ATAR Notes: Forum

Archived Discussion => Science Exams => HSC Exam Discussion 2016 => Exam Discussions => New South Wales => Biology Exam Discussion => Topic started by: jakesilove on October 20, 2016, 01:18:22 pm

Title: HSC Biology: Answers & Discussion
Post by: jakesilove on October 20, 2016, 01:18:22 pm
(http://i.imgur.com/m4XV2Zf.jpg)
Hey everyone! Hope the exam went well for you all. We've mocked up some solutions, but this is a hella long paper; check what we've written against your understanding, and discuss the answers below! What did you think of the paper? You can find a copy of the paper HERE!

Multiple Choice
(http://i.imgur.com/SNaKIuP.png)
(http://i.imgur.com/P5OpmNY.png)

Note: There has been a lot of discussion surrounding Question 20, with some people going for B, and others going for D. What did you put down? Why? Let us know below!
Note Note: It looks like the consensus is that the answer to Question 20 is D!

Note Note Note: Our resident Med student actually thinks the answer is B! Tricky, tricky...
Aaaaand now our Med student thinks it's C. Fuck


Core Short-Answer Questions: For answers, just CLICK on the spoiler a few millimetres below this sentence!
Spoiler
(http://i.imgur.com/uCOUPzv.png)
(http://i.imgur.com/QCXtztC.png)
(http://i.imgur.com/UepqHVy.png)


What did you think? Chat below!

Title: Re: HSC Biology: Answers & Discussion
Post by: nibblez16 on October 20, 2016, 01:32:08 pm
Hi, I cant see the answers..
Some multiple choice was confusing, but overall, I guess bio was pretty good :)
Title: Re: HSC Biology: Answers & Discussion
Post by: jakesilove on October 20, 2016, 01:33:05 pm
Hi, I cant see the answers..
Some multiple choice was confusing, but overall, I guess bio was pretty good :)

Hey! Click on the 'Spoiler' and the MC solutions will come up! We're working on more answers now, keep an eye out.
Title: Re: HSC Biology: Answers & Discussion
Post by: Viivek on October 20, 2016, 01:34:03 pm
Hey, I'm pretty sure the answer to question 20 is not A. T cells do not produce antibodies.
Title: Re: HSC Biology: Answers & Discussion
Post by: aimbotted on October 20, 2016, 01:34:49 pm
i put B for number 19 because i read its the scientests discovery so im guessing im probably wrong

for 20 i put d because it was the most correct in my opinion
Title: Re: HSC Biology: Answers & Discussion
Post by: jakesilove on October 20, 2016, 01:36:48 pm
Hey, I'm pretty sure the answer to question 20 is not A. T cells do not produce antibodies.

Hey! It definitely could be D; the wording of the question is a bit ambiguous, hey! Definitely discuss answers here; do you agree? Do you disagree? Why or why not? If we get some consensus, I'll update the answers later on :)
Title: Re: HSC Biology: Answers & Discussion
Post by: nibblez16 on October 20, 2016, 01:40:17 pm
Hey! It definitely could be D; the wording of the question is a bit ambiguous, hey! Definitely discuss answers here; do you agree? Do you disagree? Why or why not? If we get some consensus, I'll update the answers later on :)

This blank thing is coming up...
Title: Re: HSC Biology: Answers & Discussion
Post by: jakesilove on October 20, 2016, 01:42:37 pm
This blank thing is coming up...

That's seriously weird! The direct link is HERE and HERE; maybe try take a look at the spoiler using a different web browser?
Title: Re: HSC Biology: Answers & Discussion
Post by: jakesilove on October 20, 2016, 01:48:40 pm
Some more solutions have been uploaded! What did you include in your answers? Anything more to add? Hit 'reply' to join in the conversation?
Title: Re: HSC Biology: Answers & Discussion
Post by: nibblez16 on October 20, 2016, 01:55:20 pm
That's seriously weird! The direct link is HERE and HERE; maybe try take a look at the spoiler using a different web browser?

