VCE Biology Question Thread

[Evolio]

Thanks Erutepa for the previous help. I got confused.

I had a question regarding the 2018 Biology exam. For question 9 b, I wrote smaller teeth which are less sharp, allowing the organism to feed on smaller fish and that it has leg appendages that would allow the organism to move and walk on land.
Is this first point too vague?

[Erutepa]

Thanks Erutepa for the previous help. I got confused.

I had a question regarding the 2018 Biology exam. For question 9 b, I wrote smaller teeth which are less sharp, allowing the organism to feed on smaller fish and that it has leg appendages that would allow the organism to move and walk on land.
Is this first point too vague?

The examiner's report states that in order to justify the fossil as a transitional fossil, you need to identify 1 aquatic adaptation and 1 terrestrial adaptation. The leg appendages is a great terrestrial adaptation, but the smaller teeth (in my opinion) aren't a great aquatic adaptation. Since you justified that it allows feeding on fish, you might be awarded the marks, but I don't think smaller teeth are necessarily an aquatic adaptation since there are plenty of terrestrial animals with small and less sharp teeth. I would personally recommend going with a more clearly aquatic feature such as the presence of fins or webbed appendages which allow for movement through the water. Once again, I am not sure about whether your response might get the marks, but I think there are more obvious aquatic features you could have chosen.

[sandywu]

Hi, I was wondering if the negative feedback loop is still in the current study design?

[Evolio]

Not in units 3 4  but it is there in Unit 1 Area of study 2.

[Bri MT]

The examiner's report states that in order to justify the fossil as a transitional fossil, you need to identify 1 aquatic adaptation and 1 terrestrial adaptation. The leg appendages is a great terrestrial adaptation, but the smaller teeth (in my opinion) aren't a great aquatic adaptation. Since you justified that it allows feeding on fish, you might be awarded the marks, but I don't think smaller teeth are necessarily an aquatic adaptation since there are plenty of terrestrial animals with small and less sharp teeth. I would personally recommend going with a more clearly aquatic feature such as the presence of fins or webbed appendages which allow for movement through the water. Once again, I am not sure about whether your response might get the marks, but I think there are more obvious aquatic features you could have chosen.

I haven't read the question but I definitely agree about smaller, blunter teeth not being an aquatic adaptation.

Fins & webbed appendages are good aquatic adaptations, you could also consider things like:
- streamlined body shape
- buoyancy control adaptations such as a swim bladder
- presence of gills
- salt glands
- increased lung capacity

make sure if you use any of these you check it's applicable to the scenario - e.g. wouldn't make sense to suggest a plant having many of these

[xenx]

hi,
just a few questions:
1. Some exams I've done state T cells as giving rise to Helper t cell, cytotoxic T cell and memory cells? Isn't it suppose to be activated t helper give rise to more activated t helper cell and memory helper t cell etc.
2. Also on a few of the vcaa exams, there has been questions about giving vaccines to viral infections, however aren't vaccine specifically suppose to make memory B cells that give rise to plasma cell which secrete antibodies. Don't antibodies aid in destroying cellular pathogen rather than non-cellular pathogens. How does vaccine work with viral infection?
3. is it correct to say a structural feature that occurred as hominids evolved into modern humans would be smaller teeth due transition of lifestyle - herbivore to omnivore
4. Do NK cells also release granzymes and perforins to initiate apoptosis and are they also involved in transplant rejection
5. How is pigment (from tattooing) identified as foreign by macrophages and why is there no adaptive response to the ink pigments by the body?
Thanks xx

[Livcur16]

Hi, I am a bit confused as to when cytokines are used within the immune response, and why and when they activate other immune cells.
Thanks

[Chocolatemilkshake]

Hi, I am a bit confused as to when cytokines are used within the immune response, and why and when they activate other immune cells.
Thanks

I'll try my best to answer 

Cytokines are signalling molecules used in communication between immune cells.

Different cytokines achieve different things. For instance, interferons are a type of cytokine released from a virally-infected cell that makes nearby cells more resistant to viral infection.

Cytokines are also released by Helper T cells (Interleukins) when a Helper T cell binds to an antigen via its specific T cell receptor. These cytokines then activate selected B cells or Cytotoxic T cells (that are specific to the same antigen), causing them to proliferate and B cells to differentiate into plasma B cells and Memory B cells. Without cytokines, specific B cells and Cytotoxic T cells would not proliferate when needed by the immune system.

[Livcur16]

I'll try my best to answer 

Cytokines are signalling molecules used in communication between immune cells.

