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March 29, 2024, 11:24:02 am

Author Topic: VCE Biology Question Thread  (Read 3571114 times)  Share 

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asdfdsa

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Re: VCE Biology Question Thread
« Reply #9150 on: May 06, 2017, 07:38:25 pm »
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Well there isn't a lot to know or say about auxin. General knowledge of the cellular responses prompted by auxin is essential along with it's role in apical dominance. It's also useful to know about Indole Acetic Acid (IAA) as a common example of an auxin, as well as the areas on plants which produce auxin and how it travels through the plant. Of course the most important part of auxin is it's role in tropisms, more specifically phototropism and geotropism.
thanks for the explanation!

Ahmad_A_1999

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Re: VCE Biology Question Thread
« Reply #9151 on: May 07, 2017, 11:30:00 am »
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Hey guys,

Could someone please explain the term 'cascade' to me in terms of signal transduction of polar/non-polar signalling molecules, and where does it fit in each event.

Thanks in advance
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TheAspiringDoc

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Re: VCE Biology Question Thread
« Reply #9152 on: May 07, 2017, 12:10:24 pm »
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Hey guys,

Could someone please explain the term 'cascade' to me in terms of signal transduction of polar/non-polar signalling molecules, and where does it fit in each event.

Thanks in advance
A signal cascade is the sequence of biochemical reactions in which each reaction causes the next reaction to be possible. It's like a sequence of dominoes tipping each other over. In the transduction of polar ligands, the ligand (usually a hormone I think?) is unable to diffuse across the phospholipid bilayer so it binds to a membrane receptor. The receptor's shape (configuration) then changes - which in turn changes the shape of - and hence activates - a second messenger in the cell's cytosol. This activated second messenger then activates another second messenger which activates another second messenger which ... .   this is what we refer to as a signal transduction cascade. For a non-polar hormone, it diffuses across the phospholipid bilayer and binds to an intracellular receptor - forming a hormone-receptor complex. This complex may then act as a transcription factor - controlling the expression of particular genes. To my knowledge, no cascade occurs in this scenario.

That's only my understanding of it though, and I'd really appreciate if someone could read over it and confirm whether what I'm saying is actually correct!

cookiedream

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Re: VCE Biology Question Thread
« Reply #9153 on: May 07, 2017, 02:38:49 pm »
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A signal cascade is the sequence of biochemical reactions in which each reaction causes the next reaction to be possible. It's like a sequence of dominoes tipping each other over. In the transduction of polar ligands, the ligand (usually a hormone I think?) is unable to diffuse across the phospholipid bilayer so it binds to a membrane receptor. The receptor's shape (configuration) then changes - which in turn changes the shape of - and hence activates - a second messenger in the cell's cytosol. This activated second messenger then activates another second messenger which activates another second messenger which ... .   this is what we refer to as a signal transduction cascade. For a non-polar hormone, it diffuses across the phospholipid bilayer and binds to an intracellular receptor - forming a hormone-receptor complex. This complex may then act as a transcription factor - controlling the expression of particular genes. To my knowledge, no cascade occurs in this scenario.

That's only my understanding of it though, and I'd really appreciate if someone could read over it and confirm whether what I'm saying is actually correct!

Couldn't have explained it any better. That's pretty much exactly what happens.
What's the definition of a transcription factor? ???
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vcestressed

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Re: VCE Biology Question Thread
« Reply #9154 on: May 07, 2017, 02:52:02 pm »
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Couldn't have explained it any better. That's pretty much exactly what happens.
What's the definition of a transcription factor? ???
Wrong person but - transcription factor is anything that affects or controls the gene expression at the transcription stage by binding to DNA regions or to the RNA polymerase so that it can start or stop the expression of that particular gene. So in the lac operon, the transcription factor would be the repressor :)

TheAspiringDoc

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Re: VCE Biology Question Thread
« Reply #9155 on: May 07, 2017, 03:21:04 pm »
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Wrong person but - transcription factor is anything that affects or controls the gene expression at the transcription stage by binding to DNA regions or to the RNA polymerase so that it can start or stop the expression of that particular gene. So in the lac operon, the transcription factor would be the repressor :)
I thought the term "transcription factor" only applied to eukaryotes and therefore not to the lac operon?

vcestressed

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Re: VCE Biology Question Thread
« Reply #9156 on: May 07, 2017, 03:36:02 pm »
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I thought the term "transcription factor" only applied to eukaryotes and therefore not to the lac operon?
I'm pretty sure that isn't the case because I just checked my book and it says that the 'lac repressor' is a transcription factor but I could be wrong. . .
I have the heinemann bio book btw 

masonjar

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Re: VCE Biology Question Thread
« Reply #9157 on: May 07, 2017, 04:07:14 pm »
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Hey! I'm not sure this is the right thread for this- so I'm sorry, if it D:

But, I just had a question about biology sacs. I have trouble with being able to use the key knowledge we learn in class to practicaly questions- and generally just applying knowledge into questions. Do you have any tips or something that could help me out? I feel a bit lost, and am not sure exactly how to improve it, aha.

