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March 28, 2024, 07:03:22 pm

Author Topic: VCE Biology Question Thread  (Read 3570264 times)  Share 

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Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #13425 on: April 27, 2021, 10:20:22 pm »
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Incubation of cells at 20 degrees Celsius blocks the release of proteins from the trans- Golgi. Under such conditions you would expect to see
A an increase in exocytosis of proteins
B a decrease in exocytosis if proteins
C an increase in endocytosis of proteins
D a decrease in endocytosis of proteins

Would this be b

Oynx

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Re: VCE Biology Question Thread
« Reply #13426 on: May 02, 2021, 12:14:44 am »
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Can someone highlight the steps need for the cell-mediated immune response? Just need it for clarification. Thanks
2021 - Biology | Further mathematics

Sine

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Re: VCE Biology Question Thread
« Reply #13427 on: May 02, 2021, 07:33:33 am »
+3
Incubation of cells at 20 degrees Celsius blocks the release of proteins from the trans- Golgi. Under such conditions you would expect to see
A an increase in exocytosis of proteins
B a decrease in exocytosis if proteins
C an increase in endocytosis of proteins
D a decrease in endocytosis of proteins

Would this be b
Yeah, it looks like B is correct. Golgi is used for protein export.

Can someone highlight the steps need for the cell-mediated immune response? Just need it for clarification. Thanks
Which aspect were you unsure of?

Oynx

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Re: VCE Biology Question Thread
« Reply #13428 on: May 02, 2021, 05:32:58 pm »
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Yeah, it looks like B is correct. Golgi is used for protein export.
Which aspect were you unsure of?

just the initiation part, do T helper cells activate the cytotoxic t cells without cytotoxic t cells don't binding to the APC, or do the cytotoxic t cells bind to the APC in order to be activated?
2021 - Biology | Further mathematics

Harrycc3000

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Re: VCE Biology Question Thread
« Reply #13429 on: May 02, 2021, 08:05:05 pm »
+4
just the initiation part, do T helper cells activate the cytotoxic t cells without cytotoxic t cells don't binding to the APC, or do the cytotoxic t cells bind to the APC in order to be activated?
I think for cell mediated immunity its like the naiive T cell (which turns to cytotoxic) binds to any bad antigen (MHC 1 marker) and then gets activated by t helper cell. That means it can be via APC (cross presentation of antigen onto MHC 1 or that APC is just virally infected) but its mostly like bad cells specifically, transplant, cancerous or virally infected cells that will present to the naiive T cell and then an activated T helper cell will later encounter that naiive t cell and then activate it through release of cytokines. What I would say is 'cell mentioned in q stem (it will probably be virally infected) presents antigen on MHC 1 marker to naiive t cell/cytotoxic t cell. Activated T helper cell with specific and complementary receptor to x antigen encounters naiive t cell and activates naiive t cell/cytotoxic t cell via release of cytokines and interleukins.' and then go on with the rest of your response.

What I'm trying to say is that APC is not as defining of a feature in cell mediated immunity as humoral immunity. Humoral immunity APCs are important because those antigens are literally swallowed by them in the fluid (humoral) (MHC 2 markers is taken from endosomal compartments) and so they have to present it to those t helper cells whereas for cytotoxic t cells its more about whether the cell is bad or not (MHC 1 marker more important because it shows what you make) and so those tiny peptides that are engulfed aren't what you care about, what you care about is whether the cell is a bad cell or not. (hence the name cell mediated immunity) and so APCs play less of a role because its less practical to swallow a whole cell and then present it compared to just seeing its MHC 1 marker and straight seeing if its a bad cell or not.

This was a bit of a convoluted confusing explanation sorry about that but hopefully you understand what im trying to say!
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Erutepa

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Re: VCE Biology Question Thread
« Reply #13430 on: May 02, 2021, 10:16:18 pm »
+5
just the initiation part, do T helper cells activate the cytotoxic t cells without cytotoxic t cells don't binding to the APC, or do the cytotoxic t cells bind to the APC in order to be activated?
In activation of naive cytotoxic t cells, the APC will bind both the helper t cell and a naive cytotixic t cell specific to that antigen. This cytotoxic t cell will receive stimulation from both the APC and the helper t cell resulting in its clonal selection and subsequent differentiation and proliferation. These activated cytotoxic t cells will then travel throughout the host where they will bind to MHC class I molecules presenting their specific antigen, and initiate the death of these cells through release of perforin to create a pore in the target cell and granzymes which enter through the pore and trigger apoptosis (intrinsic pathway).
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Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #13431 on: May 03, 2021, 10:24:20 pm »
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What exactly is the purpose of the introns

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Re: VCE Biology Question Thread
« Reply #13432 on: May 04, 2021, 10:07:54 am »
+8
What I would say is 'cell mentioned in q stem (it will probably be virally infected) presents antigen on MHC 1 marker to naiive t cell/cytotoxic t cell. Activated T helper cell with specific and complementary receptor to x antigen encounters naiive t cell and activates naiive t cell/cytotoxic t cell via release of cytokines and interleukins.' and then go on with the rest of your response.