Got it :)
Title: Re: HSC Biology: Answers & Discussion
Post by: Bparker on October 20, 2016, 02:18:43 pm
i put B for number 19 because i read its the scientests discovery so im guessing im probably wrong

for 20 i put d because it was the most correct in my opinion

Same here - B for 19 and D for 20 !
Title: Re: HSC Biology: Answers & Discussion
Post by: kevin217 on October 20, 2016, 02:22:52 pm
Hey! It definitely could be D; the wording of the question is a bit ambiguous, hey! Definitely discuss answers here; do you agree? Do you disagree? Why or why not? If we get some consensus, I'll update the answers later on :)
I got D for 20 as well. T cells do not produce antibodies. For 19 I put A.
Title: Re: HSC Biology: Answers & Discussion
Post by: jakesilove on October 20, 2016, 02:25:26 pm
I got D for 20 as well. T cells do not produce antibodies. For 19 I put A.

I've put a note in the original post! Definitely some wiggle room there, but looks like the consensus is that the answer is D :)
Title: Re: HSC Biology: Answers & Discussion
Post by: brenden on October 20, 2016, 02:31:49 pm
PLOT TWIST: we just had a UNSW medical student (Band 6 in Bio) because "B-cells don't directly destroy anything, only make antibodies. T cells can directly kill antigens".

Thoughts on this all? Could the consensus be wrong or is our med student mistaken?
Title: Re: HSC Biology: Answers & Discussion
Post by: Daliaradosevic on October 20, 2016, 02:33:15 pm
Yeah i got answer b for both questions 19 and 20!?
Title: Re: HSC Biology: Answers & Discussion
Post by: zoe_rammie on October 20, 2016, 02:37:32 pm
Okay...with question 20... I actually put C.

And my line of thinking was this:
A) T cells don't produce antibodies so NOPE
B) It's the HELPER T cells that activate B cells
and
D) B cells can't directly destroy any antigens...They can only produce antibodies to IMMOBILISE them. (But not destroy)

And with C):
Lymphocytes actually include both B cells and T cells..

So that's why I think C) is actually the correct answer
Title: Re: HSC Biology: Answers & Discussion
Post by: kevin217 on October 20, 2016, 02:38:08 pm
PLOT TWIST: we just had a UNSW medical student (Band 6 in Bio) because "B-cells don't directly destroy anything, only make antibodies. T cells can directly kill antigens".

Thoughts on this all? Could the consensus be wrong or is our med student mistaken?
Plot twist maybe. C is starting to look more correct if it can't be D
Title: Re: HSC Biology: Answers & Discussion
Post by: zoe_rammie on October 20, 2016, 02:39:18 pm
PLOT TWIST: we just had a UNSW medical student (Band 6 in Bio) because "B-cells don't directly destroy anything, only make antibodies. T cells can directly kill antigens".

Thoughts on this all? Could the consensus be wrong or is our med student mistaken?

OMG THANK YOU. I thought I was the only one who thought this!!!
Title: Re: HSC Biology: Answers & Discussion
Post by: jakesilove on October 20, 2016, 02:43:54 pm
Okay...with question 20... I actually put C.

And my line of thinking was this:
A) T cells don't produce antibodies so NOPE
B) It's the HELPER T cells that activate B cells
and
D) B cells can't directly destroy any antigens...They can only produce antibodies to IMMOBILISE them. (But not destroy)

And with C):
Lymphocytes actually include both B cells and T cells..

So that's why I think C) is actually the correct answer

Our Med student has actually changed her answer to C! This was one fucked question...
Title: Re: HSC Biology: Answers & Discussion
Post by: Lottie99 on October 20, 2016, 02:45:41 pm
As it said that Pasteur looked at them under a light microscope is it reasonable to say that since viruses mainly insert themselves into cells and are very small they're not identifiable under a light microscope?
Title: Re: HSC Biology: Answers & Discussion
Post by: zoe_rammie on October 20, 2016, 02:46:16 pm
Our Med student has actually changed her answer to C! This was one fucked question...

