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Author Topic: VCE Biology Question Thread  (Read 3570631 times)  Share 

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Erutepa

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Re: VCE Biology Question Thread
« Reply #11355 on: November 01, 2018, 03:09:23 pm »
+1
1) In outcome two, part of the last study design point is "the use of scientific knowledge to identify the pathogen, and the types of
treatments".
I always took this to mean that given a scenario where certain characteristics of a pathogen are stated (i.e. non-cellular, contains nucleic acid) from which you have to explain what the pathogen is. However, In the 2017 sample exam, it asks to "describe a modern method that is used to quickly identify a pathogen" (question 10e).
Should we really know pathogen identification methods?
if so, which ones would be best for our course? (I imagine there would be endless numbers of different tests you could explain)

2) For question 10c of the same 2017 practice exam asking to "identify two pieces of evidence that support the hypothesis that the virus was not being carried by mosquitos" what evidence would you state? (i assume the evidence would have to be observations from the question stem)

Thanks
« Last Edit: November 01, 2018, 03:22:26 pm by Erutepa »
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AISHAB

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Re: VCE Biology Question Thread
« Reply #11356 on: November 01, 2018, 03:25:51 pm »
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I think Douchy talks about G proteins? You don’t need to know about that.

Just need to know the three steps (reception, transduction, response) and that different transduction pathways can result in different reaponses to the same signalling molecule

Thanks! Could someone please explain how the intrinsic apoptosis pathway works?

Erutepa

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Re: VCE Biology Question Thread
« Reply #11357 on: November 01, 2018, 03:29:22 pm »
+1
Thanks! Could someone please explain how the intrinsic apoptosis pathway works?
The intrinsic pathway is mediated by the mitochondria. When the cell recognizes stress, irreparable damage, aberrant activity (or a bunch of other things), the mitochondria will release cytochrome C. This will activate caspases which (in a signal cascade) activate other caspases as well as cleave cellular elements like the cytoskeleton. This causes cell breakdown, blebbing and the eventual formation of apoptotic bodies.
« Last Edit: November 01, 2018, 03:31:45 pm by Erutepa »
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Re: VCE Biology Question Thread
« Reply #11358 on: November 01, 2018, 03:31:01 pm »
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In transcription, does the DNA unwind first or does RNA polymerase bind first, causing the DNA to unwind?

darkz

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Re: VCE Biology Question Thread
« Reply #11359 on: November 01, 2018, 03:33:39 pm »
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Thanks! Could someone please explain how the intrinsic apoptosis pathway works?

- Cytochrome C is released by the mitochondria, stimulating a cascade of events whereby caspases are activated. The caspases cleave protein and nucleic acid. Cytoskeleton is dismantled and the rest is the same as the extrinsic method

1) In outcome two, part of the last study design point is "the use of scientific knowledge to identify the pathogen, and the types of
treatments".
I always took this to mean that given a scenario where certain characteristics of a pathogen are stated (i.e. non-cellular, contains nucleic acid) from which you have to explain what the pathogen is. However, In the 2017 sample exam, it asks to "describe a modern method that is used to quickly identify a pathogen" (question 10e).
Should we really know pathogen identification methods?
if so, which ones would be best for our course? (I imagine there would be endless numbers of different tests you could explain)

2) For question 10c of the same 2017 practice exam asking to "identify two pieces of evidence that support the hypothesis that the virus was not being carried by mosquitos" what evidence would you state? (i assume the evidence would have to be observations from the question stem)

Thanks

The easiest methods to write about would be using PCR, electron microscopy or culturing the pathogen to identify what it is

You can say that mosquitos have an equal chance of infecting/biting men/women, therefore the differences highlighted in the text about these proportions indicates it would be unlikely to be through mosquitos. And because the text says that those who washed the body with their bare hands developed the disease, it could be hypothesised that it was transmitted instead via direct contact

In transcription, does the DNA unwind first or does RNA polymerase bind first, causing the DNA to unwind?

