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August 24, 2019, 05:35:53 am

Author Topic: VCE Biology Question Thread  (Read 1309407 times)  Share 

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EllingtonFeint

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Re: VCE Biology Question Thread
« Reply #11040 on: October 28, 2018, 10:12:37 am »
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Is it okay to say that TAQ polymerase enzyme uses the primers as an anchor to replicate each strand?
What would be better wording??
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11041 on: October 28, 2018, 10:14:16 am »
+2
Is it okay to say that TAQ polymerase enzyme uses the primers as an anchor to replicate each strand?
What would be better wording??
I would say that it uses them as a starting point to build a complementary strand.

Edit: complementary to the strand the primer is attached to, not complementary to the primer. Be careful how you word that.
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missile

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Re: VCE Biology Question Thread
« Reply #11042 on: October 28, 2018, 10:54:44 am »
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Does photosynthesis not occur at all in plants when exposed only to green light (since it is not really absorbed by chlorophyll), or is does it happen at a very small rate due to the assistance of accessory pigment like carotenoids and phycoerythrin which can absorb those wavelengths?

Thanks
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11043 on: October 28, 2018, 11:09:08 am »
+2
Does photosynthesis not occur at all in plants when exposed only to green light (since it is not really absorbed by chlorophyll), or is does it happen at a very small rate due to the assistance of accessory pigment like carotenoids and phycoerythrin which can absorb those wavelengths?

Thanks
Yeah it would still occur a little (also it’s hard to setup an experiment that only has green light - something like cellophane is still going to let other wavelengths in).

If you get a question about this on the exam I think it’ll probably be a graph that you have to interpret, in which case just use the information you’re given. If the graph says 0 then go with it, if it’s not 0 then just say the lowest rate of photosynthesis occurs under the green light.
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EllingtonFeint

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Re: VCE Biology Question Thread
« Reply #11044 on: October 28, 2018, 12:07:13 pm »
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If a hormone is water soluble, doesn’t that mean that it is polar, so it wouldn’t be able to passively diffuse into a cell?

Can you use “&” instead of the word “and” in a (bio) exam
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11045 on: October 28, 2018, 12:12:36 pm »
+2
If a hormone is water soluble, doesn’t that mean that it is polar, so it wouldn’t be able to passively diffuse into a cell?

Can you use “&” instead of the word “and” in a (bio) exam
It may be able to travel through facilitated diffusion, which is passive. It won't be able to travel via simple diffusion though.

Yeah you can.
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Re: VCE Biology Question Thread
« Reply #11046 on: October 28, 2018, 12:37:59 pm »
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What's the difference between a dendritic cell and a macrophage? Is that a distinction we need to know? And if I explain the body's response to an antigen with a "dendritic cell", but the written answer says "macrophage", do I lose the mark or is the distinction not an issue?
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vox nihili

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Re: VCE Biology Question Thread
« Reply #11047 on: October 28, 2018, 12:39:53 pm »
+4
What's the difference between a dendritic cell and a macrophage? Is that a distinction we need to know? And if I explain the body's response to an antigen with a "dendritic cell", but the written answer says "macrophage", do I lose the mark or is the distinction not an issue?

Not really a distinction you have to know in VCE Biology. Dendritic cell should only be used when you're talking about presentation of antigens to T-helper cells. If the question is about the phagocytic removal of dead bacteria etc then you should use macrophages

EDIT: just to add some post-VCE knowledge.

The purpose of dendritic cells is to sample the environment. They phagocytose stuff all around the joint, and then they take little bits of what they've broken down and place it on MHC-II molecules. If they pick up a bacterial antigen, for example, they'll cruise along to the lymph node and show this to the helper T-cells there.

Macrophages, on the other hand, do all the grunt work. They just eat for a living, breaking down all of the dead shit and bacteria around.

So as above, when phagocytosis is the point you're making, talk about macrophages. Dendritic cells have only just started to appear in the course, and they're only really ever talked about when we talk about presentation to T-cells.

It may be able to travel through facilitated diffusion, which is passive. It won't be able to travel via simple diffusion though.

Yeah you can.