OMYGOD MY HEART WAS BEATING SO FAST COZ I WAS SO SCARED I GOT THAT WRONG BUT YAAAAAAAAAAS PHEWWWW
Title: Re: HSC Biology: Answers & Discussion
Post by: catalyst on October 20, 2016, 03:07:40 pm
Thank you guys!! But can someone explain 23 (b)? I thought salt concentration in the blood would decrease.
Title: Re: HSC Biology: Answers & Discussion
Post by: Sarahanastasianorris on October 20, 2016, 03:13:25 pm
overall pretty happy with how the exam turned out! felt like multiple choice was the hardest but it always seems to be!
Title: Re: HSC Biology: Answers & Discussion
Post by: Sanaz on October 20, 2016, 03:39:15 pm
lol I'm so not going to be happy with my result... idk because cytotoxic T cells dont activate B cells... It's the helper T cells that do that. T cells dont produce antibodies, D seems odd but B cells do destroy melanoma cells indirectly
Title: Re: HSC Biology: Answers & Discussion
Post by: youknowwho on October 20, 2016, 03:56:54 pm
I did B for 19 and C for 20  :-[  :-\
Title: Re: HSC Biology: Answers & Discussion
Post by: aaron_solomon on October 20, 2016, 04:00:05 pm
I did B for 19 and D for 20 :/
Title: Re: HSC Biology: Answers & Discussion
Post by: youknowwho on October 20, 2016, 04:01:35 pm
Thank you guys!! But can someone explain 23 (b)? I thought salt concentration in the blood would decrease.

that's what i wrote
Title: Re: HSC Biology: Answers & Discussion
Post by: Blissfulmelodii on October 20, 2016, 04:13:37 pm
23 (b) I wrote that the salt increases. yay! I was so doubtful about that one
Title: Re: HSC Biology: Answers & Discussion
Post by: justdoit on October 20, 2016, 04:13:53 pm
HATE MULTIPLE CHOICE FOR LYF!
Title: Re: HSC Biology: Answers & Discussion
Post by: kaye.chen7 on October 20, 2016, 04:14:26 pm
I chose B for question 20 too.
Title: Re: HSC Biology: Answers & Discussion
Post by: ehatton2016 on October 20, 2016, 04:31:32 pm
I put A for Q19, C for Q20, there is no evidence in the extract to suggest that its D, plus how could an immune response occur against the specific cancer cells if they do not display a specific antigen? Also, question was fucked ahah

Can anyone explain why the answer to Q13 was B and not D, it asked about segregation not assortment??

Thanks guys!!!
Title: Re: HSC Biology: Answers & Discussion
Post by: naomisirmai on October 20, 2016, 04:36:29 pm
Hello, it is I - the med student.
I say 20 is C because of the theory of Clonal Selection.
Plus all the others sound wrong.

It's an extremely confusing question though.
Title: Re: HSC Biology: Answers & Discussion
Post by: Sanaz on October 20, 2016, 04:52:58 pm
Hello, it is I - the med student.
I say 20 is C because of the theory of Clonal Selection.
Plus all the others sound wrong.

It's an extremely confusing question though.

Hey Naomi do we still have a chance of scraping band 6? I know I got 14/20 for multiple choice (cries) which means I only have 4 marks left to mess up in Section 2 and 3 :O
Title: Re: HSC Biology: Answers & Discussion
Post by: ihardie on October 20, 2016, 04:54:04 pm
Pretty sure the answer to question 20 is C because:
A. T cells don't produce antibodies
B. Cytotoxic T cells don't activate B cells, helper T cells do
D. B cells don't destroy antigens, they just produce antibodies which mark antigens for destruction by macrophages

 :) :) :) :) :)
Title: Re: HSC Biology: Answers & Discussion
Post by: Bestintheworld on October 20, 2016, 05:03:40 pm
Hey Naomi do we still have a chance of scraping band 6? I know I got 14/20 for multiple choice (cries) which means I only have 4 marks left to mess up in Section 2 and 3 :O

That's not true, you can afford to lose more marks than that because it undergoes scaling and other stuff. If you get about 85 raw, you can still get a band 6 :)

-
I did D for Q20 but now that I think about it, C sounds more convincing.
Title: Re: HSC Biology: Answers & Discussion
Post by: alanabb on October 20, 2016, 05:27:14 pm
I put a) for 19. It had weird wording, but I thought it couldn't be d) because it should say that the body cannot *usually* mount an immune response against cancer cells. Because technically, according to the extract, the body can, but only after vaccination.