Thanks :)

Quantum44

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Re: VCE Biology Question Thread
« Reply #9158 on: May 07, 2017, 04:42:30 pm »
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Hey! I'm not sure this is the right thread for this- so I'm sorry, if it D:

But, I just had a question about biology sacs. I have trouble with being able to use the key knowledge we learn in class to practicaly questions- and generally just applying knowledge into questions. Do you have any tips or something that could help me out? I feel a bit lost, and am not sure exactly how to improve it, aha.

Thanks :)

Well biology, as you have found out, is not just about knowledge but also expression; in fact many people struggle with expression as your answers have to be clear and concise to be awarded marks. It is fairly difficult to actually improve as it will happen over the course of the year. That being said, you can definitely speed up your development of 'biological' expression by doing practice questions and getting your teacher to give you feedback and reading examiners reports/model answers. An good example of this is to choose a few questions you think will be on the SAC (from past exams/checkpoints/other sources) and then spend some time writing what you perceive to be good responses to them. Then you can give them to your teacher to mark and get feedback on how you apply knowledge to questions before each SAC.

The best advice I can give for expression is to always think of key words you should include in your answer to get full marks, and to be aware of the type of question it is. For example if the question is about comparing two things, you need to use the words 'compared to' or 'whereas' to fully explain the differences between the two things.
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simrat99

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Re: VCE Biology Question Thread
« Reply #9159 on: May 08, 2017, 08:33:28 pm »
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Hey guys, I was wondering how much do we have to know about neurons in this year's course?
Thanks :)

Gogo14

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Re: VCE Biology Question Thread
« Reply #9160 on: May 08, 2017, 10:12:43 pm »
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Hey guys, I was wondering how much do we have to know about neurons in this year's course?
Thanks :)
General structure of a neuron. How they transmit signals across the synaptic celft(important). Action potention and how it works. Reflex arc. Role of neurons and hte 3 types of neurons(motor, interneuron, sensory).
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vox nihili

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Re: VCE Biology Question Thread
« Reply #9161 on: May 09, 2017, 02:50:22 pm »
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General structure of a neuron. How they transmit signals across the synaptic celft(important). Action potention and how it works. Reflex arc. Role of neurons and hte 3 types of neurons(motor, interneuron, sensory).

Also really important to understand the role of myelin in transmission, as MS has been introduced to the course as something you need to know about
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Ahmad_A_1999

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Re: VCE Biology Question Thread
« Reply #9162 on: May 09, 2017, 11:02:23 pm »
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General structure of a neuron. How they transmit signals across the synaptic celft(important). Action potention and how it works. Reflex arc. Role of neurons and hte 3 types of neurons(motor, interneuron, sensory).

Where in the study design does it say that  :'( all I'm getting is the 'source' and 'mode of transmission' of neurotransmitters, our biology teachers said there is less emphasis on the action potential stuff  :-\  Please clarify
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Quantum44

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Re: VCE Biology Question Thread
« Reply #9163 on: May 10, 2017, 07:39:36 am »
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Where in the study design does it say that  :'( all I'm getting is the 'source' and 'mode of transmission' of neurotransmitters, our biology teachers said there is less emphasis on the action potential stuff  :-\  Please clarify

There is very much less of a focus on action potential however it still might come up and is worth knowing. VCAA really love neurotransmission though, so if neurons ever come up, it will be about how the action potential is transferred across the synapse. The reflex arc was something they liked to test in previous study designs, so you will see it a lot in last exams, but is very unlikely to come up in this study design.

As Vox nihili said, MS is explicitly mentioned as an example of an autoimmune disease so it is also worth investigating the myelin sheath in detail.
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simrat99

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Re: VCE Biology Question Thread
« Reply #9164 on: May 13, 2017, 10:14:09 am »
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Hi, are we expected to know about negative or positive feedback systems? Thanks  :)