HSC Biology: Answers & Discussion

[Blissfulmelodii]

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

[Mal08]

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.

[lmnop]

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?!

[Blissfulmelodii]

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 😊😊

[kimmie]

so what do you guys think would be the cutoff for a band 6 this year?

[dazatoN]

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

[genrus]

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!