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July 10, 2020, 07:22:54 pm

Author Topic: VCE Biology Question Thread  (Read 1730811 times)  Share 

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whys

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Re: VCE Biology Question Thread
« Reply #12510 on: May 16, 2020, 10:16:04 am »
+5
When looking at antibody count in the blood after vaccinations, why doesn't the count drop to zero?

Also for question 8 c. exam 1 2010, why is the antibody count in the baby above zero before the initial vaccine? (I deciphered this is because antibodies, through natural passive immunity, has reached the baby from the mother. But if the mother was only infected with measles as a child, why did she still have antibodies specific to measles after so many years?)

I am assuming that in an ideal situation, the antibody count of the baby would be above zero for the reasons that you have outlined. Although the mother only had measles as a child, you probably need to assume that her immunological memory has been intact for a long time, although this probably isn't true in real life as immunity can diminish over time in many cases.

As the baby was exposed to two vaccinations, its immunological memory (prevalence of antibodies specific to measles and memory cells) won't fade anytime soon, although it is possible it could technically drop to zero in the far future if it is not exposed to measles again.

^This is my understanding of the immune system, feel free to correct me if I'm wrong :)
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vox nihili

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Re: VCE Biology Question Thread
« Reply #12511 on: May 17, 2020, 12:13:10 am »
+6
When looking at antibody count in the blood after vaccinations, why doesn't the count drop to zero?

Also for question 8 c. exam 1 2010, why is the antibody count in the baby above zero before the initial vaccine? (I deciphered this is because antibodies, through natural passive immunity, has reached the baby from the mother. But if the mother was only infected with measles as a child, why did she still have antibodies specific to measles after so many years?)

In Australia, vaccination against measles is a two-dose schedule. The first dose is generally given at age 12 months
and the second dose at 4 years.
c. On the grid below, graph the level of measles antibodies you would expect in a vaccinated child.
The child’s mother is known to have had measles as a child.


These are both really excellent questions. whys has given you an answer that is pretty close to the money, but I will clear up a couple of things.

whys is absolutely right in saying that immunity will theoretically drop to zero after some time. In the graph you've provided, it is dropping towards zero, but on both occasions a vaccine prevents it from doing so. This may help to explain why we vaccinate at these ages!
Theoretically, at the end of each year you are left with fewer B-cells specific to measles, so your immunity does wane over time. This is particularly the case for vaccine-induced immunity, which is far less robust than immunity that comes from having a disease.

Your second point is correct. The baby has immunity initially as it has acquired it from the mother. The antibodies cross the placenta and are with the baby from birth. Over time, these antibodies break down, so the baby gets more from the mother via breast milk. You suggested that the mother might not have immunity to measles, because it has been a long time since she has had the disease. whys was also unsure about whether the mother would actually have immunity in real life. The simple answer is that yes, she would! As I alluded to earlier, immunity acquired from getting a disease is a lot more robust (i.e. it lasts longer). So even though the mother had the disease as a child, you would expect that immunity to be with her until she dies.
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WhatisaMeMe

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Re: VCE Biology Question Thread
« Reply #12512 on: May 17, 2020, 04:11:10 pm »
0
Hi just a quick question:
Is a signal-protein complex formed inside the cell from hydrophobic signalling molecules considered a secondary messenger by its own? Thanks
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ErnieTheBirdi

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Re: VCE Biology Question Thread
« Reply #12513 on: May 19, 2020, 09:53:42 am »
+1
Hey everyone! I have an upcoming AOS2 SAC2 for Unit3 on immunity and all the signalling stuff. I still don't really understand it all, for example, naive and regular cells? Lymphatic system and MHC proteins? I was just wondering i someone would be able to explain those things to me? and if possible give me a guideline/checklist on what to look out for/study more of for the SAC (I know it's on the study design).

Sine

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Re: VCE Biology Question Thread
« Reply #12514 on: May 19, 2020, 02:00:15 pm »
+6
Hey everyone! I have an upcoming AOS2 SAC2 for Unit3 on immunity and all the signalling stuff. I still don't really understand it all, for example, naive and regular cells? Lymphatic system and MHC proteins? I was just wondering i someone would be able to explain those things to me? and if possible give me a guideline/checklist on what to look out for/study more of for the SAC (I know it's on the study design).
The content can sometimes differ between schools depending on how fast they cover the content and when they cover it. However, the general things I think it would be good to learn would be.
- What is an antigen?
- What is a self-antigen, non-self antigens?
- How do allergens elicit an immune response?
- What are some chemical and physical barriers? (i.e the 1st line of defence).
- Types of cells involved in the innate immune system + the complement system
- lymphatic system
- lymphocytes (B and T cells)
- How are these lymphocytes activated, what are they activated by, what is there functions etc
- Distinguish between humoral and cell-mediated immunity
- What are the two main T cells and their functions
- How to acquire immunity (passive/active), have examples
- DIffer between natural/artificial immunity
-Vaccinations/herd immunity
-Clinical use of mAb

Definitely not everything but going through this should be a good revision of an overview of the immune system in terms of what VCAA want you to know.


thatdumbstudent

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Re: VCE Biology Question Thread
« Reply #12515 on: May 22, 2020, 08:52:09 pm »
0
list five examples of molecules that may be ligands for PRRs?

i am quite confused about this. also, are PRRs receptors for PAMPs? in that cause, does that mean they bind with each other?

darkz

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Re: VCE Biology Question Thread
« Reply #12516 on: May 22, 2020, 09:39:49 pm »
+2
list five examples of molecules that may be ligands for PRRs?

i am quite confused about this. also, are PRRs receptors for PAMPs? in that cause, does that mean they bind with each other?