I believe the DNA unwinds first to allow for the binding of RNA polymerase to the promoter
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Erutepa

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Re: VCE Biology Question Thread
« Reply #11360 on: November 01, 2018, 03:37:04 pm »
+2
In transcription, does the DNA unwind first or does RNA polymerase bind first, causing the DNA to unwind?
DNA does unwind first (this is done by enzyme helicase) allowing RNA binding to the promoter.

The easiest methods to write about would be using PCR, electron microscopy or culturing the pathogen to identify what it is

You can say that mosquitos have an equal chance of infecting/biting men/women, therefore the differences highlighted in the text about these proportions indicates it would be unlikely to be through mosquitos. And because the text says that those who washed the body with their bare hands developed the disease, it could be hypothesised that it was transmitted instead via direct contact

Thanks. Very Helpful (as always)
« Last Edit: November 01, 2018, 03:38:40 pm by Erutepa »
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Re: VCE Biology Question Thread
« Reply #11361 on: November 01, 2018, 03:39:00 pm »
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http://ib.bioninja.com.au/standard-level/topic-2-molecular-biology/27-dna-replication-transcri/transcription.html#previous-photo

According to this website, RNA polymerase separates the DNA strands. In this context, is separating the same as unwinding?

vox nihili

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Re: VCE Biology Question Thread
« Reply #11362 on: November 01, 2018, 03:45:24 pm »
+3
http://ib.bioninja.com.au/standard-level/topic-2-molecular-biology/27-dna-replication-transcri/transcription.html#previous-photo

According to this website, RNA polymerase separates the DNA strands. In this context, is separating the same as unwinding?

Yes.

(to those who think it's helicase that does this, don't worry, well beyond VCE. Suffice to say that RNA pol actually has a helicase domain attached to it).
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Re: VCE Biology Question Thread
« Reply #11363 on: November 01, 2018, 03:54:45 pm »
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I was going through the Biology Study design and came across this dotpoint

- the nature of evidence that supports or refutes a hypothesis, model or theory

Could someone please explain what this means.

Could someone also give me a definition for fossil record? What would we need to include

This is what Bio ninja said The totality of fossils, both discovered and undiscovered but google said
Britannica said the history of life as documented by fossils, the remains or imprints of the organisms from earlier geological periods preserved in sedimentary rock

Thanks

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Re: VCE Biology Question Thread
« Reply #11364 on: November 01, 2018, 03:57:18 pm »
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Can someone plz summarise the cell-mediated response? Is this correct: APC's present antigens to helper t-cells, helper t-cells release cytokines, stimulate the clonal expansion of t-cells. More helper t-cells, t-memory cells and cytotoxic t-cells specific to the antigen are produced?

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Re: VCE Biology Question Thread
« Reply #11365 on: November 01, 2018, 04:01:15 pm »
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Can someone plz summarise the cell-mediated response? Is this correct: APC's present antigens to helper t-cells, helper t-cells release cytokines, stimulate the clonal expansion of t-cells. More helper t-cells, t-memory cells and cytotoxic t-cells specific to the antigen are produced?

I think you might need to add that the cytotoxic T-cells induce apoptosis in the specific target cells.
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11366 on: November 01, 2018, 04:04:02 pm »
+3
I was going through the Biology Study design and came across this dotpoint

- the nature of evidence that supports or refutes a hypothesis, model or theory

Could someone please explain what this means.

Could someone also give me a definition for fossil record? What would we need to include

This is what Bio ninja said The totality of fossils, both discovered and undiscovered but google said
Britannica said the history of life as documented by fossils, the remains or imprints of the organisms from earlier geological periods preserved in sedimentary rock

Thanks
Pretty sure that study design dot point is just saying that if the results show what you predicted they'd show then that supports your hypothesis.

The fossil record is just fossils of species that have been preserved. Both of those definitions say pretty much the same thing, the Britannica one is just in more detail. Really doubt you'll be asked to define it.