 I did c) for 20, because a) is wrong. I always thought that b cells produced antibodies which immobilise but do not kill the cell, so it couldn't be d). So I said c, which is also kind of relevant to the clonal selection theory.
Not sure though, just thoughts.
Title: Re: HSC Biology: Answers & Discussion
Post by: jnicko989 on October 20, 2016, 05:36:40 pm
I got A for question 20 - Cytotoxic t cells don't activate B cells, c is irrelevant, and B cells never destroy anything - they trap them and take the to lymph nodes/have markers that detect antigen markers but again, don't destroy.
Title: Re: HSC Biology: Answers & Discussion
Post by: alanabb on October 20, 2016, 05:46:03 pm
I got A for question 20 - Cytotoxic t cells don't activate B cells, c is irrelevant, and B cells never destroy anything - they trap them and take the to lymph nodes/have markers that detect antigen markers but again, don't destroy.

Hmmm I wondered about that, but for A) I know that Helper T-Cells release interleukins that activate B cells that produce the relevant antibodies, but I thought there was a difference between acting as a messenger to B cells and actually producing antibodies? The wording of the question is *produce* and  T cells definitely don't produce antibodies. That's why I think it could be c), because the interleukins produced by the helper T Cells activate replication of the relevant T and B cells (lymphocytes) according to the clonal selection theory.
Title: Re: HSC Biology: Answers & Discussion
Post by: Potato101 on October 20, 2016, 05:48:04 pm
Hello, it is I - the med student.
I say 20 is C because of the theory of Clonal Selection.
Plus all the others sound wrong.

It's an extremely confusing question though.

I put c) :D
Title: Re: HSC Biology: Answers & Discussion
Post by: Zaenab Almayahi on October 20, 2016, 05:49:22 pm
Any suggested answers for the option section? (communication)
Title: Re: HSC Biology: Answers & Discussion
Post by: kevin217 on October 20, 2016, 05:51:36 pm
Did the graph need to be in pen because I drew in pencil?
Title: Re: HSC Biology: Answers & Discussion
Post by: :3 on October 20, 2016, 06:01:30 pm
For question 19, it's asking for what can be inferred from scientist's discovery.
- Since it says "antigen extracted from patient's melanoma cells...injected...stimulates a response", it can be 'inferred' (deduced) that the body does 'mount an immune response against cancer cells' and hence, cannot be D.
- It couldn't be C as it is a reaction to an antigen.
- According to the definition of 'self-antigens' (any molecule or chemical group of an organism which acts as an antigen in inducing antibody formation in another organism but to which the healthy immune system of the parent organism is tolerant), it is made evident that it cannot be B as the other person's body does react to it.
- Therefore leaving A.

For 20, its possible they may double up on the answer (seen it done previously in past exams).
- C is valid as it does cause lymphocytes (i.e. cytotoxic T cells + B Cells) to duplicate.
- D can also be valid as it does not explicitly state how the B cell destroys the melanoma cell.
_______________________________________________________________________________________________________
Kevin 217, it says you're allowed to use pencil to draw diagrams (i.e. graphs), so it should be ok :3
Title: Re: HSC Biology: Answers & Discussion
Post by: stephanieazzopardi on October 20, 2016, 06:01:57 pm
Hello, it is I - the med student.
I say 20 is C because of the theory of Clonal Selection.
Plus all the others sound wrong.

It's an extremely confusing question though.

I agree with Naomi, the answer must be C because T cells don't produce antibodies (A), cytotoxic T cells don't activate B cells, helper T cells do (B), and D cannot be right because B cells don't directly destroy the antigen (the melanoma cells), they differentiate into plasma cells which then release antibodies to fight the antigen.
Btw, I aint no Med student but I study Speech Path and we learn this stuff for fun coz why not.
 :) :) :)
Title: Re: HSC Biology: Answers & Discussion
Post by: RuiAce on October 20, 2016, 06:04:13 pm
Did the graph need to be in pen because I drew in pencil?
Graphs in science are supposed to be drawn with pencil
Title: Re: HSC Biology: Answers & Discussion
Post by: kevin217 on October 20, 2016, 06:05:00 pm
_______________________________________________________________________________________________________
Kevin 217, it says you're allowed to use pencil to draw diagrams (i.e. graphs), so it should be ok :3
Ok good thanks
Title: Re: HSC Biology: Answers & Discussion
Post by: kevin217 on October 20, 2016, 06:05:39 pm
Graphs in science are supposed to be drawn with pencil
Just on the subject, everything in maths is supposed to be in pen right?
Title: Re: HSC Biology: Answers & Discussion
Post by: stephanieazzopardi on October 20, 2016, 06:10:16 pm
Just on the subject, everything in maths is supposed to be in pen right?

