VCE Biology Question Thread

[jessica666]

Also what does it mean by "desensitisation" when referring to immunotherapy? Thanks.

Desensitisation involves exposing a person to small amounts of the allergen. Each time the person is exposed, the allergen binds to antibodies, decreasing the number of antibodies available for future reactions

[That Other Guy]

Would this be considered an adequate explanation of allopatric speciation?

The populations are isolated geographically by a permanent barrier. Hence, no gene flow occurs between them.
The populations are subjected to different environments and thus selective pressures.
When brought back together, if the populations do not interbreed to produce viable offspring, they are different species.

[katiesaliba]

Would this be considered an adequate explanation of allopatric speciation?

The populations are isolated geographically by a permanent barrier. Hence, no gene flow occurs between them.
The populations are subjected to different environments and thus selective pressures.
When brought back together, if the populations do not interbreed to produce viable offspring, they are different species.

This is just being pedantic, but I'd also mention that the different selection pressures favour different phenotypes.

[Reus]

Desensitisation involves exposing a person to small amounts of the allergen. Each time the person is exposed, the allergen binds to antibodies, decreasing the number of antibodies available for future reactions

Is this performed to reduce the severity of the allergic response? As it can be detrimental to self tissue? Thanks

Thankyou! But I did not know mast cells where APCs??

Oops ye they're not haha.

Pretty sure it's just the process of making someone less 'sensitive' (may want to use a different word), to negative immune responses such as allergies. An example of this would be (i think) exposing children to nuts etc to reduce risk of allergic response?

Thanks.

[katiesaliba]

Could Australopithecus handle tools?

See attached for question 7a.iii.
I thought it would be 16?
Because 2 x 4 x 2?
(2 - sex chromosomes, 4 - remaining chromosomes, 2 - other 2 to be selected from)

Thanks.

Homo Habilis were the first tool markers.

Homologous chromosomes can assort 2 ways. Therefore, as there are three homologs present, 2x2x2=8. Independent assortment concerns metaphase I, so there are 3 homologs (homologous chromosomes). The actual amount of chromosomes doesn't matter (well, it does but yeah aha) because, during mitosis for example, chromosomes will not independently assort before both sister chromatids are identical copies of each other.

[Jason12]

Did Homo sapiens evolve from erectus or heidelbergensis


Does recombination occur in prophase 1 and independant assortment in anaphase 2

[katiesaliba]

Okay, do cells that have been virally infected undergo necrosis? Can someone briefly describe what we need to know about apoptosis 

[jessica666]

Is this performed to reduce the severity of the allergic response? As it can be detrimental to self tissue?

Yep i'm pretty sure! I think that the first few treatments can have side effects such as inflammation

[Reus]

Insight's trial exam is soooo out of control to the SD lol ._.

[That Other Guy]

Okay, do cells that have been virally infected undergo necrosis? Can someone briefly describe what we need to know about apoptosis 

I wouldn't say so. The cell is not damaged beyond repair, per se, but rather, just overrun. Virally infected cells are usually destoryed via apoptosis.
All we need to know about it is that it is controlled by genes, and may be elicited by an extracellular signal (such as cytokines released by cytotoxic T cells) or intracellular signals, such as heat or radiation. Apoptosis involves the destruction of the entire cell, not just the organelles.Too much apoptosis can lead to atrophy.

I believe that is all.

[katiesaliba]

Is anybody else freaking out? 

[anat0my]

How to draw a pedigree for X-linked recessive? thanks!

[Reus]

How to draw a pedigree for X-linked recessive? thanks!

Have an affected mother with all affected sons.

[Reus]

Is anybody else freaking out? 

And yes

[TimewaveZero]

I wouldn't say so. The cell is not damaged beyond repair, per se, but rather, just overrun. Virally infected cells are usually destoryed via apoptosis.
All we need to know about it is that it is controlled by genes, and may be elicited by an extracellular signal (such as cytokines released by cytotoxic T cells) or intracellular signals, such as heat or radiation. Apoptosis involves the destruction of the entire cell, not just the organelles.Too much apoptosis can lead to atrophy.

I believe that is all.

Can organelles be recycled?