.What did you guys write for the question asking about structural features of the transitional fossil?
2.What were chemical barriers for a plant? I wrote shedding of infected leaves etc. and the plant producing toxins, but not sure if this is right..
Post by: gab.r_se on November 03, 2018, 09:47:53 am
Hey guys!
1.What did you guys write for the question asking about structural features of the transitional fossil?
2.What were chemical barriers for a plant? I wrote shedding of infected leaves etc. and the plant producing toxins, but not sure if this is right..
I said that for 2. as well. For the structural features, I said even toed hooves and fins.
Post by: vox nihili on November 03, 2018, 10:17:07 am
We should hopefully have some solutions up for you today!
Post by: RazzMeTazz on November 03, 2018, 10:57:56 am
Post by: vox nihili on November 03, 2018, 11:03:32 am
Is a copy of the exam available yet? :)
We won't be making a copy available here because VCAA exams are copyrighted.
Post by: LOL_ABC on November 03, 2018, 01:31:13 pm
Ohh okay, do you know where I could find one? :) Thanks
Yes next year on the VCAA website :)
Post by: EllingtonFeint on November 03, 2018, 03:51:50 pm
Post by: vox nihili on November 03, 2018, 05:07:25 pm
OHMIGOSH I’m so scared of looking at this page. I keep reloading the tab and then shutting before reading anything. I’m so afraid 😱
Still no exam in our hands unfortunately
Post by: AnonymooseUser on November 03, 2018, 05:14:10 pm
Post by: PhoenixxFire on November 03, 2018, 05:17:01 pm
Just curious about what people think the A+ cutoff will be for the 2018 exam? Similar to 79% in 2017 (correct me if this is wrong) or closer to mid 80s?I reckon it’ll be higher than last year given last year was a bit of a surprise. I don’t think it’ll be quite 85% though. Maybe 82-84% or something (but I haven’t actually seen the exam yet, from what I’ve heard though it seems there were only a few questions that everyone struggled with).
Post by: Lear on November 03, 2018, 05:19:40 pm
We won't be making a copy available here because VCAA exams are copyrighted.
Has VCAA asked AN not to post exams or was this a decision made solely by AN to not post exams this year?
Post by: O2square on November 03, 2018, 05:20:10 pm
Just curious about what people think the A+ cutoff will be for the 2018 exam? Similar to 79% in 2017 (correct me if this is wrong) or closer to mid 80s?
I found the exam tougher than last years and I've been hearing a lot of others have found it hard as well, I'm not too sure, but considering that quite a few people did find it difficult, I'd say the cutoff might be lower this year.
But then again it is hard to predict!
Post by: gab.r_se on November 03, 2018, 05:25:10 pm
I found the exam tougher than last years and I've been hearing a lot of others have found it hard as well, I'm not too sure, but considering that quite a few people did find it difficult, I'd say the cutoff might be lower this year.
But then again it is hard to predict!
The short answer was a bit tougher than last years, but the multiple choice was quite easy, so maybe the cutoff will be a tiny bit higher than the 2017 exam.
Post by: jinaede1342 on November 03, 2018, 05:38:15 pm
The short answer was a bit tougher than last years, but the multiple choice was quite easy, so maybe the cutoff will be a tiny bit higher than the 2017 exam.
The multiple choice questions didn't feel too hard but there were definitely a few questions where I was tossing up between two answers/a little hesitant in completing, like the evolutionary timeline where we had to label P,Q,R, the gel electrophoresis diagnosis and the precision and accuracy graphs, where I didn't feel as confident in my answers.
Post by: O2square on November 03, 2018, 06:28:54 pm
The multiple choice questions didn't feel too hard but there were definitely a few questions where I was tossing up between two answers/a little hesitant in completing, like the evolutionary timeline where we had to label P,Q,R, the gel electrophoresis diagnosis and the precision and accuracy graphs, where I didn't feel as confident in my answers.
Yeah I agree, I didn't feel too confident with my answers for a few of the multiple choice questions either. I felt as if some of them weren't as clear.
Also was very confused with the precision and accuracy questions
rip 2(?) marks I thought the short answer was definitely harder than last years for sure though.
Post by: moonlight2018 on November 03, 2018, 06:52:40 pm
Question 1
a. Ribosomes attach to the mRNA in the cytoplasm of the cell (1m); an initiator codon on mRNA binds to first anticodon of tRNA (1m); the codon on the mRNA and anticodon on the tRNA that match one another will result in the release of an amino acid to join the growing polypeptide chain(1m).
b. Rough endoplasmic reticulum- packaged into transport vesicle (1m); golgi body- polypeptide is folded and modified into functional protein (1m); secretory vesicle- release protein into extracellular fluid by exocytosis (1m).