Yep. BOSTES specifies 'Black' pen.  8)
Title: Re: HSC Biology: Answers & Discussion
Post by: samsam0001 on October 20, 2016, 06:23:30 pm
With question 26) how was the graph meant to look like? Because i found it troubling since there was no axis for the species so I had to make one myself. Also i think i stuffed it up so I couldn't infer a relationship from this graph. Such a bad exam. :(
Title: Re: HSC Biology: Answers & Discussion
Post by: naomisirmai on October 20, 2016, 07:05:26 pm
Hey Naomi do we still have a chance of scraping band 6? I know I got 14/20 for multiple choice (cries) which means I only have 4 marks left to mess up in Section 2 and 3 :O

What I think is:
- don't panic and try to guess your marks. You never know.
- take into account scaling. This years MCQs were tricky and most people will be in your position.
- wait and see! No more use panicking.

Good luck for the rest of your exams xxx
Title: Re: HSC Biology: Answers & Discussion
Post by: mtse on October 20, 2016, 07:55:01 pm
Haven't done HSC (so I might be wrong sorry) but from my somewhat mediocre VCE/med bio knowledge
Question 20 Answer - I'd put a C
The question is asking for the effect of a "vaccine" - vaccines are a form of artificial active immunity, i.e. it wants to stimulate the body to create its own memory B and T cells (a.k.a lymphocytes) for future use.

The other answers are wrong because:
A - T cells don't produce antibodies
B - Helper T cells activate B cells
D - technically B cells don't destroy anything - they PRODUCE antibodies which may destroy melanoma cells (but from my knowledge cytotoxic T cells are the ones that can destroy cancer cells, pretty sure antibodies are relatively ineffective because cancer cells mutate way too often for an antibody to remain specific to the cell)
Title: Re: HSC Biology: Answers & Discussion
Post by: jack.wheatstone on October 20, 2016, 08:08:16 pm
Hey! I'm not claiming to be an expert or anything, but couldn't the answer to question 19 have to be B?
Technically, since it is suggesting that they use the patients "own" melanoma cells in order to create the vaccine, wouldn't it be impossible for self-antigens to be present on the cancer cells and for them to still be able to fight the melanoma?

Additionally, for question 20... The question kind of could be either C or D couldn't it? Though a Vaccine generally isn't known to specifically be designed to produce lymphocytes via cellular division, technically that is what it does? Additionally, for D whilst antibodies do not directly destroy antigens, technically the production of Plasma B-Cells do produce Antibodies that are responsible for the process of killing the antigens, right? So I think the question could go both ways...
Title: Re: HSC Biology: Answers & Discussion
Post by: jakesilove on October 20, 2016, 08:11:06 pm
Hey! I'm not claiming to be an expert or anything, but couldn't the answer to question 19 have to be B?
Technically, since it is suggesting that they use the patients "own" melanoma cells in order to create the vaccine, wouldn't it be impossible for self-antigens to be present on the cancer cells and for them to still be able to fight the melanoma?

Additionally, for question 20... The question kind of could be either C or D couldn't it? Though a Vaccine generally isn't known to specifically be designed to produce lymphocytes via cellular division, technically that is what it does? Additionally, for D whilst antibodies do not directly destroy antigens, technically the production of Plasma B-Cells do produce Antibodies that are responsible for the process of killing the antigens, right? So I think the question could go both ways...

Hey Jack! Check out all the discussion above; it's pretty clear that Q19/20 are contentious as fuck. Basically, there are good arguments for heaps of possible answers, so no point stressing now! 
Title: Re: HSC Biology: Answers & Discussion
Post by: stephanieazzopardi on October 20, 2016, 08:13:28 pm
Hey! I'm not claiming to be an expert or anything, but couldn't the answer to question 19 have to be B?
Technically, since it is suggesting that they use the patients "own" melanoma cells in order to create the vaccine, wouldn't it be impossible for self-antigens to be present on the cancer cells and for them to still be able to fight the melanoma?

Additionally, for question 20... The question kind of could be either C or D couldn't it? Though a Vaccine generally isn't known to specifically be designed to produce lymphocytes via cellular division, technically that is what it does? Additionally, for D whilst antibodies do not directly destroy antigens, technically the production of Plasma B-Cells do produce Antibodies that are responsible for the process of killing the antigens, right? So I think the question could go both ways...