Theoretically they can, but they don't. Typically water soluble hormones are large proteins, so they're too big for carrier proteins or channels. They exit by exocytosis normally.
« Last Edit: October 28, 2018, 12:47:25 pm by vox nihili »
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EllingtonFeint

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Re: VCE Biology Question Thread
« Reply #11048 on: October 28, 2018, 01:05:35 pm »
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What is the link reaction? (Something to do with cellular respiration) Is it relevant to the exam?
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vox nihili

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Re: VCE Biology Question Thread
« Reply #11049 on: October 28, 2018, 01:11:53 pm »
+1
What is the link reaction? (Something to do with cellular respiration) Is it relevant to the exam?

Irrelevant
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C14M8S

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Re: VCE Biology Question Thread
« Reply #11050 on: October 28, 2018, 01:36:12 pm »
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1) Should the link reaction be simply classed as part of the Krebs' cycle inputs and outputs for the context of VCE biology?
2) How has the pelvis changed through hominin evolution and why is this important?
3) Do T cells have specialized naive cells or are they general? (Basically, are there generalist naive T cells that differentiate into their specialties or are there naive T helper and naive cytotoxic T cells?)
4) What prevents macrophages from displaying antigens to Helper T and naive B cells? Don't both macrophages and dendritic cells express MHC II?
« Last Edit: October 28, 2018, 01:39:52 pm by C14M8S »
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Robot10

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Re: VCE Biology Question Thread
« Reply #11051 on: October 28, 2018, 01:52:27 pm »
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1) Should the link reaction be simply classed as part of the Krebs' cycle inputs and outputs for the context of VCE biology?

Yes. So pyruvate should be considered as the substrate for Krebs Cycle.

2) How has the pelvis changed through hominin evolution and why is this important?

The pelvis has become more bowl shaped and narrower. This is important to support  weight distribution and bipedalism. Can someone check this?

4) What prevents macrophages from displaying antigens to Helper T and naive B cells? Don't both macrophages and dendritic cells express MHC II?

Macophages DO present antigens to Helper T cells.

Does anyone know why MCQ 25 of the 2017 NHT Exam is D and not B?

Thanks
« Last Edit: October 28, 2018, 01:54:20 pm by Robot10 »

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Re: VCE Biology Question Thread
« Reply #11052 on: October 28, 2018, 01:54:42 pm »
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In autocrine signalling, is the signalling molecule considered external?
Thanks as always!

vox nihili

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Re: VCE Biology Question Thread
« Reply #11053 on: October 28, 2018, 01:56:51 pm »
+4
1) Should the link reaction be simply classed as part of the Krebs' cycle inputs and outputs for the context of VCE biology?
2) How has the pelvis changed through hominin evolution and why is this important?
3) Do T cells have specialized naive cells or are they general? (Basically, are there generalist naive T cells that differentiate into their specialties or are there naive T helper and naive cytotoxic T cells?)
4) What prevents macrophages from displaying antigens to Helper T and naive B cells? Don't both macrophages and dendritic cells express MHC II?

1. Yep, just presume that pyruvate starts off Krebs. Don't worry about acetyl-CoA
2. You should try to answer this first.
3. Not relevant to VCE.
4. Also not relevant to VCE, but you're quite right to ask this question. Basically it's got to do with where the cells go. Dendritic cells activate helper T-cells because they go to the lymph nodes to activate them. Macrophages do indeed present antigens to T-helper cells, but where this fits into the context of an immune reaction is beyond VCE. An important VCE point though: NO cell presents antigen to B-cells. B-cells cannot see antigen in the context of MHC molecules; they only bind to free antigen.

Does anyone know why MCQ 25 of the 2017 NHT Exam is D and not B?

Thanks

Copy the question here please

In autocrine signalling, is the signalling molecule considered external?
Thanks as always!

The signal is externalised, but I don't know what you mean by "considered external".
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Robot10

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Re: VCE Biology Question Thread
« Reply #11054 on: October 28, 2018, 02:01:21 pm »
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Does anyone know why MCQ 25 of the 2017 NHT Exam is D and not B?

Thanks