Different cytokines achieve different things. For instance, interferons are a type of cytokine released from a virally-infected cell that makes nearby cells more resistant to viral infection.

Cytokines are also released by Helper T cells (Interleukins) when a Helper T cell binds to an antigen via its specific T cell receptor. These cytokines then activate selected B cells or Cytotoxic T cells (that are specific to the same antigen), causing them to proliferate and B cells to differentiate into plasma B cells and Memory B cells. Without cytokines, specific B cells and Cytotoxic T cells would not proliferate when needed by the immune system.

Thanks so much! Also, when are they used in the 2nd line of defense?

[Chocolatemilkshake]

Thanks so much! Also, when are they used in the 2nd line of defense?

Interferons (type of cytokine) are part of the innate immune system (second line of defence) as they are non-specific. Meaning no matter what type of virus, the interferon released from the virally infected cells will still result in the same response (defences against viruses).

[Chocolatemilkshake]

I've come across some discrepancy regarding the pelvis trend from the Genus Australopithecus to Homo.

In VCAA 2013 Q11a. It states that the Australopothicus pelvis is wider than Neanderthals, indicating that the trend is the pelvis becoming narrower. However, I've done some company exams which state that the pelvis actually becomes broader from Australopithecus to Homo.

Would love someone to clear that up for me 

[Erutepa]

hi,
just a few questions:
1. Some exams I've done state T cells as giving rise to Helper t cell, cytotoxic T cell and memory cells? Isn't it suppose to be activated t helper give rise to more activated t helper cell and memory helper t cell etc.
2. Also on a few of the vcaa exams, there has been questions about giving vaccines to viral infections, however aren't vaccine specifically suppose to make memory B cells that give rise to plasma cell which secrete antibodies. Don't antibodies aid in destroying cellular pathogen rather than non-cellular pathogens. How does vaccine work with viral infection?
3. is it correct to say a structural feature that occurred as hominids evolved into modern humans would be smaller teeth due transition of lifestyle - herbivore to omnivore
4. Do NK cells also release granzymes and perforins to initiate apoptosis and are they also involved in transplant rejection
5. How is pigment (from tattooing) identified as foreign by macrophages and why is there no adaptive response to the ink pigments by the body?
Thanks xx

1) I am not aware of VCAA saying T cells differentiate to give rise to Helper t cell, cytotoxic T cells - do you know what exams mentioned this?. I have found them defining that "T memory cells survive for many years and proliferate rapidly into Th and Tc cells when the body is exposed to a pathogen for the second time, mounting a quicker and stronger response".
Helper T cells will differentiate to produce more helper T cells and memory helper T cells, but VCAA doesn't seem to want you to make the distinction between the two types of memory T cells, and instead wants you to group them as 'T memory cells'.

2)Antibodies are still effective against viruses. The humoral immune system may be activated by viral antigens and antibodies specific to these viral antigens can be produced where they will bind to the virus itself function to:
 - neutralise the virus (i.e. by antibody binding to a surface protein (of the virus) which enables the virus to bind to host cells, thus preventing the virus from binding to host cells and replicating).
 - Agglutinate virus particles, preventing their movement through the body
 - act as an opsonin and enhance phagocytosis of the virus

3) I would agree with this response

4) NK cells do release perforin and granzymes. NK cells do play a role in tissue rejection - but I think most questions will want you to talk about cytotoxic T cells.

5) This question is a bit odd - was there more context that came with it?

[1292]

hi, are MHC Class I and 2 markers proteins or carbohydrates? I initially thought they were proteins but glycoproteins are responsible for cell-to-cell recognition - is that referring to MHC markers or something else?

[Erutepa]

hi, are MHC Class I and 2 markers proteins or carbohydrates? I initially thought they were proteins but glycoproteins are responsible for cell-to-cell recognition - is that referring to MHC markers or something else?

MHC class I and II receptors are protein complexes.
There are other glycoproteins that play roles in cell to cell recognition though.

[Evolio]

I've come across some discrepancy regarding the pelvis trend from the Genus Australopithecus to Homo.

In VCAA 2013 Q11a. It states that the Australopothicus pelvis is wider than Neanderthals, indicating that the trend is the pelvis becoming narrower. However, I've done some company exams which state that the pelvis actually becomes broader from Australopithecus to Homo.

Would love someone to clear that up for me 

From Australopithecus to Homo, the pelvis becomes more bowl-shaped and if you look at the images they provided on the exam, the pelvis does jut out less in the neanderthal skeleton and the pelvis is more taller and narrower. I'm not sure why there is a discrepancy though.