What I'm trying to say is that APC is not as defining of a feature in cell mediated immunity as humoral immunity.

While this is probably okay for VCE biology,  I would be cautious about saying APCs are not a fundamental part of cell-mediated immunity. The following stuff is outside the VCE course, but we know that dendritic cells (DC) are really the only cell capable of activating T cells as they have the correct co-stimulatory molecules. Thus, for a T helper or a cytotoxic T cell to be activated, they usually require antigen presentation by a DC (via cross-presentation for MHC I if DC is not infected itself) to be activated (but this is biology and there are always exceptions haha). If a T cell just binds antigen without any co-stimulation it is programmed to die via apoptosis.

So for T helper or cytotoxic T cell to be activated, it does require APCs. And once a T helper is activated it can then help activate a Cytotoxic T cell that is also bound to a DC (sometimes the DC alone does not provide enough activating stimulation and needs 'help').
It is thought that the T helper binds to the DC itself to help further activate the DC which can then better activate the cytotoxic T cell (td;lr immunology is really complex haha so don't worry if this isn't making much sense)!

Importantly, once activated, by usually both an APC and T helper, the cytotoxic T cell can then assert its effector function on a cell presenting the correct antigen on MHC I.

In activation of naive cytotoxic t cells, the APC will bind both the helper t cell and a naive cytotixic t cell specific to that antigen. This cytotoxic t cell will receive stimulation from both the APC and the helper t cell resulting in its clonal selection and subsequent differentiation and proliferation. These activated cytotoxic t cells will then travel throughout the host where they will bind to MHC class I molecules presenting their specific antigen, and initiate the death of these cells through the release of perforin to create a pore in the target cell and granzymes which enter through the pore and trigger apoptosis (intrinsic pathway).

This is a good description for VCE biology. Don't talk about all that dendritic cells stuff I just described! That was just a bit of extra info.

What exactly is the purpose of the introns

While they don't code for the protein they are important for gene regulation. They can also code for things called functional RNAs (not VCE info).
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Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #13433 on: May 04, 2021, 01:46:37 pm »
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The rough endoplasmic reticulum also makes the membranes for organelles that are not in the endomembrane system however the membrane components are transferred to these organelles in other ways.

How are the membrane components transferred to these organelles?

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Re: VCE Biology Question Thread
« Reply #13434 on: May 05, 2021, 08:58:20 pm »
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how much do i need to know about the timeline on earth? do i have to memorise all of the events that occurred like cambrian explosion or when multicellularity occurred and also like the dates when these events happened.

Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #13435 on: May 06, 2021, 08:59:34 pm »
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A protein (found in blood) is produced by the pancreas and acts on receptors on target liver cells. What type of signalling molecule is it most likely to be?
A hormone
B paracrine signal
C a neurotransmitter
D an autocrine signal

It’s found in blood so would it just be a

Sine

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Re: VCE Biology Question Thread
« Reply #13436 on: May 06, 2021, 09:15:26 pm »
+5
A protein (found in blood) is produced by the pancreas and acts on receptors on target liver cells. What type of signalling molecule is it most likely to be?
A hormone
B paracrine signal
C a neurotransmitter
D an autocrine signal

It’s found in blood so would it just be a
Yeah that would be the most correct answer and probably what the question is getting at.

However, the actual signalling type would be endocrine.
« Last Edit: May 06, 2021, 09:17:30 pm by Sine »

tiredandstressed

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Re: VCE Biology Question Thread
« Reply #13437 on: May 06, 2021, 09:16:16 pm »
+4
A protein (found in blood) is produced by the pancreas and acts on receptors on target liver cells. What type of signalling molecule is it most likely to be?
A hormone
B paracrine signal
C a neurotransmitter
D an autocrine signal


It’s found in blood so would it just be a
Correct its A!
But also the hormone is produced in the pancreas and the receptor is in the liver, therefore,
It can't be autocrine since the signal would go back to the same cell and it can't be paracrine since the pancreas and liver are not 'nearby' in this context.
Thus A is most likely to be correct.

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Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #13438 on: May 08, 2021, 07:13:26 pm »
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How do cells know which regions should be classed as introns or exons

Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #13439 on: May 09, 2021, 08:48:51 pm »
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Are the inputs of glycolysis glucose, 2NAD+, 2 ATP, 4 ADP, 2Pi

Or why do some say it’s 2ADP + Pi
When saying where glycolysis takes place would cytosol be more correct than cytoplasm

During glycolysis Aren’t 4 molecules of ADP converted into ATP