VCE Biology Question Thread

[PhoenixxFire]

Hey there doing the NHT VCAA 2017 got a few questions:
For question 4b(ii) [context provided in attachment]:
It asks for two controls for the experiment:
would pH be a control for the experiment? the answers dont state ph as a solution so if not why wouldnt ph be a solution.

You might get away with that answer, it's not great because it says in the stem that they both followed the same method - if they did this correctly then the pH should already be the same.

From question 7c:
[PCR is the context]
What is the function of the DNA primers in the mixture?:
I wrote: DNA primers anneal to specific gene of interest using complementary bases and allow Taq polymerase to bind to the DNA strand.
Would this a good answer?

You're close but you'd lose marks for not using the correct language. DNA primers don't anneal to the gene - they anneal upstream/downstream of it. Rather than saying that they allow taq polymerase to bind to it, it would be more accurate to say that they provide a starting point for taq polymerase to build a complementary strand.

And finally for question 10 c:
Identify two beetle species that would have the least number of differences in their DNA sequences. Explain your answer.
The answer says Species W and X as a "possible answer" Are there other species that can be a possible answer?
Thnx for the help

Man its been a while since I've used BB code

It seems to be the only logical answer. They may have been referring to the explanation given as a possible answer, rather than the species chosen.

[dev_xy]

Hi, just a quick question, if my prerequisite states that I need 30 for biology is it talking about the RAW score of a SCALED score?

[PhoenixxFire]

Hi, just a quick question, if my prerequisite states that I need 30 for biology is it talking about the RAW score of a SCALED score?

It'll be the raw score.

[dev_xy]

It'll be the raw score.

Thank you!

[Livcur16]

Hey guys,
For photosynthesis and cellular respiration, do we only need to know the inputs and outputs of the stages or do we need to know some of the process that goes on within the stages?
Thanks

[Chocolatemilkshake]

Just wondering, in the secondary immune response (second exposure to antigen), do memory B cells need to be stimulated by cytokines (from Helper T cells) in order to proliferate again, or will they automatically proliferate after binding to the specific antigen?

[PhoenixxFire]

Hey guys,
For photosynthesis and cellular respiration, do we only need to know the inputs and outputs of the stages or do we need to know some of the process that goes on within the stages?
Thanks

Just inputs and outputs. You also need to know the "purpose" of photosynthesis and cellular respiration, but that probably just means that you need to know what the ultimate goal of them is (ie making glucose/atp) rather than any specific info. It did used to be in old study designs though so just ignore anything you've seen about it from past exams.

Just wondering, in the secondary immune response (second exposure to antigen), do memory B cells need to be stimulated by cytokines (from Helper T cells) in order to proliferate again, or will they automatically proliferate after binding to the specific antigen?

I don't think so, or at least I don't think they need contact dependent signalling again, although the cytokines circulating probably still help. But don't quote me on that haha.

[sandywu]

Hi I was wondering what is the best way to explain adaptive radiation. And what is the difference between comparative anatomy vs structural morphology?

[pugs]

hi y'all

just a question i wanted to clear up: what is the difference between mtDNA having a fast mutation rate and mtDNA having a lack of recombination? both of these are benefits to using mtDNA, but i keep thinking they contradict each other. would someone be able to explain the difference between the two & why they are beneficial?

thank you!!

[Bri MT]

Hi I was wondering what is the best way to explain adaptive radiation. And what is the difference between comparative anatomy vs structural morphology?

I haven't looked at this compared to VCAA examiners reports but:
In adaptive radiation a range of niches become available (e.g. islands, darwins finches) leading to rapid diversification as populations adapt to those niches/environments.

I'm not 100% sure but pretty confident that anatomy is a subcategory of morphology which is a more general term. I wouldn't use them as 2 seperate examples

hi y'all

just a question i wanted to clear up: what is the difference between mtDNA having a fast mutation rate and mtDNA having a lack of recombination? both of these are benefits to using mtDNA, but i keep thinking they contradict each other. would someone be able to explain the difference between the two & why they are beneficial?

thank you!!

