whats the difference between validity, and accuracy
VCE Biology Questions Thread
chemistry1111 validity = are you measuring what you want to measure? and can your results be applied to the general population (important to have random sampling)
accuracy = how close is your data to the 'true,' 'known,' or 'standard' values (comparing your results to what 'should' have happened)
BEST OF LUCK TO EVERYONE FOR TOMORROW!!!
do you guys think we are going to have to draw a phylogenetic tree on the exam?
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md2112 monoclonal antibodies can either stimulate, supress or have no effect on the immune system. it just depends on what the antibody is targeted for.
For cancerous cells, monoclonal antibodies can be modified to carry toxins (anti-cancer drugs), so when the antibody binds to the non-self antigen on the surface of the cancerous cell, it releases the toxins which enter the infected cell and induce apoptosis, causing the cancerous cell to die. This stimulates the immune system.
For autoimmune diseases, antibodies can be targeted to block particular proteins in the pathway of the infection, e.g. with Rheumatoid arthritis, monoclonal antibodies can block a protein that causes inflammation. So blocking that protein will prevent inflammation and help alleviate symptoms of the condition. This suppresses the immune system.
I would suggest having a look at question 6 in the 2022 sample exam as it talks about this.
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chemistry1111 no one can tell what types of questions they will ask. if they do ask it will most likely be drawing 1 or 2 branches on a phylogenetic tree that is already provided, as opposed to drawing an entire tree from scratch. Have a look at question 9c from the 2020 vcaa exam if you want to get an idea of what it might look like.
7 days later
do we need to know about photosystems 1 and 2 in the light dependent stage of photosynthesis? if so could someone please explain.
MCQ 10 in the 2022 vcaa exam involves it but I have never seen any other questions about it ever, nor is it specified in the study design, nor was I taught it by my tutor or at school! just seems like such a random question.
Omg yes! When I did bio last year, I went way to in depth in this. I think Douchy has a video about it somewhere…. And there was stuff on Khan Academy too…
Simply put, there are two photosystems in the membrane of chloroplasts. 1 and 2
Photosystem 2 is the important one
It is able to oxidise oxygen! Which is really hard to do. Using sunlight it splits water into O2 gas and H+ ions, and sends the electron down the transport chain - which pumps hydrogens across the membrane, making a proton gradient…
Etc… etc
bioho4
Hi
This is a bit late to ask that question especially since the bio exam has already passed.
Anyways,
VCAA does not expect you to know the details of the biochemical pathways of photosynthesis (such as photosystems). They only expect you to know the reactants, products and location of each stage of photosynthesis and and role of RuBisCO.
FYI, photosystems 1/2 split H20 in the light dependent stage of photosynthesis.
Hope this makes sense.
bioho4
i think this is the relevant dp from the bio study design:
- inputs, outputs and locations of the light dependent and light independent stages of photosynthesis in C3 plants (details of biochemical pathway mechanisms are not required)
so i'm pretty sure you don't need to know much about photosystems, etc. although confusing, i think vcaa uses diagrams like those to see whether students can link where the inputs and output come into the overall process? and thus determine what stage it is, potentially? was definitely still a kinda random question tho
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Hi bioho4!
Most of diagram was irrelevant, and it included everything you needed to answer the question - given that you knew your standard bio content. The two, and only, pieces of information that was needed was that:
- It was in the light-dependent stage -- this could have been inferred through inclusion of the "sunlight" component [in the diagram].
- The arrows and blank boxes [in the diagram].
Allow me to elaborate;
Given that the biochemical pathway represented was the light-dependent stage of photosynthesis this narrows down all possible inputs to be Water, ADP, and NADP+; and all outputs to be Oxygen, ATP, and NADPH.
Looking at the boxes and arrows, we know that the question asks for the identity of one input (W), and two outputs (V and Z).
To summarise those two points, the answer we are looking for must be a combination of one input and two outputs; that must belong to the light-dependent stage of photosynthesis.
...
Ok, now, with that knowledge lets take a look at all four options;
Option A - 'Water, ATP and NADP+' - We have two inputs and one output here, so that doesn't work.
Option B - 'Oxygen, ATP and NADPH' - We have no inputs and three outputs, this does not work either.
Option C - 'Oxygen, ADP and NADPH' - Ah, one input and two outputs, all of the light-dependent stage of photosynthesis 
.
Option D - 'Carbon Dioxide, ADP and NADP+' - Carbon Dioxide is not apart of the light-dependent stage of photosynthesis, so we need not bother with this option at all.
...
So, in conclusion, Option C was the correct answer, and you didn't need detailed knowledge of the light-dependent stage either.
As the maths shill in me would say, Q.E.D.
...
This was a fairly lengthy post for a MCQ, but I think it was an important post to make.
When you do VCE Biology, you can have faith in that no non-SD content will be assessed - you would (and should) expect that much. And honestly, from personal experience, learning non-SD content is basically useless for many areas of the VCE Biology Study Design; I think doing so would be a regrettable decision, especially in Year 12.
Chances that you get tested on it are extremely slim, and if it is truly non-SD I think consequentials would be awarded anyways. And yes, the extra background knowledge helps, but the tradeoff for time on other subjects is not favourable (this one comes from personal experience 
).
...
My Bio journey is finished for now, but hopefully those still in it (or are yet to begin) will have better luck. Happy studying 
.
3 months later
Is it the RNA polymerase or helicase that unzips DNA for transcription?
Helicase - think of helicopter and its blades cutting through the hydrogen bonds of DNA as an analogy
Hello lovelyherring
RNA Polymerase; it has a built-in Helicase-like component. Whereas DNA Helicase is typically present in DNA replication.
Hope this helps 