VCE Biology Exam - 01/11/19 - Discussion/Questions/Solutions

[3086]

cause it diffuses out from grana to stroma to outside as it is an output

[Erutepa]

For the photosynthesis question, why was there high O2 conc. when the plant was photosynthesising in Region  R(stroma) than when plant was not photosynthesising. Doesn't the splitting of H2O occur in thylakoid membranes to form O2 in light dependant stage? Then, how can O2 be in stroma?

This question asked you to say why there would be a higher concentration of oxygen in the stroma when photosynthesis is occurring compared to when it isn't. You are right in saying that the formation of oxygen does occur on in the thylakoid lumen, but oxygen will diffuse into the stroma and increase the oxygen concentration during photosynthesis. However, oxygen will not be produced/diffuse into the stroma when photosynthesis is not occurring, hence why there is a higher concentration of oxygen during photosynthesis

[PhoenixxFire]

Hey,
Attached to this post is a pdf containing all of the suggested solutions written by me and Erutepa.

As always, feel free to question any of this if it doesn't make sense or you think we got something wrong. There were some questions (e.g. the one on bmp4) that were quite...open to interpretation. The solutions we've written are written as full paragraphs - this does not mean that you need to have written exactly the same thing as us to get the marks. They're just one possible way to write it - use them as a guide as to the type of information that was required.

In order to see and download the attachment, you need to be logged in.


I'll go through and answer the questions that have come up so far in a minute, I need to eat dinner first though haha

[Erutepa]

For question 1 wasn't molecule 1 tRNA and molecule 2 DNA?

That's exactly right - that's definitely a mistake in our solutions - we will edit it with the correct solution.
The molecules are a tRNA molecules and a DNA molecule

[cookielife]

Hey,
Attached to this post is a pdf containing all of the suggested solutions written by me and Erutepa.

As always, feel free to question any of this if it doesn't make sense or you think we got something wrong. There were some questions (e.g. the one on bmp4) that were quite...open to interpretation. The solutions we've written are written as full paragraphs - this does not mean that you need to have written exactly the same thing as us to get the marks. They're just one possible way to write it - use them as a guide as to the type of information that was required.

In order to see and download the attachment, you need to be logged in.


I'll go through and answer the questions that have come up so far in a minute, I need to eat dinner first though haha

For question 10b in short answer, can you get the marks if you said that mtDNA mutates more often because of no repair mechanisms, therefore nuclear DNA is more representative of divergence to determine evolutionary relationships?

[PhoenixxFire]

For question 1 wasn't molecule 1 tRNA and molecule 2 DNA?

Sorry I should have had a coffee before I started writing. Have fixed it.

[Erutepa]

For question 10b in short answer, can you get the marks if you said that mtDNA mutates more often because of no repair mechanisms, therefore nuclear DNA is more representative of divergence to determine evolutionary relationships?

While the higher mutation rate is a difference between the two, I don't think your justification is sufficient. Just because nuclear DNA has a lower mutation rate doesn't mean its necessarily better to determine evolutionary relationships. You might get away with saying that a lower mutation rate makes it good for tracing distant evolutionary relationships as mRNA may have possessed too many mutations to be used accurately, but I don't think I would consider the example given as distant evolutionary relationships.
This question was an odd one I think, and the only viable reason I could think of was the example solution given.

Haha thats okay, for 8c. could temperature be considered a factor that affects  the migration  of DNA through the gel? (i.e at low temperatures the DNA may move very slowly)

I think that would be a valid response!

[Abby Xiaaaaa]

Sorry I should have had a coffee before I started writing. Have fixed it.

How many marks was the table in the first question worth?
Thanks

[dev_xy]

with 9.c. would it be okay if you mentioned the scientist used Immunosorbent Assay test..
the test is conducted with the heavy chains which remain constant.. or something

[PhoenixxFire]

How many marks was the table in the first question worth?
Thanks

2. You would have gotten one mark for each difference.

[dev_xy]

But I doubt that the examiners- bio teachers would know what a immunosorbent Assay is ... my teacher didn't when I told her that that's what I put lol

[Erutepa]

with 9.c. would it be okay if you mentioned the scientist used Immunosorbent Assay test..
the test is conducted with the heavy chains which remain constant.. or something

You could say this, however its important that you explain how it only detects the constant region and that the constant region is essentially identical for all antibodies. It's the explanation that will get the mark - not stating the assay.

[will.i.am.s_arah]

Would histamines count as a protein if you didn't say IgE?

[Erutepa]

Would histamines count as a protein if you didn't say IgE?

The question wording indicates the protein involve interacts with the pollen fragments. Histamine doesn't really interact with the pollen fragments while IgE antibodies do. There is a chance they may award the mark if you said histamine, but I wouldn't be surprised if they take that as an incorrect solution, unfortunately.

[tdowler100]

Would heparin count for the chemical barrier question??