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March 29, 2024, 09:36:05 pm

Author Topic: VCE Biology Question Thread  (Read 3571604 times)  Share 

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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11265 on: October 31, 2018, 10:18:39 pm »
+2
Few questions

1. Do we need to know which elements macromolecules are composed of?

2. Do we need to know the bonds in each protein structure?

3. Do we need to know the stimulus response model?

Thanks guys :) :)
1. You definitely need to know DNA/RNA and amino acids (not the R group). Probably need to know carbohydrates (just the C6H12O6 thing). Don't think you need to know about lipids.

2. Yes (assuming you mean in each level)

3. Only in terms of signal transduction
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hoddemi

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Re: VCE Biology Question Thread
« Reply #11266 on: October 31, 2018, 10:22:19 pm »
0
how does a combination of selection pressures and restricted gene flow result in a new species?
thank you!

PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11267 on: October 31, 2018, 10:25:01 pm »
+1
how does a combination of selection pressures and restricted gene flow result in a new species?
thank you!
Selection pressures result in some alleles being favoured. This results in changes between generations. Restricted gene flow means that the population is not interbreeding with other populations.

So each generation, the populations of a species change a bit due to the differing selection pressures on them. The populations do not interbreed which means they are changing independently of each other (generally under different selection pressures). Eventually the populations are different enough that they are considered different species.
« Last Edit: October 31, 2018, 10:26:47 pm by PhoenixxFire »
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011116

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Re: VCE Biology Question Thread
« Reply #11268 on: October 31, 2018, 10:27:24 pm »
0
can someone please explain to me, the malfunctions in apoptosis that result in deviant cell behaviour leading to disease including cancer and also the intrinsic and extrinsic pathway?

Thank you

PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11269 on: October 31, 2018, 10:30:17 pm »
+3
can someone please explain to me, the malfunctions in apoptosis that result in deviant cell behaviour leading to disease including cancer and also the intrinsic and extrinsic pathway?

Thank you
I'm just going to copy it from my notes given I don't know how much you already know about them. Let me know if you have questions about any of this.

Malfunctions in apoptosis
Cancer is caused by a damaged cell not undergoing apoptosis. These cells divide rapidly, creating large lumps called tumours. There are many reasons why apoptosis fails to occur.
Overactive apoptosis: Leads to diseases such as Huntington’s, Alzheimer’s, type 1 diabetes
Underactive apoptosis: Leads to diseases such as cancer.

Apoptosis
Triggers:
-Cellular injury
-DNA damage
-Viral infection
-Old age
-Cell no longer needed

Mitochondrial (intrinsic) pathway:
A signal causes the mitochondria to release cytochrome C (a protein usually involved in the electron transport chain). Cytochrome C activates caspases in the cell.
When mitochondria are damaged they release signals called cytochromes. They act as signalling molecules for intracellular receptors that initiate apoptosis.

Death receptor (extrinsic) pathway:
Initiated by a signalling molecule binding to a death receptor, which causes the activation of enzymes called caspases.

Apoptosis:
Caspases are activated by either of the apoptotic pathways. Caspases are enzymes that cleave protein molecules, breaking down the cytoskeleton of the cell, as well as other proteins in the cytoplasm and nucleus. The caspases activate other enzymes called DNAses, which cut nuclear DNA. Blebs form on the surface of the cell, and the cell fragments into a group of vesicles. The contents of the cell never enter their environment, and are always contained within a phospholipid bilayer. The vesicles (or ‘blebs’ or ‘apoptotic bodies’) are engulfed by phagocytes (e.g. macrophages), and their contents are recycled.
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Erutepa

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Re: VCE Biology Question Thread
« Reply #11270 on: October 31, 2018, 10:30:45 pm »
0
how does a combination of selection pressures and restricted gene flow result in a new species?
thank you!
In order for a speciation to occur, two (or more) genetically isolated populations need to be exposed to different selection pressures. A species is genetically isolated when gene flow is restricted and this is important as it allows differences to accumulate. Also, stronger or multiple selection pressures acting on the isolated populations would aid is faster speciation as it would cause a more rapid change in phenotype contributing to differences between the populations (assuming they are not so strong that they cause the death of the population).
When talking about speciation, make sure to establish that speciation has occurred when (and only when) the two populations have become reproductively isolated and thus cannot mate to give fertile viable offspring.
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011116

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Re: VCE Biology Question Thread
« Reply #11271 on: October 31, 2018, 10:34:39 pm »
0
I'm just going to copy it from my notes given I don't know how much you already know about them. Let me know if you have questions about any of this.