This is a simple explanation but I hope it helps:

Fast mutation rate: there's going to be more base changes to look at (synonymous base changes are particularly useful from a molecular clock perspective but I can't remember if they teach you that in VCE or just tell you to look at region not under selection pressure)
No recombination: you know exactly where the DNA has come from: the mother, and don't need to try and guess what bits are from each parent

[Chocolatemilkshake]

I didn't think NADH was required for anaerobic respiration (isn't it an output?) but in the NHT VCAA 2018 exam, one of the multiple choice questions is...

Question 5
NADH is a coenzyme.
Which one of the following is a correct statement about NADH?
A. NADH is a carrier of electrons and protons between reactions in a cell.
B. NADH is not produced in the glycolysis stage of aerobic respiration.
C. NADH is the immediate source of energy for cellular activity.
D. NADH is required in aerobic respiration but not in anaerobic respiration.

The correct answer is A (which I understand), but was wondering if someone could explain why D is an incorrect statement?

Thanks

[Livcur16]

Hey,
Also just wondering about a question in Insight 2017 exam question 9a)
"Scientists believe that each of the 6 modern species of finch evolved through natural selection from populations of the founder species arriving on each of the islands.
What term do scientists use to describe the emergence of these 6 species from the original founder species?"
I wrote Allopatric speciation, but the solutions say that the only answers that will be accepted is adaptive radiation or divergent evolution,
Why is this?

Also, how does a new strain of virus come into existence?

With transcription factors, is there multiple ways they can work in eukaryotic and prokaryotic cells, like binding to RNA polymerase to enable it to bind/ not bind to the promoter region, or binding to the operator region on the sequence? Do transcription factors function differently in eukaryotic cells and prokaryotic cells?
Thanks so much 

[Geoo]

I didn't think NADH was required for anaerobic respiration (isn't it an output?) but in the NHT VCAA 2018 exam, one of the multiple choice questions is...

Question 5
NADH is a coenzyme.
Which one of the following is a correct statement about NADH?
A. NADH is a carrier of electrons and protons between reactions in a cell.
B. NADH is not produced in the glycolysis stage of aerobic respiration.
C. NADH is the immediate source of energy for cellular activity.
D. NADH is required in aerobic respiration but not in anaerobic respiration.

The correct answer is A (which I understand), but was wondering if someone could explain why D is an incorrect statement?

Thanks

Because NADH is also used in anaerobic respiration. In glycolysis, NAD is an input that with the breakdown of glucose gets converted into NADH. This NADH is then recycled in glycolysis when no oxygen is available to be able to still have some energy output for the body (ATP).
Hope this clears this up for you.

[Comet striker]

I'm having a hard time with the experimental type questions in my practice exams. Any tips to help with this? Some of it is my lack of understanding of how to define a control in an experiment. Sometimes its to set up a baseline for an experiment, sometimes its to confirm the whether the independent variable is only affecting the dependent variable.
Any general tips on experimental design questions
thnx

[IThinkIFailed]

I'm having a hard time with the experimental type questions in my practice exams. Any tips to help with this? Some of it is my lack of understanding of how to define a control in an experiment. Sometimes its to set up a baseline for an experiment, sometimes its to confirm the whether the independent variable is only affecting the dependent variable.
Any general tips on experimental design questions
thnx

This is something I’ve been struggling with as well. I think in the end, the main function of a control is to provide a baseline of results where the independent variable is not affecting the dependent variable.

Thus, through this, you should be able to discern if the independent variable is actually affecting the dependent variable you are testing.  The baseline of results that the answers you see in examiners report I’d say necessarily implies this (I might be wrong, someone please check this)

For example, if you were testing the impact of a drug on plant growth, a control, group you might use is a group of plants not exposed to the drug, but measure their growth anyway. This provides a baseline of results in which the independent variable is not affecting the dependent variable, allowing you to discern if it truly is the IV that’s affecting the DV, and not some other process.

So ultimately, to answer your question, I think baseline of results necessarily implies the whole making sure that the IV effects the DV thing. Personally, I’m going to overwrite a bit and say both parts of the defintion