Can someone plz summarise the cell-mediated response? Is this correct: APC's present antigens to helper t-cells, helper t-cells release cytokines, stimulate the clonal expansion of t-cells. More helper t-cells, t-memory cells and cytotoxic t-cells specific to the antigen are produced?
You don't need to talk about T helper cells that much.
Here's what I had in my notes about it:
-Naive Tc cells are always travelling throughout the body, attempting to bind to peptide fragments presented on MHC1 markers.
-When they find one that they can bind to, the Tc cell is ‘selected’
-The Tc cell will release granzymes (including perforin) which cause the cell to undergo apoptosis.
-The Tc cell continues to travel throughout the body and kill cells presenting the same peptide, but it will not divide or differentiate until cytokines are present.
-When cytokines have been released from the Th cells (this could happen before or after the Tc cell is selected), the Tc cell will divide (proliferate) and differentiate into Tc memory cells and Tc effector cells.
-The Tc memory cells will remain in the body to fight off subsequent infection by the same pathogen.
-The effector Tc cells will travel throughout the body, inducing apoptosis in cells presenting the same peptide fragment as the original cell.
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Re: VCE Biology Question Thread
« Reply #11367 on: November 01, 2018, 04:06:28 pm »
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could someone please give me some examples of biological, social and ethical implications

also what is the best way to use reading time?

Could you specify what scenario you'd like implications for? If it's for GMOs, then biological could mean adversely affecting the health of the organism you're modifying; social could mean solving hunger crises as a positive implication, or maybe only the wealthy could afford to use such modifications; and ethical implications could involve infringing on animal rights, or how a company could/should patent the use of a gene.

As for reading time, one of my teachers recommends that you read over multiple choice, then start doing short-answer questions first, because:
a. If you're short on time near the end of the exam, it's a lot easier to guess a bunch of multiple choice questions than it is to fill out a page of short-answer questions
b. Since there are a lot of multiple choice questions, there's a chance that you could get a question stem in MC that's related to something in SA.

Hope this helps!
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11368 on: November 01, 2018, 04:11:01 pm »
+3
could someone please give me some examples of biological, social and ethical implications

also what is the best way to use reading time?
Social and ethical issues:
Here are some social and ethical implications of DNA profiling (+ pros, - cons)
+ regular health monitoring of individuals can be implemented, and preventative action can be taken on individuals with genetic disorders/diseases.
+ couples can plan their pregnancy, and make preparations based on the results of DNA profiling/screening for their child
+ a negative result on screening/profiling in relation to genetic diseases can often reduce emotional stress
- a positive result of a genetic disease may induce stress, and can be an emotional burden
- DNA profiling and genetic screening can hinder with one's privacy
- DNA profiling and genetic screening can often be inconclusive, and data can be difficult to interpret

Social and ethical implications of genetic cloning (and also genetic engineering technology which produces GMOs)
+ producing enhanced crops, and organisms, which translates to technological advancement
+ higher quality of life
+ alleviate poverty (higher yielding crops)
+ reduce the detrimental effects of diseases (check out golden rice, transgenic rice with beta carotene which turns into vitamin A, to aid with vitamin A deficiencies within poorer nations)
- genetically modified organisms or cloned genes may affect ecosystems as gene flow might occur between natural and modified organisms (some genes may result in a selective advantage, which affects the allele frequencies of populations)
- companies might claim segments of genes as intellectual property (unethical), and charge high prices for any research/development involving the specific gene.
- GMOs can affect the production of traditional food, and might or might not be adequate substitutes for these traditional food items in providing the required nutrition.
- thorough, rigorous and independent testing of GMOs are required to ensure that the segments of cloned genes do not affect the quantity of production, and gene flow between modified and natural populations that can lead to devastating consequences.

Biological issues are generally things related to reducing the gene pool and the effects of that on evolution/natural selection/likelihood of extinction/etc.

For the reading time I read the short answer questions because it gives you a bit of an idea of what's ahead - you know whether you're going to turn the page and have 1 question or 6 questions - and then I start from the multi choice during writing time.
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Re: VCE Biology Question Thread
« Reply #11369 on: November 01, 2018, 04:25:07 pm »
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What are the inputs and outputs of kreb cycle and ETC?