Question 2
a. Cell shrinks and loses contact with neighbouring cells, leading to the condensation of chromatin and its' degradation (1m); nuclear membrane degrades while the chromatin clumps into chromatin bodies (1m); the cell breaks into apoptotic bodies containing densely packed organelles (1m). - Blebbing is not an acceptable answer; choose two
b. Regulates cell proliferation (1m); maintaining cellular integrity (1m); plays a central role in the formation of appendages and other bodily structures during embryonic development (1m).- Any two of these answers
c. Loss of proper growth factor (1m); oxidative damage (1m); irreversible DNA damage (1m).- Any two of these answers
Question 3
a. The secretion of anti-bacterial or anti-fungal agents, such as resins and tannins (1m); the release of defensins from germinating seeds to prevent the growth of pathogens (1m); the secretion of gum around infected site to disallow pathogens from entering the site (1m)- Any two of these answers
b. Ciliated membranes (1m); intact skin (1m); mucus secretions (1m).- Any two of these answers
c. Complement proteins destroy bacterial cell wall and attracts macrophages to the site of infection (1m); NK cells are cytotoxic and can destroy cell that have been invaded by viruses by rupturing the membrane of the infected cell.
Question 4
a. Correct diagram (1m); correct explanation (1m)
b. Changing the 3D shape of the polypeptide chains (1m)
c. During the first botox injection, antigen presenting cells present the foreign epitopes to helper T cell through the MHC II complex. The helper T cell then activates the production of plasma B cells (1m); plasma B cells produce antibodies against the antigens of Clostridium botulinum. Some B cells become memory B cells (1m); during the secondary immune response, the immune system develops an immunological memory of that antigen, so it could respond quicker and stronger when presented with the same antigen for the second time (1m)
Question 5
a.
i. 1958 (1m)
ii. A higher number of reported measles lead to a higher number of deaths (1m); both graphs demonstrate a similar trend in the fluctuation of the number of reported measles and the number of deaths between 1954 and 1966, followed by a drastic drop in the number of reported measles and the number of deaths between 1966 and 1967 (1m)
b. Herd immunity occurs when a significant portion of a population is vaccinated, providing some protection for individuals who have not developed immunity (1m); herd immunity makes it difficult for a disease to spread because there are very few susceptible people to the disease (1m).
Question 6
a. A structural gene is responsible for the production of proteins that affect the structure or function of an organism (1m); a regulatory gene is a gene involved in controlling the expression of one or more genes (1m).
b. The expression of Hox genes Unx and Scr can be turned 'on' or 'off' to control the growth of different appendages. (1m)
c. BMP 4 gene codes for the production of a protein that stimulates bone growth, which stimulates beak growth in finches or jaw formation in cichlid fish (1m);
Finches with larger beaks have larger amount of BMP4 gene expression (1m); Finches with high beak depth and width are able to crush large and hard seeds (1m)
OR High level of BMP4 gene expression results in thicker jaws (1m); jaw gets shorter and thicker to enable specialized biting in these cichlid species (1m)
Question 7
a. Natural variation exists because of random mating , random fertilisation, recombination between homologous chromosomes during meiosis (2m- with explanation on how these factors can lead to an increase in natural variation); natural variation is possible because of the presence of different alleles within the population that enable the ability of individuals to survive and reproduce (1m)
b. Founder effect (1m); allele frequency of the new population is a not a representative of the original population because of a small number of individuals in the small island as compared to a larger number in the large island (1m)
c. Shorter hind leg is a favourable phenotype (1m); this phenotype will be passed onto subsequent generation because of the ability of these lizards to survive and to produce fertile offspring (1m)
Question 8
a. Binds to the active site of the enzyme (1m); prevent folic acid from binding to the enzyme (1m)
b. Prevent DNA replication and transcription (1m); prevent protein synthesis in translation (1m); interfere with the synthesis phase of interphase during cell replication (1m)
c. No, antibiotics interfere with bacterial growth by disrupting the key aspects of bacterial metabolism (1m); eukaryotic cells are not affected because of difference in structure and metabolic pathway to bacteria (1m)
Question 9
a. Pakicetus is extinct (1m)
b. Ambulocetus fossil has features of ancestral land mammal and present-day cetaceuans (1m); Ability to walk on land to obtain more energy from a large variation of food on land (1m); Have fins to hunt underwater (1m).
c.
i. Any two of humpback whale, common bottlenose dolphin, burrunan dolphin and killer whale or any two of whale shark, bronze whaler and blacktip reef shark (1m); share a common ancestor but difference in niche leads to difference in average length (1m)
ii. One from phylogenetic tree A and the other from phylogenetic tree B (1m); no common ancestor but similar environmental pressure and similarity in diet leads to similar physical appearance (1m)
d. DNA hybridisation with description (1m); comparison of amino acid sequences with description (1m)
e. Outcome 1: extinction due to very low genetic diversity count and high level of human activity (1m); Outcome 2: become a new species due to a long period of isolate, occurs when these dolphins cannot interbreed with outside population to produce fertile offspring (1m).
Question 10
a. Yes, they are transgenic because they contain foreign genetic materials (1m); Bt cotton contains genes from Bacillus thuringiensis (1), golden rice contains genes from Erwinia uredovora and Narcissus pseudonarcissus (1m)
b. Insect resistance, crop yield will increase due to a reduction in insect damage (1m)
c. Bt cotton (social implication: increased cost of plant Bt cotton; biological implication: can trigger an allergic reaction) (2m); golden rice (social implication: reduction in Vitamin A deficiency within a large population; biological implication: cross pollination between Golden Rice and non-genetically modified crops) (2m)
Question 11
a. If photosynthesis occurs, then phenol red indicator will change from yellow to pink.
b.
