VCE Biology Question Thread

[millie96]

how does the humoral response actually initiate? through tH cells and cytokines or binding to an antigen?

[Reus]

No, as in during writing time, can we circle answers on question booklet?

Not too sure about that one.

[katiesaliba]

how does the hum oral response actually initiate? through tH cells and cytokines or binding to an antigen?

Cytokines secreted by T-helper cells stimulate clonal expansion in B-cells, therefore they're necessary for the humoral response to occur

Do we need to know about Barr bodies?

I saw a multiple choice that was about Barr bodies, however all the info you needed was included in the question itself

No, as in during writing time, can we circle answers on question booklet?

I don't see why not, however wouldn't that just be wasting time?

[kk.08]

Heya all, hope last minute revision is going well haha

Does anyone have a good explanation of the term extinction...I've come across this questins in many exams and always have difficulties answering it in the best way possible.

Thanks!

[gunsforhands]

Does anyone have a good explanation of the term extinction...I've come across this questins in many exams and always have difficulties answering it in the best way possible.

Something along the lines of "when there are no members of a particular species left in existence"

[maddihanna]

Heya all, hope last minute revision is going well haha

Does anyone have a good explanation of the term extinction...I've come across this questins in many exams and always have difficulties answering it in the best way possible.

Thanks!

According to last years VCAA exam, the examiners defined it as "when no members of a particular species exist"
But my teacher said for extra detail you should add that "no members of the species have been seen for at least 50 years"
Hope this helps xx

[Jason12]

what's the difference between recombination and independant assortment?

[anat0my]

difference in function b/tw MHC I and II? thanks. 

[Zailiner]

Cytokines secreted by T-helper cells stimulate clonal expansion in B-cells, therefore they're necessary for the humoral response to occur

So, B cells cannot initiate clonal expansion without the stimulation from cytokines?

So what happens if a B-cell encounters an antigen? If I recall correctly, it will present the antigen to a T-helper cell via its MHC class II markers,
which will confirm the antigen as a foreign object and the T-helper will then release cytokines? Or am I completely wrong?

[Coralista]

what's the difference between recombination and independant assortment?

Independent assortment results in genetic recombination. Recombination is the re-assortment of genetic material to produce new variations (when populations show variation that are not present in their parents). Whereas independent assortment is when two pairs of chromosomes line up on the equator at a completely random position, in metaphase I of meiosis

[Coralista]

So, B cells cannot initiate clonal expansion without the stimulation from cytokines?

So what happens if a B-cell encounters an antigen? If I recall correctly, it will present the antigen to a T-helper cell via its MHC class II markers,
which will confirm the antigen as a foreign object and the T-helper will then release cytokines? Or am I completely wrong?

You are correct. Antigens will bind to the B-cell receptor which leads to the B-cell presenting the antigen on its surface, hence allowing the T helper cells to secrete interleukins for B-cell activation. 

[Reus]

Are we allowed to write in red pen? Like for subheadings when constructing an experimental design and such...

[heymanhru]

Are there any differences between recombination and crossing-over? Are the terms interchangeable?

[Coralista]

Are we allowed to write in red pen? Like for subheadings when constructing an experimental design and such...

I don't see why not, I mean as long as they don't disappear during the scanning process it should be fine.. I think..

[Coralista]

Are there any differences between recombination and crossing-over? Are the terms interchangeable?

Crossing over results in recombination. As I mentioned in one of the earlier posts, recombination is the re-assortment of genetic instructions present in an organism, this isn't necessarily the exact same thing as crossing-over. As crossing-over is the exchange of genetic material between non-sister chromatids.