As a disclaimer for everyone else, in terms of VCE Biology, you won't be required to know about PRRs or PAMPs (although I do know that some schools teach and incorporate this stuff into SACs). For your question:

Yes, PRRs are receptors used by immune cells to recognise PAMPs. In terms of examples, I don't know what depth you're after, however, they'd just be examples of distinct features of pathogens e.g. flagella, lipopolysaccharides (components of bacterial cell walls), and dsRNA.
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Snow Leopard

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Re: VCE Biology Question Thread
« Reply #12517 on: May 23, 2020, 11:17:05 pm »
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Hi Snow Leopard,

I'm pretty sure mental illnesses/disorders such as anxiety and addiction would be a negative feedback loop rather than a positive feedback loop as both are triggered by three overlapping events: the trigger or environmental cue, the mental reactivity and physical reactivity. Usually speaking and from personal experience, I find that my anxiety "loop" in a more physical/literal form reduces the change of my mindset, which thus when I studied this topic in biology, enabled me to understand that negative feedback reduces change whereas positive feedback amplified change (which will result in more of a certain product).

Hopefully, that helps :)

Have a great week and kind regards,

Darcy Dillon.
Hey Darcy, thanks for the explanation. I'm still a little confused, with a positive feedback loop aren't you re-enforcing the same behaviour (e.g: you feel anxious, but when the loop gets to the outcome, don't you feel even more anxious) and with a negative feedback loop if you felt anxious then wouldn't the outcome be that you've become less anxious?
(sorry if this makes no sense...maybe I'm just confusing myself)
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ABB0005

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Re: VCE Biology Question Thread
« Reply #12518 on: May 24, 2020, 07:33:45 pm »
0
Does anyone have a list or know of all the relevant questions from VCAA exams 2002-2016?

Thank you

vox nihili

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Re: VCE Biology Question Thread
« Reply #12519 on: May 24, 2020, 08:13:28 pm »
0
Hey Darcy, thanks for the explanation. I'm still a little confused, with a positive feedback loop aren't you re-enforcing the same behaviour (e.g: you feel anxious, but when the loop gets to the outcome, don't you feel even more anxious) and with a negative feedback loop if you felt anxious then wouldn't the outcome be that you've become less anxious?
(sorry if this makes no sense...maybe I'm just confusing myself)

Straying a little bit away from VCE Biology on this topic, but yes the way you've described feedback is correct.
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coldairballoon

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Re: VCE Biology Question Thread
« Reply #12520 on: May 24, 2020, 11:45:58 pm »
0
Does anyone have a list or know of all the relevant questions from VCAA exams 2002-2016?

Thank you

I don't have the book anymore but I know connect education has a whole table of the questions that are no longer relevant to the study design at the back of their notes. Checkpoints have probably left out the irrelevant questions in their book too.
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Sine

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Re: VCE Biology Question Thread
« Reply #12521 on: May 25, 2020, 02:33:29 pm »
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Does anyone have a list or know of all the relevant questions from VCAA exams 2002-2016?

Thank you
I know from the early years stuff like water balance is no longer relevant and hasn't been required for a long time. You also don't need to know stuff about specific plant hormones which were popular questions in the late 00s. However, a  lot of study design largely remains the same.

Generally, if you know the study design well enough you should be able to discern if a question is still relevant or not.

Bsaini

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Re: VCE Biology Question Thread
« Reply #12522 on: May 28, 2020, 09:36:31 pm »
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Hey,
Need help with a question

What fluid is closest to the homeostatic norm of a person and why?

a. water  b.Naci  c. gatorade

thanks in advance

darkz

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Re: VCE Biology Question Thread
« Reply #12523 on: May 29, 2020, 12:10:06 am »
+1
Hey,
Need help with a question
What fluid is closest to the homeostatic norm of a person and why?
a. water  b.Naci  c. gatorade
thanks in advance

Well I'd assume that the homeostatic norm is simply asking which of the following is isotonic i.e. similar concentration of solutes to blood. Pure water is hypotonic and would cause haemolysis. Pure NaCl would be hypertonic, leading to creation. That leaves gatorade which supposedly has a good concentration of solutes to be isotonic.
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Re: VCE Biology Question Thread
« Reply #12524 on: May 31, 2020, 10:03:43 pm »
0
Hey,
My cellular signalling SAC (1hr SAC) is in 5 days and I was wondering if you could tell me what I should do that will prepare me best.
(eg. what are the main points I should remember? are there any specific words I should use in my answers? etc.)
I also don't feel incredibly confident so any suggestions on how i can consolidate my knowledge would be great!