1. same number of algae balls in each test tube
2. time given for each experimental set
3. initial amount of dissolved carbon dioxide gas in the solution
4 (choose 3): temperature of algae balls in each test tube
c. IV: Colour of algae balls; DV: change in the colour of pH indicator
d. No change in the colour of pH indicator for each test tube (1m); same colour change of the pH indicator for each test tube (1m)
e. To determine whether phenol red indicator will change colour from yellow to pink without light (1m)
f. (unsure)- my understanding is that it is asking whether there are other factors that can lead to the change in phenol red indicator colour from yellow to pink
1. Some of the dissolved carbon dioxide gas have been lost to the environment, causing the phenol red indicator to change colour (1m)
2. The change of phenol red indicator from yellow to pink in the test tubes without light is caused by the dissolved carbon dioxide gas, and not because photosynthesis is not present (1m)
Post by: jinaede1342 on November 03, 2018, 07:25:43 pm
Could activated caspases be considered correct here
Question 2
a. Cell shrinks and loses contact with neighbouring cells, leading to the condensation of chromatin and its' degradation (1m); nuclear membrane degrades while the chromatin clumps into chromatin bodies (1m); the cell breaks into apoptotic bodies containing densely packed organelles (1m). - Blebbing is not an acceptable answer; choose two
Post by: PhoenixxFire on November 03, 2018, 07:53:33 pm
Hey guys! We've found a copy of the exam so we're going to start uploading suggested answers.
Here's the answers we got for the multiple choice (we were missing one page, which is why some have question marks)
1. B
2. C
3. D
4. B
5. C
6. C
7. D
8. C
9. A
10. A
11. C
12. D
13. B
14. B
15. B
16. B
17. A
18. D
19. C
20. C
21. A
22. C
23. D
24. B
25. A
26. A
27. A
28. D
29. A
30. C
31. B
32. ?
33. ?
34. ?
35. ?
36. ?
37. B
38. C
39. B
40. C
Post by: vox nihili on November 03, 2018, 08:09:32 pm
(http://i65.tinypic.com/sl0ilz.png)
Post by: yeetlebeetle on November 03, 2018, 08:26:36 pm
It has been our practice in previous years to post exam booklets; however, VCAA has asserted their copyright in multiple spaces such as this in the past years. We agree that it is frustrating, but ultimately copyright does secure an organisation's right to have its intellectual property protected.
Post by: vox nihili on November 03, 2018, 08:35:50 pm
This question dealt with apoptosis.
Potentially a number of potential answers here, including: cleavage of caspases, release of cytochrome c from mitochondria, autodigestion of cellular contents.
Apoptosis facilitates the removal of defective cells and allows for the refinement of normal development.
Would accept other answers here. Any reference to the role of apoptosis in clearing infection or cancer is reasonable.
There may be a mutation in a death receptor molecule that makes it constitutively active/more sensitive to death ligands, thereby seeing the threshold for the activation of apoptosis decrease and more apoptosis occur.
As above, there are many potential answers here. The marks will come from providing a reasonable (at a VCE level) mechanism for the increased likelihood of apoptosis and making a statement about the effect of your described mechanism on seeing more cells die.
EDIT: formatting didn't work—we'll post a complete set of answers later, but this is legible from context.
Post by: vox nihili on November 03, 2018, 08:39:03 pm
Post by: yeetlebeetle on November 03, 2018, 09:04:38 pm
Post by: vox nihili on November 03, 2018, 09:28:48 pm
This question dealt with cellular transport processes and the immune system through the prism of Botulinum toxin.
Your diagram should show a plasma membrane with an indentation containing clearly labelled Botox [1] and the sides of the membrane should be labelled correctly [2].
Botox could attach to the active site of the protein and thereby inhibit its function.
Many potential answers for this one. The assessors seem to have expected an answer about the fact that Botox destabilises the quaternary structure of the enzyme, but this is unreasonable for VCE biology. Any bioplausible answer should be acceptable.
The reality is that Botox is an enzyme that cleaves SNARE proteins, which anchor vesicles at the plasma membrane for exocytosis. In this way, Botox prevents the exocytosis of neurotransmitters and therefore blocks nerve transmission. This level of detail is not relevant to VCE.
Botox is a protein and will therefore be recognised as non-self [1]. B-cells will produce antibodies complementary to Botox that block its activity [2]. Each injection of Botox leads to a greater immune response to it, thereby explaining the gradual decline in its potency [3].
The same is also true of many antisera. Don't get bitten by a snake twice!
To be clear, PF is helping with all of these questions too
Post by: vox nihili on November 03, 2018, 09:51:35 pm
Post by: jinaede1342 on November 03, 2018, 10:18:25 pm
Post by: Tadd12345 on November 03, 2018, 10:44:28 pm
Post by: vox nihili on November 03, 2018, 10:49:03 pm
These are the answers as we see them; however, we'd really welcome any discussion here and will stick around to answer any questions you have.
The answers contain:
-MCQ answers (checked off by Sine, too!)
-MCQ explanation
-SAQ answers and explanation
Post by: Elsa//768 on November 03, 2018, 11:15:16 pm
I hope it's gonna be lower than last year's score coz I thought this year's short-answer part was harder... (or maybe it was just me ;-;)
Post by: lacitam on November 03, 2018, 11:21:47 pm
Here's question 1.How is a vesicle an organelle?
