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August 07, 2020, 08:01:45 pm

Author Topic: VCE Biology Question Thread  (Read 1752315 times)  Share 

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Evolio

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Re: VCE Biology Question Thread
« Reply #11760 on: June 16, 2019, 10:09:15 am »
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Hi guys!  :)
I just had a few questions to ask.

Are pathogens recognised as foreign by the absence of self markers or by the presence of non-self markers?

Also, is it correct to say that virions are non-cellular pathogens?

Just to confirm, are antigens molecules that are recognised as foreign by the immune cells? Are antigens non-self markers?

When describing the steps of the immune response, what the main points we should include because in some sources there is more detail while in other details they don't say that a fever is caused when macrophages secrete interleukins for example?

Thank you for your help.


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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11761 on: June 16, 2019, 11:27:40 am »
+6
Hi guys!  :)
I just had a few questions to ask.

Are pathogens recognised as foreign by the absence of self markers or by the presence of non-self markers?
Presence of non self markers - antigens. However the absence of a self marker (such as MHC) can also cause an immune response against that cell.

Also, is it correct to say that virions are non-cellular pathogens?
Yep.

Just to confirm, are antigens molecules that are recognised as foreign by the immune cells? Are antigens non-self markers?
Sort of. Antigens are molceules that trigger the production of antibodies - this should mean that they're all non-self, but in the case of things like an auto-immune response, an antigen can be a self molecule.

When describing the steps of the immune response, what the main points we should include because in some sources there is more detail while in other details they don't say that a fever is caused when macrophages secrete interleukins for example?

Thank you for your help.
It depends what part of the immune response you're talking about - you can have a flick through past exam answers and see what they've considered important.

Humoral:
- Naive B cell binds to free antigen
- T helper cell binds to identical antigen presented on MHC2
- T helper cell releases cytokines that cause proliferation and differentiation of both B and Th cells.
- Memory cells stick around, B plasma cells produce heaps of antibodies complementary to the antigen.

Cell-mediated:
- Cytotoxic T cell binds to antigen presented on MHC1.
- Releases granzymes and perforins that kill the cell
- Divides and differentiates and goes around killing other cells presenting identical antigen fragments.
- Maybe mention that cytokines released from T helper cells help with the Tc cell proliferating and differentiating, but also might not need to mention that.

^They're just the rough points, you should write out the ideas properly, but that's the important bits.
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Evolio

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Re: VCE Biology Question Thread
« Reply #11762 on: June 16, 2019, 11:36:11 am »
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Thank you, PhoenixxFire!
 ;D
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GodNifty

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Re: VCE Biology Question Thread
« Reply #11763 on: June 17, 2019, 10:49:18 pm »
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- Does clonal expansion mean all progenies are the same, or all progenies have the same antigen specificity, and can be of any type (like plasma cell and memory cell)
- In humoral response, when one Helper T cell is selected and clonal expands, can they differentiate into Memory T cells or just more Helper T Cells?
- Are second line defense leukocytes involved in the cell mediated or just normal cells?
- Do Cytotoxic T cells act as death ligands or do they secrete molecules (like cytokines) as death ligands?

Thanks all

PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11764 on: June 18, 2019, 11:23:23 am »
+1
- Does clonal expansion mean all progenies are the same, or all progenies have the same antigen specificity, and can be of any type (like plasma cell and memory cell)
Same antigen specificity

- In humoral response, when one Helper T cell is selected and clonal expands, can they differentiate into Memory T cells or just more Helper T Cells?
Both. There's probably a more scientific name for each of the types, but some of the Th cells will fight the current infection, and some will be memory cells.

- Are second line defense leukocytes involved in the cell mediated or just normal cells?
Which leukocytes do you mean? (leukocyte is a very broad term and includes everything from neutrophils and basophils to B and T cells). If you're referring to phagocytes they'll eat the apoptotic fragments formed as a result of cell-mediated immunity, but that's it.

- Do Cytotoxic T cells act as death ligands or do they secrete molecules (like cytokines) as death ligands?

Thanks all
Cytotoxic T cells release perforin (a protein that can make holes in membranes), and granzymes (an enzyme that enters the cell and activates caspases, inducing apoptosis).
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Zacm

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Re: VCE Biology Question Thread
« Reply #11765 on: June 18, 2019, 06:30:55 pm »
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How can I access the 2019 unit 1 neap exam answers?

jack.cameron

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Re: VCE Biology Question Thread
« Reply #11766 on: June 19, 2019, 07:24:59 pm »
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Does anybody have any u3 aos 2 practise sacs or any online practise questions. I've done all my schools practise sacs and every other resource I've bought or have been given. cheers
« Last Edit: June 19, 2019, 07:27:48 pm by jack.cameron »

PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11767 on: June 19, 2019, 07:49:08 pm »
+1
Does anybody have any u3 aos 2 practise sacs or any online practise questions. I've done all my schools practise sacs and every other resource I've bought or have been given. cheers

There's some practice questions I wrote a couple of years ago here, but they're not really the sorts of questions you'll get on SACs, so probably not very helpful outside of checking you haven't missed any content.

From the sounds of things you've already done quite a lot of practice questions - if so, it'll probably be more useful to go back and redo the ones you didn't get full marks on, there's no point doing copious amounts of questions if they're not helping you improve your answers.
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jack.cameron

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Re: VCE Biology Question Thread
« Reply #11768 on: June 19, 2019, 07:55:06 pm »
+1
There's some practice questions I wrote a couple of years ago here, but they're not really the sorts of questions you'll get on SACs, so probably not very helpful outside of checking you haven't missed any content.

