VCE Biology Question Thread

[PhoenixxFire]

The free antigens come from peptide fragments that have broken off (eg when a virus is moving between cells).

We were always taught the APC binds with antibody receptor on B cell but cannot do anything until a Th also binds and then releases the cytokines ?

B cells do not need APC's only Th cells do. They cannot divide and differentiate until the Th cell releases cytokines (as a result of them binding the same antigen).

[pink sharpie]

Could someone please explain the different hypersensitivity reactions (type 2,3 and 4) please!!

[PhoenixxFire]

Could someone please explain the different hypersensitivity reactions (type 2,3 and 4) please!!

They aren't in the study design. We only need to know about the allergic response (type 1).

[ezferns]

Can steroids bind to a receptor in the nucleus? I feel like I've seen this somewhere but VCAA always just says they bind to a receptor in the cytosol.
Also what is wrong with saying 'the receptor for the steroid hormone was within the cell' for Q5c 2010 E1
http://www.vcaa.vic.edu.au/Documents/exams/biology/biology1_assessrep_10.pdf

[vox nihili]

Can steroids bind to a receptor in the nucleus? I feel like I've seen this somewhere but VCAA always just says they bind to a receptor in the cytosol.
Also what is wrong with saying 'the receptor for the steroid hormone was within the cell' for Q5c 2010 E1
http://www.vcaa.vic.edu.au/Documents/exams/biology/biology1_assessrep_10.pdf

Nope. The steroid receptor is within the cytoplasm.
Probably beyond VCE, but it’s a weird receptor in that it’s in the cytoplasm and once it’s bound to the steroid hormone, it goes into the nucleus.

I suspect that the within the cell is wrong because it’s not specific enough.

[ezferns]

Thanks!
Another quick question: In gene therapy, are functional alleles integrated into the nuclear DNA?

[parharjasmine]

Hello,

Can anyone explain the following two questions:

- why do some vaccines need booster shots?
- why do allergic response become worse after subsequent exposures to an allergen?

Thank you in advance

[PhoenixxFire]

Thanks!
Another quick question: In gene therapy, are functional alleles integrated into the nuclear DNA?

Yep!

Hello,

Can anyone explain the following two questions:

- why do some vaccines need booster shots?
- why do allergic response become worse after subsequent exposures to an allergen?

Thank you in advance

Some vaccines need boosters shots because the number of memory cells decline faster.

Allergic responses become worse because each subsequent reaction produces more antibodies against it, which causes a larger reaction at next exposure.

[vox nihili]

Here's a fun question:


Why do we treat allergies by exposing people to small doses of allergen?

[ezferns]

Here's a fun question:


Why do we treat allergies by exposing people to small doses of allergen?

It it to increase the number of circulating antibodies and hence decrease the chance of allergens binding to antibodies on mast cells, causing an allergic reaction?

[ezferns]

Does salt water affect the chance of fossilisation?

[rainbowsparkles15]

Here's a fun question:


Why do we treat allergies by exposing people to small doses of allergen?

Does the allergen bind to already existing IgE antibodies in the body, meaning less antibodies are available to bind to allergens upon future contact??
Just guessing!!

Also, could someone please help me understand question 11 multiple choice, VCAA 2014?
Thank you!!

[medsci]

Does the allergen bind to already existing IgE antibodies in the body, meaning less antibodies are available to bind to allergens upon future contact??
Just guessing!!
Also, could someone please help me understand question 11 multiple choice, VCAA 2014?
Thank you!!

Basically this question is testing you on your understanding of osmosis. In the base on the question they tell you that as the trap shuts, the potassium ions leave the trap. This means that water molecules will also move out of the trap from an area of low solute concentration to an area of high solute concentration by osmosis, hence the option D is correct. This would cause the plant trap to collapse due to the cells becoming plasmolysed. Hope this helps!

[vox nihili]

I really like the ideas so far about immunotherapies, they're essentially correct. By introducing allergens this way, you actually make an IgG response (the reasons for this are well beyond VCE). If you keep exposing, you get more and more and more IgG. Eventually, there's so much IgG that when the body encounters an allergen, the IgG scoops up all the allergen before before it can reach IgE and cause allergy

[Seno72]

Hello guys. I just want to ask a few questions:

When steroid hormones bind to receptors on cytoplasm, does a cascade reaction/signal amplification occur or doesn't that only occur for protein based hormones?

Also, is it required that we need know the blood types?