(http://i65.tinypic.com/sl0ilz.png)
Post by: Erutepa on November 03, 2018, 11:23:19 pm
And many thanks to PF and Vox as well as sine (but only a little to sine ;D) for their fantastic work tonight.
Post by: Sine on November 03, 2018, 11:30:17 pm
For 7b, would it not have been important to specify the founder's effect?It's definitely okay to name the founder effect directly however that would be more the circumstances those populations were in. The important part of this question is actually explaining why there is low genetic diverstiy.
Post by: Erutepa on November 03, 2018, 11:34:04 pm
It's definitely okay to name the founder effect directly however that would be more the circumstances those populations were in. The important part of this question is actually explaining why there is low genetic diverstiy.Sorry,
What I meant to say was, in addition to the provided response, would it not have been important (in order to satisfy full marks) to name the founders effect. It just seemed like they would have wanted you to mention that term in your answer.
Other than that I completly agree with all the other responses. Thanks guys!
Post by: PhoenixxFire on November 03, 2018, 11:40:44 pm
Sorry,Yeah I actually agree with you, Vox and I wrote slightly different answers for that question, but I'd completely forgotten about it until you brought it up haha. Given the question says reasons instead of reason, I think they wanted you to mention both. Will have to check with Vox in the morning though.
What I meant to say was, in addition to the provided response, would it not have been important (in order to satisfy full marks) to name the founders effect. It just seemed like they would have wanted you to mention that term in your answer.
Other than that I completely agree with all the other responses. Thanks guys!
Post by: peachxmh on November 04, 2018, 09:28:45 am
Post by: gab.r_se on November 04, 2018, 10:05:36 am
What does everyone think this year A+ cutoff score is gonna be :P
I hope it's gonna be lower than last year's score coz I thought this year's short-answer part was harder... (or maybe it was just me ;-;)
I agree. I am not confident in my answers at all. I think the cut off will be around the same as last years.
Post by: vox nihili on November 04, 2018, 10:15:06 am
This was a fairly reasonable exam. As with 2017, there were some tricky questions that have again flagged a shifting emphasis of the course. Compared to the previous course, there were more questions than usual that expected you to take in information provided by VCAA and combine it with your own knowledge to work through an answer. These questions were more challenging than they were on the previous course, often requiring a nuanced understanding of the science.
The emphasis on the interpretation of science was also, once again, prominent. These questions will have been challenging to most students; however, they should not be. All of the interpretation of science questions were actually quite straightforward, but in my limited experience this has been a part of the course that biology teachers have struggled to teach in classrooms and consequently students have struggled in. Understanding these fundamentals of science is critical to doing good science in the future, so if you found these questions difficult please bear this in mind if you continue to study science in the future—understanding how scientific knowledge is generated by experiments is the single most important thing to understand about science!
I can't see any reason why the A+ cut-off would shift in either direction by a large amount, but trying to predict the cutoff is a mug's game.
Were there any questions all of you wanted to discuss?
How is a vesicle an organelle?
An organelle is just a discrete, functional component of a cell. A vesicle has always been accepted by VCAA as an organelle and most text books have presented it as such. Is there any particular reason you think a vesicle shouldn't be classed as an organelle? Happy to be corrected as always!
Sorry,
What I meant to say was, in addition to the provided response, would it not have been important (in order to satisfy full marks) to name the founders effect. It just seemed like they would have wanted you to mention that term in your answer.
Other than that I completly agree with all the other responses. Thanks guys!
Yeah I actually agree with you, Vox and I wrote slightly different answers for that question, but I'd completely forgotten about it until you brought it up haha. Given the question says reasons instead of reason, I think they wanted you to mention both. Will have to check with Vox in the morning though.
This is a good point you raise. The short answer is I'm not sure. In our answer, we've merely described the process by which variation occurs without naming the process. Given that it is a two mark question, they might have either expected founder effect [1] and an explanation of founder effect [2], alternatively (and I'd suggest less likely) they would go with a marking scheme for that question similar to ours.
Hey guys, so this is a bit of a panicked question but I was wondering whether we were allowed to write outside of the border in the exam paper where it doesn't say that you can't write on it (in yellow highlight in the picture I attached below)? I wrote one sentence outside the bottom of the border and a couple words off the side so I'm really hoping you can LOL (should be good knowledge for next year anyway)
You're really not supposed to but I think there might be recourse to look at the margins if they suspect something is written in them. I think the margins are a sort of "can be cut off" kind of think, not necessarily will be.
That said, this info is based on my year, which was the first year to use the margins—so they might have been a bit nicer back then.
Post by: juliette3901 on November 04, 2018, 01:06:17 pm
Post by: PhoenixxFire on November 04, 2018, 01:22:25 pm
Hi guys was wondering if there was the 2018 exam copy so i can try remember my mc answers!We can’t post a copy because it’s copyrighted.
Post by: Friendsfvv on November 06, 2018, 11:18:05 am
I agree. I am not confident in my answers at all. I think the cut off will be around the same as last years.Same here, I think the A+ cut off wouldn't fluctuate as such. it would probably differ by 1-2% max.
Does anyone have a copy of the exam?? I understand that you can't post it here, but is there another way that I can get a copy of it??
I was thinking of asking my biology teacher for another copy, but I wasn't sure if she would give it to me.. How does ATARNOTES get a copy of the exam? ???