From the sounds of things you've already done quite a lot of practice questions - if so, it'll probably be more useful to go back and redo the ones you didn't get full marks on, there's no point doing copious amounts of questions if they're not helping you improve your answers.
I'm getting full marks on practically everything I do, it's more just I'm trying to expose myself to as many variations of questions so on the day I don't get confused by any questions. Thank you for the resource though

Evolio

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Re: VCE Biology Question Thread
« Reply #11769 on: June 19, 2019, 08:03:49 pm »
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Hello guys.
I just wanted someone to check my response to this question and give me any constructive feedback. It is worth 2 marks.

Describe how hydrophilic hormones, such as glucagon, stimulate a metabolic process, such as glycogenolysis, inside a cell
Response:
Hydrophilic hormones(signalling molecules) such as glucagon bind to a cell surface receptor. Then second messengers are produced, causing a chain of relay molecules to be produced. The signal is amplified until it reaches the nucleus of the cell, where the chemical message is received. Then genes can be expressed to allow for a metabolic process, such as glycogenolysis to occur inside the cell.

Are second messengers produced, activated or stimulated?



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FrankieDens

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Re: VCE Biology Question Thread
« Reply #11770 on: June 19, 2019, 08:08:43 pm »
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Hey everyone!

If any of you have the time can you please answer some of my 'confusions'? (hehe Kansas vs Arkansas):

  • Where are complement proteins produced and how is it activated?
  • What is the purpose of complement proteins?
  • What are the steps of monoclonal antibody production?
  • Does anyone have a good definition for herd immunity?
  • Why are booster shots needed?
  • (Exam 1, 2013) VCAA stated that booster shots are needed to produce more memory cells because they are short-lived... but I thought memory cells are produced for long-term memory?
Thank you!  :D
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DBA-144

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Re: VCE Biology Question Thread
« Reply #11771 on: June 19, 2019, 08:28:17 pm »
+2
Hey everyone!

If any of you have the time can you please answer some of my 'confusions'? (hehe Kansas vs Arkansas):

  • Where are complement proteins produced and how is it activated?
  • What is the purpose of complement proteins?
  • What are the steps of monoclonal antibody production?
  • Does anyone have a good definition for herd immunity?
  • Why are booster shots needed?
  • (Exam 1, 2013) VCAA stated that booster shots are needed to produce more memory cells because they are short-lived... but I thought memory cells are produced for long-term memory?
Thank you!  :D

All proteins are produced at a ribosome, complement proteins produced in the liver specifically. Purpose is just to adhere to any non self antigen (they're non specific) and will lyse bacterial cells, opsonise antigens/pathogens and are involved in the clearance of antigen antibody complexes.

Imo steps of the production of monoclonal antibodies is not needed for the course, only the uses.
Hello guys.
I just wanted someone to check my response to this question and give me any constructive feedback. It is worth 2 marks.

Describe how hydrophilic hormones, such as glucagon, stimulate a metabolic process, such as glycogenolysis, inside a cell
Response:
Hydrophilic hormones(signalling molecules) such as glucagon bind to a cell surface receptor. Then second messengers are produced, causing a chain of relay molecules to be produced. The signal is amplified until it reaches the nucleus of the cell, where the chemical message is received. Then genes can be expressed to allow for a metabolic process, such as glycogenolysis to occur inside the cell.

Are second messengers produced, activated or stimulated?

Second messengers are activated. Look at a diagram of signal transduction and note that the reception of the ligand by its specific protein receptor on the taget cell's surface induces a conformational change in the receptor. This shape change is what leads to the activation of second messengers. THese are present in inactive forms in the cell. I suspect there will be cases were these are produced, but this isn't really required info.

There might be cases where a second messenger activates a molecule which then splits into 2 parts, one of which is used later in the pathway, for example. Again, this is not required knowledge.

Your response is ok. Perhaps you might like to say that the cell responds by >>>sythesising proteins that allow... to occur<<<. This is not essential, from what I have seen, but it might be something you want to include.

jack.cameron

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Re: VCE Biology Question Thread
« Reply #11772 on: June 20, 2019, 08:05:35 pm »
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does anyone have a definition for natural immunity only (not tagged on with active or passive) that doesn't involve the word natural or naturally. cheers xx

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Re: VCE Biology Question Thread
« Reply #11773 on: June 20, 2019, 08:17:33 pm »
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perhaps someone's already answered this but there are so many pages on this forum so im just gonna ask anyway haha:

"How do blood glucose levels regulate when the levels are too high/low?"

does anyone have a definition for natural immunity only (not tagged on with active or passive) that doesn't involve the word natural or naturally. cheers xx

when a human is exposed to a live pathogen and develops that disease and if they become immune afterwards (primary immune response), this would classify as natural immunity

very simple definition: occurs when exposed to live pathogen, develops disease, and becomes immune as a result of the primary immune response

i honestly dont know if this helped and i had to google this to make sure i was right https://courses.lumenlearning.com/boundless-microbiology/chapter/classifying-immunities/

Mod edit: I've merged your posts. If you need to add new information, rathe than posting again right after, please click the 'modify' button, which you can find next to the quote button :)
« Last Edit: June 20, 2019, 08:28:53 pm by Calebark »
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Re: VCE Biology Question Thread
« Reply #11774 on: June 20, 2019, 08:28:04 pm »
+3
Hello! As you probably know it's a form of negative feedback where the body is working to maintain homeostasis by reversing the direction of the change.

For high blood glucose:
High blood glucose levels will be detected by receptors in the pancreas.
They will release insulin which will target the liver.
Consequently, more glucose in the blood will be converted to it's stored form, glycogen.
Blood glucose levels will return to normal and homeostasis is maintained.

For low blood glucose:
Low blood glucose levels will be detected by receptors in the pancreas.
They will release glucagon which will target the liver.
This stimulates the conversion of more glycogen to glucose.
The blood glucose levels return to normal.

Hope this helps!!
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