VCE Biology Question Thread

[BakedDwarf]

Yes, macrophages are not the only Antigen Presenting Cells. You also have dendritic cells that present antigens on their MHC II markers. There are three APCs: B cells, Dendritic cells and macrophages. Only these three cells actually engulf foreign material and present antigenic fragments on their MHC II markers. xD

B cells also have MHC II. Works the same as a macrophage as far as I know

I know that dendritic cells and macrophages engulf pathogens, but do b-cells also engulf pathogens?

[jyodesh.com]

I know that dendritic cells and macrophages engulf pathogens, but do b-cells also engulf pathogens?

B-cells aren't phagocytic no, but once an antigen is bound to the B-cell receptor, it can internalise it and present it in the groove of MHCII

[paper-back]

Is a second messenger synthesised in the signal transduction pathway of both lipid soluble and insoluble hormones?
Is a G-Protein just a surface membrane receptor?
Can MHC markers be present on pathogens?

[Biology24123]

Yes, macrophages are not the only Antigen Presenting Cells. You also have dendritic cells that present antigens on their MHC II markers. There are three APCs: B cells, Dendritic cells and macrophages. Only these three cells actually engulf foreign material and present antigenic fragments on their MHC II markers. xD

Some epithelial cells are antigen presenting.

[jyodesh.com]

Some epithelial cells are antigen presenting.

From what I'm aware of this is only in the thymus for T-cell development

[vox nihili]

The details of which cells are APCs is relatively unimportant. There are actually quite a few, but the most important is the dendritic cell, with macrophages also playing a pretty vital role too.

Is a second messenger synthesised in the signal transduction pathway of both lipid soluble and insoluble hormones?
Is a G-Protein just a surface membrane receptor?
Can MHC markers be present on pathogens?

Depends on the individual pathway. Oftentimes, lipid soluble hormones will interact with a chaperone, which in turn takes it straight to its gene target (therefore no second messenger). This is well and truly out of the VCE course though.

No. G-proteins are cytosolic. They are activated by G-protein coupled receptors (GPCRs). Again, well and truly outside of the course. Long story short though, G-proteins are second messengers in essence.

No.

[BakedDwarf]

What do we need to know about a eukaryotic cell's cytoskeleton??

 Is knowing that the cytoskeleton is a network of protein fibres which provide structural support, anchorage, shape, motility and a capacity to move and arrange organelles within the cell sufficient? (i got this definition off a website, not sure if it's right though)

[vox nihili]

What do we need to know about a eukaryotic cell's cytoskeleton??

 Is knowing that the cytoskeleton is a network of protein fibres which provide structural support, anchorage, shape, motility and a capacity to move and arrange organelles within the cell sufficient? (i got this definition off a website, not sure if it's right though)

Yep, that's more than enough.

[cosine]

B-cells aren't phagocytic no, but once an antigen is bound to the B-cell receptor, it can internalise it and present it in the groove of MHCII

B cells are phagocytic, not sure where you got this from??

[cosine]

How can viruses protect themselves from interferons?
I assume that their viral genome contains genes for the expression of defense proteins/enzymes from these interferons?

[cosine]

Some epithelial cells are antigen presenting.

Out of study design this or?

[cosine]

What term describes the process of copying a gene?
Why can't the answer to this be DNA replication?

What is a probe?
Are ALL probes DNA probes? Because DNA probe was not specified, I assumed a probe was any molecule that 'tags' or marks another molecule. What do you say?

Thank you

[paper-back]

Depends on the individual pathway. Oftentimes, lipid soluble hormones will interact with a chaperone, which in turn takes it straight to its gene target (therefore no second messenger). This is well and truly out of the VCE course though.

In the scope of VCE do we state that a second messenger protein is synthesised?
A component of the answer to one of the questions on a VCAA exam stated that a "second messenger protein is synthesised"

[mahler004]

In the scope of VCE do we state that a second messenger protein is synthesised?
A component of the answer to one of the questions on a VCAA exam stated that a "second messenger protein is synthesised"

That's not true - the signal transduction pathway basically is:

Ligand binds to GCPR -> GCPR activates G protein -> A second messenger is produced.

(I've left out a few steps).

There are examples of second messenger proteins, but they aren't produced as a response to a signal (they are activated.)

(edit: forgot about a pathway).

But yeah. What T-Rav said. Signal transduction is really, really complicated. By necessity, it's simplified here.

What is a probe?
Are ALL probes DNA probes? Because DNA probe was not specified, I assumed a probe was any molecule that 'tags' or marks another molecule. What do you say?

A probe can mean a lot of things, but if the question is talking about DNA, it's probably fair to assume it's a DNA probe.

[cosine]

That's not true - the signal transduction pathway basically is:

Ligand binds to GCPR -> GCPR activates G protein -> A second messenger is produced.

(I've left out a few steps).

There are examples of second messenger proteins, but they aren't produced as a response to a signal (they are activated.)

(edit: forgot about a pathway).

A probe can mean a lot of things, but if the question is talking about DNA, it's probably fair to assume it's a DNA probe.

Attached is the question, indeed the next part talks about DNA, but honestly is this ambiguous or not because I really have a problem here because I always lose marks because of trying to be specific, like I knew exactly what a DNA probe is, single stranded DNA molecule that binds to the complementary DNA strand to mark it so it can be monitored, but I purposely did not write that because the question did not ask for the definition of DNA probe, but simply just probe. Honestly, what should I do to avoid stuff like this? Really disheartening knowing I am susceptible to easy marks like this