Post by: K888 on November 06, 2018, 11:25:39 am
Same here, I think the A+ cut off wouldn't fluctuate as such. it would probably differ by 1-2% max.I would recommend speaking to your biology teacher.
Does anyone have a copy of the exam?? I understand that you can't post it here, but is there another way that I can get a copy of it??
I was thinking of asking my biology teacher for another copy, but I wasn't sure if she would give it to me.. How does ATARNOTES get a copy of the exam? ???
Post by: PhoenixxFire on November 06, 2018, 11:29:59 am
Does anyone have a copy of the exam?? I understand that you can't post it here, but is there another way that I can get a copy of it??Your teacher should have a copy (or another bio teacher at your school). The exam supervisors normally have spares and most teachers grab a copy after the exam.
I was thinking of asking my biology teacher for another copy, but I wasn't sure if she would give it to me.. How does ATARNOTES get a copy of the exam? ???
Post by: bacteriophage on November 06, 2018, 11:41:35 am
Post by: vox nihili on November 06, 2018, 01:34:20 pm
anyone else say Salicylic acid for physical first line plant defense mechanisms?
You’ll probably know better than I do, but isn’t salicylic acid only produced by one species of plant?
How does it work? If it’s in the leaves and poisons pathogens it can’t be taken as an answer. If however it prevents entry of pathogens it can probably.
Post by: Monkeymafia on November 06, 2018, 06:52:24 pm
Significance of BMP4 gene in terms of galapagos question:
- BMP4 codes for a bone growing protein that stimulates bone growth and thus, affects the size and shape of finch beaks
- the longer BMP4 is expressed, the greater the beak size (bigger beaks allowed for finches to crack open hard seeds)
- this allowed for rapid diversification of finches to fill all available ecological niches (adaptive radiation)
2 chemical plant defences:
- production of abscisic acid to shed infected leaves
- production of toxic chemicals (phytoalexins) to prevent pathogen growth
Post by: vox nihili on November 06, 2018, 07:18:13 pm
Would I recieve marks for the following:
Significance of BMP4 gene in terms of galapagos question:
- BMP4 codes for a bone growing protein that stimulates bone growth and thus, affects the size and shape of finch beaks
- the longer BMP4 is expressed, the greater the beak size (bigger beaks allowed for finches to crack open hard seeds)
- this allowed for rapid diversification of finches to fill all available ecological niches (adaptive radiation)
2 chemical plant defences:
- production of abscisic acid to shed infected leaves
- production of toxic chemicals (phytoalexins) to prevent pathogen growth
Your answer to the BMP4 question sounds great, so that should pick you up the marks yes...although the jump from the effect of BMP4 to how it causes adaptive radiation is a little abrupt.
I don't think you'd get a mark for phytoalexins, although it's borderline. The question asks about things that prevent pathogens from getting in. By the googling I've just done (I know next to nothing about plants), phytoalexins seem to kick in once an infection has already occurred.
Likewise for abscisic acid.
I think it's really a matter of how anal VCAA is about this. That neither of these is really on the VCE course could make it harder to pick up the marks but it's hard to say. The moral of the story here is that it's always safest to stick with the simple things. There are no extra marks for showing off extra knowledge unfortunately!
Post by: PhoenixxFire on November 06, 2018, 07:27:41 pm
The question asks about things that prevent pathogens from getting in. By the googling I've just done (I know next to nothing about plants), phytoalexins seem to kick in once an infection has already occurred.For the part of the question about humans it specifies ways that pathogens are prevented from entering the environment, but for the part about plants it says chemical barriers, which seems to imply prevention of infection but then it says they'd be present in a plant 'that is protecting itself from an invading pathogen' so I don't think they're necessarily required to be barriers that stop infection. Also in the stem of the question it refers to plants developing chemical barriers to stop invading pathogens from causing significant damage rather than just to stop pathogens.
Likewise for abscisic acid.
I think it's really a matter of how anal VCAA is about this. That neither of these is really on the VCE course could make it harder to pick up the marks but it's hard to say. The moral of the story here is that it's always safest to stick with the simple things. There are no extra marks for showing off extra knowledge unfortunately!
Post by: vox nihili on November 06, 2018, 07:37:21 pm
For the part of the question about humans it specifies ways that pathogens are prevented from entering the environment, but for the part about plants it says chemical barriers, which seems to imply prevention of infection but then it says they'd be present in a plant 'that is protecting itself from an invading pathogen' so I don't think they're necessarily required to be barriers that stop infection. Also in the stem of the question it refers to plants developing chemical barriers to stop invading pathogens from causing significant damage rather than just to stop pathogens.
I stand corrected...both of the above would be correct in that case, my apologies!
Post by: dcassss on November 07, 2018, 05:57:16 pm
Post by: Erutepa on November 07, 2018, 07:14:09 pm
could mtdna be used instead of the DNA hybridization answer?As long as you stated that the mtDNA sequences of each species would be compared to determine the degree of relatedness, I would assume this to be satisfactory. Stating mtDNA by itself would not have been enough to get the mark.
Post by: vox nihili on November 07, 2018, 09:23:16 pm
As long as you stated that the mtDNA sequences of each species would be compared to determine the degree of relatedness, I would assume this to be satisfactory. Stating mtDNA by itself would not have been enough to get the mark.
