VCE Biology Question Thread

[althepal]

So then do we need to know what unwinds the dna during transcription?

[mahler004]

That's DNA helicase and is involved in DNA replication, not transcription.

RNA polymerase synthesises a new mRNA strand from a DNA template.

RNA polymerase has helicase activity (it can unwind DNA.) Unlike DNA replication, there's no separate helicase (this is for prokaryotes, I'm pretty sure the same thing happens in eukaryotes, although I'm also fairly sure that eukaryotic transcription isn't in the syllabus.)

Look at section 28.1.3, or figure 28.7

(Usual caveat - that's a second or third year level university biochemistry textbook, much of it's irrelevant for VCE.)

[grannysmith]

A question of my own:
How does the immune system recognise 'self'? Obviously this would include both cells and any kind of protein molecule.

So would it be correct to say that "immune cells have specific receptors that are able to distinguish between different kinds of protein markers (e.g. MHC on cells). If the protein marker is the same as the ones on B and T cells, then the molecule is identified as 'self'. "

But wouldn't other non-specific cells of the immune system (NK cells, macrophages, neutrophils etc.) be able to detect such 'non-self' molecules in the same fashion? Or would it better to stick to the umbrella term of "immune cells'?

And if I wanted to be more specific, would the following be accurate:

"All cells have specific protein markers on their cell membranes. If it is specifically complementary (?) to the Major Histocompatibility Complex (MHC) marker of an immune cell, then it is identified as 'self' cell. If not, then it is identified as 'non self' and a foreign antigen which triggers an immune response."

Surely, the same procedure would be applied to any protein molecule?

Thanks

[katiesaliba]

Is the content covered in question 2 of the 2004 exam 1 (http://www.vcaa.vic.edu.au/Documents/exams/biology/2004biol1.pdf) still relevant to the current study design? 

[Reus]

Is the content covered in question 2 of the 2004 exam 1 (http://www.vcaa.vic.edu.au/Documents/exams/biology/2004biol1.pdf) still relevant to the current study design? 

I haven't seen any post 2006, however I hope so I find plant hormones to be easy.

[katiesaliba]

I haven't seen any post 2006, however I hope so I find plant hormones to be easy.

Oh okay, well I don't. ahaha can someone please clarify? 

[vox nihili]

Is the content covered in question 2 of the 2004 exam 1 (http://www.vcaa.vic.edu.au/Documents/exams/biology/2004biol1.pdf) still relevant to the current study design? 

Nah that's definitely not examined anymore.

[katiesaliba]

Which VCAA unit 3 exams are most relevant to the current study? Would the later years (say 2010 and later) be more beneficial to complete? Because I keep printing out exams and completing only half as most of the questions are irrelevant 

[katiesaliba]

Here's a screenshot from VCAA's FAQ. Just to clarify, does this mean that we have to know the function of each plant hormone or not? Thanks 

[LiquidPaperz]

you guys started on VCAA exams yet?

[Reus]

Which VCAA unit 3 exams are most relevant to the current study? Would the later years (say 2010 and later) be more beneficial to complete? Because I keep printing out exams and completing only half as most of the questions are irrelevant 

≥2006

[Sup]

Do we need to know about the different forms of mutation like substitution mutations, frameshift mutations, etc?

[kk.08]

What is the role of cholesterol in the plasma membrane?

[Tyleralp1]

What is the role of cholesterol in the plasma membrane?

Cholesterol's primary role is to regulate the fluidity and flexibility of the plasma membrane. This is done by preventing it from bunching up, and freezing in cold conditions. Conversely, it keeps the phospholipids closer together in cases of high temperature to prevent it from breaking or loosing its selective permeability.

[Tyleralp1]

Do we need to know about the different forms of mutation like substitution mutations, frameshift mutations, etc?

Indeed we are required to know the various forms of a mutation. These include a single base substitution, addition, or deletion. This may lead to a frameshift mutation, whereby everything is shifted across, or a mutation in which the final protein isn't effected as the same amino acid is produced. Furthermore, a knowledge of chromosome mutations is somewhat needed, such as a chromosome mutation involves many base pairs and significantly alters protein functioning.