Yes but this could be BOSTES way of trying to trick you... B cells don't directly destroy antigens, antibodies do.
Title: Re: HSC Biology: Answers & Discussion
Post by: Phillorsm on October 20, 2016, 08:51:54 pm
For question 27b, I said that the mutation affects the lignin in the spiral thickenings, so it would also affect the lignin in the leaves that gives them rigidity. Was I completely off by saying this?
... Is there even lignin in the leaves to give them rigidity??
Title: Re: HSC Biology: Answers & Discussion
Post by: jakesilove on October 20, 2016, 08:57:47 pm
For question 27b, I said that the mutation affects the lignin in the spiral thickenings, so it would also affect the lignin in the leaves that gives them rigidity. Was I completely off by saying this?
... Is there even lignin in the leaves to give them rigidity??

Google has confirmed that there is in fact lignin in some leaves (namely, grass)
Title: Re: HSC Biology: Answers & Discussion
Post by: youknowwho on October 20, 2016, 09:09:22 pm
can someone please explain what on earth is ringbarking ?
Title: Re: HSC Biology: Answers & Discussion
Post by: jakesilove on October 20, 2016, 09:12:31 pm
can someone please explain what on earth is ringbarking ?

It's when you cut around a tree in a circle, essentially destroying the outer layer! This destroys the phloem, which is integral in the transportation of nutrients and sugars to the roots. Thus, the tree will die! (Is a sad face more appropriate?)
Title: Re: HSC Biology: Answers & Discussion
Post by: youknowwho on October 20, 2016, 09:16:58 pm
It's when you cut around a tree in a circle, essentially destroying the outer layer! This destroys the phloem, which is integral in the transportation of nutrients and sugars to the roots. Thus, the tree will die! (Is a sad face more appropriate?)

i chose B (decrease in water transport)  :'( 
Title: Re: HSC Biology: Answers & Discussion
Post by: ehatton2016 on October 20, 2016, 09:51:16 pm
hey guys! Can anyone please explain why Q13 is B and not D????
Title: Re: HSC Biology: Answers & Discussion
Post by: Mal08 on October 21, 2016, 07:23:34 am
Hey guys

Funnily enough, I'm having the opposite anxiety, were it seems I aced multiple choice but my short responses were weaker and I have some questions.

1) For the graph, I was an idiot and did the scale from 0-100. The curve is still visible, with all points properly plotted but will I lose a mark since the scale is too large?

2) For the xylem mutation question, I had two main points. For the first point I briefly went over how xylem vessels are composed of rigid lignin walls and that this mutation would effectively decrease the amount of lignin, decreasing rigidity and having a wilting effect.

 For my second point however, I said something that I haven't even heard anyone else talk about yet. I said that thinning the cell walls of the xylem will effectively thin the walls of the xylem vessel causing it to have a larger diameter. Water moves in the xylem via the TRACT model, in which water passively moves up the vessel by adhering to the cell walls of the vessel alongside the positive pressure that is created in the roots and the negative pressure created in the leaves due to transpiration. By increasing the diameter of the vessel however the SA:V of water contact to xylem walls has decreased and the pressure that is created in the xylem is lessened. This leads to water moving more slowly up the vessel and hence cells that require water for photosynthesis etc receive it more slowly. Overtime this decrease in metabolic rate can potentially lead to wilting as the plant dies

Did i screw myself?

edit: The answer about water leaving the xylem via osmosis at unintentional locations doesn't make too much sense to me which is partly why I avoided it. I've pretty much accepted it as the correct answer as everyone else seems to have put it down but wouldn't eventual osmotic equilibrium alongside the areas where it is unintentially left mean that water will end up still travelling up the plant to the areas it is meant to? I guess the point is that its less efficient water travel?
Title: Re: HSC Biology: Answers & Discussion
Post by: Blissfulmelodii on October 21, 2016, 10:05:05 am
Hey guys

Funnily enough, I'm having the opposite anxiety, were it seems I aced multiple choice but my short responses were weaker and I have some questions.

1) For the graph, I was an idiot and did the scale from 0-100. The curve is still visible, with all points properly plotted but will I lose a mark since the scale is too large?