Agreed
Post by: gab.r_se on November 08, 2018, 09:56:39 am
Post by: Erutepa on November 08, 2018, 11:04:31 am
For the question that asks about the techniques to determine relatedness of a species, did it specifically say that we had to provide an example of a DNA method?No. It asked for any two pieces of evidence. Although dna sequence comparison/dna hybridisation would have been an easy one to do.
Post by: gab.r_se on November 08, 2018, 11:07:51 am
No. It asked for any two pieces of evidence. Although dna sequence comparison/dna hybridisation would have been an easy one to do.
Phew. Thanks heaps! Probably should have used those two, though.
Post by: vox nihili on November 08, 2018, 07:29:27 pm
Phew. Thanks heaps! Probably should have used those two, though.
Always best to use what you know and go with the simple stuff, but the stress of exams does funny things to all of us :)
Post by: Erutepa on November 09, 2018, 11:56:08 am
Here are the completed answers that PhoenixxFire and I put together tonight.For the missing MCQ's, I have tried answering them below as I have come across a copy of the exam.
These are the answers as we see them; however, we'd really welcome any discussion here and will stick around to answer any questions you have.
The answers contain:
-MCQ answers (checked off by Sine, too!)
-MCQ explanation
-SAQ answers and explanation
32. D
Explanation: This question dealt with modes of transmission. If a disease is primarily spread by airborne droplets, washing hands or clean needle programs will not prevent disease transmission. Isolation of infected individuals will. Also, vaccination of infected individuals will not prevent transmissions, in order for a vaccination to be effective in conferring immunity, it must be given before exposure to pathogen to allow stimulation of adaptive immune system and production of memory b and t lymphocytes.
33. B
Explanation: This question dealt with comprehension of the supplied table. If two diseases will both be transmitted to the same amount of people from each infected individual, then both diseases would have similar infection rates. By correctly reading other data on the graph, the other statements can be ruled out.
34. D
Explanation: This question dealt with comprehension of gel electrophoresis runs. The band contributing to a disease can be determined by identifying the band which is present in all affected individuals, but not in normal individuals. Therefore, any other individuals who possess the same affected band can be assumed to have that disease also.
35. B
Explanation: this question dealt with antibiotic resistance. It should be known that antibiotic-resistant diseases means antibiotics are less effective towards some bacteria. Exposure does not cause resistant mutation, instead, it selects for resistant phenotypes. Antibiotics affect bacteria, not viruses or humans.
36. D
Explanation: This question deals with the action of insect vectors in spreading disease. It should be known that sn insect vector will enable the protozoan parasite to enter the host.
I think these are all right, but please correct me if I am wrong or if my explanations are confusing/poorly written (I am in a bit of a rush)
Post by: jsmith_1 on November 09, 2018, 01:18:10 pm
I was just wondering if the waxy cuticle could be considered a chemical barrier as well as a physical barrier because of the soluble wax component?
Thanks
Post by: vox nihili on November 09, 2018, 01:25:25 pm
G'day Guys,
I was just wondering if the waxy cuticle could be considered a chemical barrier as well as a physical barrier because of the soluble wax component?
Thanks
Maybe. I know that's a really annoying answer, but it potentially could be, but if they wanted to be harsher, potentially not. I'd be tending towards no, because the cuticle itself is not a chemical.
Post by: jainamhs on November 11, 2018, 07:43:02 am
Would a response including Th cells recognising a group of cells with similar antigens as foreign be an acceptable answers? Basically the extrinsic apoptotic pathway with some autoimmunity too - but is that a malfunction in apoptosis?
Thanks!
Post by: vox nihili on November 11, 2018, 10:35:16 am
For the mass apoptosis question, wouldn't an answer of a localised mutation only affect one cell - as in, if a cell accidentally produces way too many caspases, wouldn't it only affect that cell?
Would a response including Th cells recognising a group of cells with similar antigens as foreign be an acceptable answers? Basically the extrinsic apoptotic pathway with some autoimmunity too - but is that a malfunction in apoptosis?
Thanks!
Genetic diseases are also diseases. It could be a mutation in a germ-line cell.
I think your idea of an immune mechanism is not unreasonable, but I think that talking about helper T-cells being central to this probably would lose you the mark. There are a few steps between helper T-cells and apoptosis. If you'd said cytotoxic T-cells you may have got the mark.
Post by: Erutepa on November 11, 2018, 11:13:13 am
For the mass apoptosis question, wouldn't an answer of a localised mutation only affect one cell - as in, if a cell accidentally produces way too many caspases, wouldn't it only affect that cell?I'll add that since the question refers to malfunctions in program cell death specifically, I would feel inclined to stay away from the action of cytotoxic t cells. Excessive apoptosis in these scenarios would be more so considered due to malfunctions in the immune system rather than malfunctions in the process of programed cell death itself. But that's just my opinion, and I can't speak on behalf of vcaa.
Would a response including Th cells recognising a group of cells with similar antigens as foreign be an acceptable answers? Basically the extrinsic apoptotic pathway with some autoimmunity too - but is that a malfunction in apoptosis?
Thanks!
Post by: vox nihili on November 11, 2018, 02:28:47 pm
I'll add that since the question refers to malfunctions in program cell death specifically, I would feel inclined to stay away from the action of cytotoxic t cells. Excessive apoptosis in these scenarios would be more so considered due to malfunctions in the immune system rather than malfunctions in the process of programed cell death itself. But that's just my opinion, and I can't speak on behalf of vcaa.
I'm not sure I agree. If the immune system is involved in cell death, then a malfunction in the immune system that causes a change in cell death is by definition also a malfunction in cell death.
Anyway, neither here nor there. VCAA could argue either way to be honest.
Post by: Erutepa on November 11, 2018, 04:11:37 pm
I'm not sure I agree. If the immune system is involved in cell death, then a malfunction in the immune system that causes a change in cell death is by definition also a malfunction in cell death.I suppose it just depends on whether you consider the source of the signalling to be part of apoptosis/programmed cell death. I will be interested to see what vcaa end up saying.
Anyway, neither here nor there. VCAA could argue either way to be honest.
Post by: jainamhs on November 12, 2018, 07:09:39 am
I'm not sure I agree. If the immune system is involved in cell death, then a malfunction in the immune system that causes a change in cell death is by definition also a malfunction in cell death.
Anyway, neither here nor there. VCAA could argue either way to be honest.
My rationale during the exam was that a malfunction in a specific cell (say, one somatic cell) that lead it to over-produce caspases would only lead to the death of that one cell - in short, I saw no malfunction in the apoptotic mechanisms of a cell that would lead to other cells also dying that seemed reasonable.
Hence, I made the argument that a specific mutant T-helper cell detects many similar cells as foreign and activated cytotoxic T and NK cells to kill this mass cluster of tissue.
Post by: vox nihili on November 12, 2018, 12:07:28 pm
My rationale during the exam was that a malfunction in a specific cell (say, one somatic cell) that lead it to over-produce caspases would only lead to the death of that one cell - in short, I saw no malfunction in the apoptotic mechanisms of a cell that would lead to other cells also dying that seemed reasonable.
Hence, I made the argument that a specific mutant T-helper cell detects many similar cells as foreign and activated cytotoxic T and NK cells to kill this mass cluster of tissue.
Your rationale for the first bit is close but a little flawed, but that's neither here nor there because you didn't talk about that in the question (it would have been the reasoning in your head). The short and sweet is that a cell can still have a flaw that lowers the threashold for apoptosis, which means that the cells can still propagate viable tissues before the apoptosis kicks in.
If you went to that level of detail in your explanation, you might have got the marks for it. It's certainly a bioplausible argument, and indeed a very intelligent one. I'd be disappointed if VCAA didn't award marks for your answer; it's very sensible.
Post by: jainamhs on November 13, 2018, 05:32:49 pm
The short and sweet is that a cell can still have a flaw that lowers the threashold for apoptosis, which means that the cells can still propagate viable tissues before the apoptosis kicks in.
Thanks for the feedback, but could you briefly explain this? I'm still having trouble understanding why the circumstances of one cell could affect another or many others.
Post by: vox nihili on November 13, 2018, 05:36:45 pm
Thanks for the feedback, but could you briefly explain this? I'm still having trouble understanding why the circumstances of one cell could affect another or many others.
If the mutation is germ line, then all cells have it.
Any cell will undergo apoptosis if provoked. Some cells more readily than others (think of a gut cell versus a neuron, the latter being highly resistant to apoptosis). What the mutation in all the cells might do is lower the threshold for apoptosis. Where a cell would need x amount of stress normally to undergo apoptosis, it might only need a lesser amount in the context of the mutation. Therefore you can still propagate entire tissues, but when a low level stressor occurs, rather than the tissues resisting it, they apoptose.
Post by: jainamhs on November 13, 2018, 05:45:15 pm
If the mutation is germ line, then all cells have it.
Any cell will undergo apoptosis if provoked. Some cells more readily than others (think of a gut cell versus a neuron, the latter being highly resistant to apoptosis). What the mutation in all the cells might do is lower the threshold for apoptosis. Where a cell would need x amount of stress normally to undergo apoptosis, it might only need a lesser amount in the context of the mutation. Therefore you can still propagate entire tissues, but when a low level stressor occurs, rather than the tissues resisting it, they apoptose.
Ah I get it...
So basically the original cell experiences a mutation that lowers it's stress threshold, and hence all daughter cells also inherit this.
That makes sense, thanks vox nihili!
Post by: vox nihili on November 13, 2018, 06:01:10 pm
Ah I get it...
So basically the original cell experiences a mutation that lowers it's stress threshold, and hence all daughter cells also inherit this.
That makes sense, thanks vox nihili!
That's right! To be clear this is some fairly complex reasoning that, whilst not necessarily beyond a VCE student, would be fairly impressive. I'm sure there are simpler answers out there too :)
Post by: PopcornTime on November 13, 2018, 06:48:38 pm
- comparative anatomy + explanation
- if the two organisms were brought together and could not produce fertile offspring, then they are separate separate species
Post by: Erutepa on November 13, 2018, 06:51:15 pm
For the question about two pieces of evidence to justify two organisms are different species could you do:I would agree with this response. I think you will get the full marks.