2) For the xylem mutation question, I had two main points. For the first point I briefly went over how xylem vessels are composed of rigid lignin walls and that this mutation would effectively decrease the amount of lignin, decreasing rigidity and having a wilting effect.

 For my second point however, I said something that I haven't even heard anyone else talk about yet. I said that thinning the cell walls of the xylem will effectively thin the walls of the xylem vessel causing it to have a larger diameter. Water moves in the xylem via the TRACT model, in which water passively moves up the vessel by adhering to the cell walls of the vessel alongside the positive pressure that is created in the roots and the negative pressure created in the leaves due to transpiration. By increasing the diameter of the vessel however the SA:V of water contact to xylem walls has decreased and the pressure that is created in the xylem is lessened. This leads to water moving more slowly up the vessel and hence cells that require water for photosynthesis etc receive it more slowly. Overtime this decrease in metabolic rate can potentially lead to wilting as the plant dies

Did i screw myself?

edit: The answer about water leaving the xylem via osmosis at unintentional locations doesn't make too much sense to me which is partly why I avoided it. I've pretty much accepted it as the correct answer as everyone else seems to have put it down but wouldn't eventual osmotic equilibrium alongside the areas where it is unintentially left mean that water will end up still travelling up the plant to the areas it is meant to? I guess the point is that its less efficient water travel?

Firstly as long as your scale is even then I'm sure they won't take marks off for it. But wasn't the question to draw a line of best fit not a curve of best fit? Or did I stuff that up??

Secondly I wrote the exact same reasoning about the surface area volume slowing the water flow in that xylem question so your not alone. I hope its right
Title: Re: HSC Biology: Answers & Discussion
Post by: Mal08 on October 21, 2016, 11:17:52 am
Firstly as long as your scale is even then I'm sure they won't take marks off for it. But wasn't the question to draw a line of best fit not a curve of best fit? Or did I stuff that up??

Secondly I wrote the exact same reasoning about the surface area volume slowing the water flow in that xylem question so your not alone. I hope its right


Yeah it was line of best fit, didn't mean to confuse you, accidentally wrote that in the post even though I did a line not a curve.

Good to know I'm not alone.
Hopefully that answer gets some marks.
Title: Re: HSC Biology: Answers & Discussion
Post by: lmnop on October 21, 2016, 11:41:32 am
guys i asked this on the other thread as well but just want to know was it ok for me to use short hand in the exam? so i would use a triangle to indicate change and like arrows for increasing and decreasing if that makes sense...like i know you can do that in eco but is it ok for bio or am i screwed?!
Title: Re: HSC Biology: Answers & Discussion
Post by: Blissfulmelodii on October 21, 2016, 05:58:00 pm

Yeah it was line of best fit, didn't mean to confuse you, accidentally wrote that in the post even though I did a line not a curve.

Good to know I'm not alone.
Hopefully that answer gets some marks.

Haha cool. Honestly when I saw curvie it gave me a mini heart attack because I thought I had read it wrong lol

And yeah! Fingers crossed 😊😊
Title: Re: HSC Biology: Answers & Discussion
Post by: kimmie on October 21, 2016, 09:16:55 pm
so what do you guys think would be the cutoff for a band 6 this year?
Title: Re: HSC Biology: Answers & Discussion
Post by: dazatoN on October 22, 2016, 12:51:24 pm
For question 2 multiple choice, the answers is D, pathogens have to survive transmission from one host to another and have to cause disease, the symptoms may be not an illness but rather something else
Title: Re: HSC Biology: Answers & Discussion
Post by: genrus on October 24, 2016, 11:24:52 am
I got D for 20 as well. T cells do not produce antibodies. For 19 I put A.

i put A for 19 as well because the scientists discovered that he had to take cells from the "own" patients cancer to produce the antibody, therefore cancer cells must carry unique antigens as the vaccine wouldn't work for every other person

i got C for 20 though haha! i went via process of elimination with A because B cells produce plasma cells which produce antibodies, not T cells. and then i thought B was wrong because helper Ts stimulate b cells not cytotoxic and D i thought is correct but isn't the only thing that a vaccine will do.

I thought C because b cells and t cells are lymphocytes and when a vaccine enters it triggers a full immune response with all lymphocytes in order to create memory cells for second response. But maybe its wrong because it says "cell division" to produce lymphocytes and im not sure if thats the correct process!