- comparative anatomy + explanation
- if the two organisms were brought together and could not produce fertile offspring, then they are separate separate species
Post by: jainamhs on November 13, 2018, 08:08:32 pm
Post by: Sine on November 13, 2018, 08:11:33 pm
Also, though it seems most correct, why does the introduction of antiviral drugs cause a reduction in death rates despite people living with HIV increasing? Shouldn't the HIV infection proportion decrease too?The antiviral drugs basically helps those with HIV to continue living - it doesn't remove the infection thus it increases the life span of those with HIV and decreases the death rates of HIV.
The treatment of HIV is not a cure so this means people who would've previously died with HIV would now continue living thus increasing the amount of people living with HIV.
Hope this helps :)
Post by: jainamhs on November 13, 2018, 08:20:37 pm
The antiviral drugs basically helps those with HIV to continue living - it doesn't remove the infection thus it increases the life span of those with HIV and decreases the death rates of HIV.
The treatment of HIV is not a cure so this means people who would've previously died with HIV would now continue living thus increasing the amount of people living with HIV.
Hope this helps :)
Awesome that makes sense... cheers!
Post by: jainamhs on November 13, 2018, 09:15:18 pm
Thanks in advance! 😊
Post by: Erutepa on November 13, 2018, 10:47:16 pm
Also, though it seems most correct, why does the introduction of antiviral drugs cause a reduction in death rates despite people living with HIV increasing? Shouldn't the HIV infection proportion decrease too?The thing with HIV is that it is a bit sneaky and hides latent/dormant within T helper cells. In this dormancy, antiviral drugs are ineffective. However, HIV will spontaneously reactivate/break dormancy and will start replicating again and be present in the blood. This replicating virus can then be targeted by the antiviral drugs, lowering the number of replicating virus to negligible numbers. As such, the individual can suppress the HIV infection, but will not completely overcome it as there will always be this latent virus hiding in the T helper cells. This also means that as soon as one stops antiviral medication, the presence of replicating virus will rapidly increase and cause problems.
I think I say something like:
And also, what would have been an appropriate answer to the questions asking why the tubes were kept in the dark (or their purpose)? I wrote something along the lines of a control and to see how reduced absorption of light impacts on pH colour as an explanation to the results in the main experimental groups, but really not sure.
Thanks in advance! 😊
To act as a control where the colour change can be compared to that of the algae in the presence of light in order to determine if the colour change is a result of photosynthesis since in the absence of light no photosynthesis will occur.
Post by: jainamhs on November 14, 2018, 06:05:28 am
Additionally, in the question regarding two future impacts on the segregated whale / shark species, I wrote two separate dot points on reduced population size and possible extinction, though I'm scared they may be too similar. One was based on out-competition for food by humans due to fishing, and the other was low genetic diversity due to already small population size.
Would these be valid?
Once again, thanks for answering all my unending river of questions! 😋
Post by: vox nihili on November 14, 2018, 09:43:31 am
Thanks for the amazing help guys!
Additionally, in the question regarding two future impacts on the segregated whale / shark species, I wrote two separate dot points on reduced population size and possible extinction, though I'm scared they may be too similar. One was based on out-competition for food by humans due to fishing, and the other was low genetic diversity due to already small population size.
Would these be valid?
Once again, thanks for answering all my unending river of questions! 😋
I can't remember the question precisely off the top of my head (and don't have a copy of the exam handy), but these do sound pretty similar. There are occasions though when VCAA will accept answers that are almost identical as different, which is unfortunate.
Post by: Abi21 on November 16, 2018, 08:14:10 pm
I know the exam was ages ago but for the question asking for chemical defences, I said chemical secretions by the plant (cos thats literally all we were taught). I know its a very general and poor answer but is there any chance that would gain a mark?
Also, for the question abt excessive apoptosis, I said an autoimmune disease could causes excessive cell death (and explained autoantibodies). Is that correct or too vague?
Thanks
Post by: vox nihili on November 16, 2018, 08:23:21 pm
Hi guys,
I know the exam was ages ago but for the question asking for chemical defences, I said chemical secretions by the plant (cos thats literally all we were taught). I know its a very general and poor answer but is there any chance that would gain a mark?
Also, for the question abt excessive apoptosis, I said an autoimmune disease could causes excessive cell death (and explained autoantibodies). Is that correct or too vague?
Thanks
Maybe on the chemical secretions. I doubt it, but if they were being really nice they might. It was a pretty tricky question—my least favourite of the exam.
Probably too vague to get full marks. You don't appear to have linked it well to apoptosis.
Post by: Erutepa on November 16, 2018, 08:39:12 pm
Hi guys,The question specifically stated that it wanted you to talk about malfunctions in apoptosis. If you just talked about and described an autoimmune response I do not think this will get the marks, especially since I would consider this a malfunction in the immune system rather than a malfunction in the process of apoptosis.
Also, for the question abt excessive apoptosis, I said an autoimmune disease could cause excessive cell death (and explained autoantibodies). Is that correct or too vague?
Thanks
But that's just my opinion and all we can do is wait for the examiner's report.
Post by: Abi21 on November 16, 2018, 09:14:50 pm
The question specifically stated that it wanted you to talk about malfunctions in apoptosis. If you just talked about and described an autoimmune response I do not think this will get the marks, especially since I would consider this a malfunction in the immune system rather than a malfunction in the process of apoptosis.damn, thanks anyways
But that's just my opinion and all we can do is wait for the examiner's report.