Malfunctions in apoptosis
Cancer is caused by a damaged cell not undergoing apoptosis. These cells divide rapidly, creating large lumps called tumours. There are many reasons why apoptosis fails to occur.
Overactive apoptosis: Leads to diseases such as Huntington’s, Alzheimer’s, type 1 diabetes
Underactive apoptosis: Leads to diseases such as cancer.

Apoptosis
Triggers:
-Cellular injury
-DNA damage
-Viral infection
-Old age
-Cell no longer needed

Mitochondrial (intrinsic) pathway:
A signal causes the mitochondria to release cytochrome C (a protein usually involved in the electron transport chain). Cytochrome C activates caspases in the cell.
When mitochondria are damaged they release signals called cytochromes. They act as signalling molecules for intracellular receptors that initiate apoptosis.

Death receptor (extrinsic) pathway:
Initiated by a signalling molecule binding to a death receptor, which causes the activation of enzymes called caspases.

Apoptosis:
Caspases are activated by either of the apoptotic pathways. Caspases are enzymes that cleave protein molecules, breaking down the cytoskeleton of the cell, as well as other proteins in the cytoplasm and nucleus. The caspases activate other enzymes called DNAses, which cut nuclear DNA. Blebs form on the surface of the cell, and the cell fragments into a group of vesicles. The contents of the cell never enter their environment, and are always contained within a phospholipid bilayer. The vesicles (or ‘blebs’ or ‘apoptotic bodies’) are engulfed by phagocytes (e.g. macrophages), and their contents are recycled.
thank you so much, u know how u stated "many reasons why apoptosis occurs" do we need to know the reasons
once again thank you

PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11272 on: October 31, 2018, 10:39:05 pm »
+1
thank you so much, u know how u stated "many reasons why apoptosis occurs" do we need to know the reasons
once again thank you
You mean in the malfunctions part? You don't need to know them. You should be aware of the normal triggers for apoptosis though.
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Erutepa

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Re: VCE Biology Question Thread
« Reply #11273 on: October 31, 2018, 10:40:05 pm »
+2
can someone please explain to me, the malfunctions in apoptosis that result in deviant cell behavior leading to disease including cancer and also the intrinsic and extrinsic pathway?

Thank you
Normally in cells, there are pro-apoptotic and anti-apoptotic singles which regulate normal cell life and death. Generally stated, In cancer which avoids apoptosis, expression of pro-apoptotic signals is downregulated and anti-apoptotic singles are up-regulated. Cancer cells might even also prevent expression of crucial proteins needed in apoptosis pathways, resulting in the absence of apoptosis.
Don't need to know this though. I won't explain intrinsic or extrinsic pathways, PF's notes do that well.
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Hirul1280

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Re: VCE Biology Question Thread
« Reply #11274 on: November 01, 2018, 12:43:05 am »
0
How does B-cell activation work?
Why is IgM the default antibody? Why does it change to IgG later on?

EllyJayne

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Re: VCE Biology Question Thread
« Reply #11275 on: November 01, 2018, 07:50:41 am »
0
do we have to know about macromolecules for the exam?

darkz

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Re: VCE Biology Question Thread
« Reply #11276 on: November 01, 2018, 08:00:52 am »
+1
do we have to know about macromolecules for the exam?
Yes, you should know about nucleic acids and proteins rather well, however you should also know that the other two categories are lipids e.g. triglyceride and carbohydrates e.g. glucose (details about them not required I believe)
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galaxy21

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Re: VCE Biology Question Thread
« Reply #11277 on: November 01, 2018, 08:01:05 am »
0
Hi,
What do we need to know about mass extinctions? Is it just some of the major causes and what follows?
Also, what would be some of the major causes of mass extinctions? Is it like big changes of climate, like the ice age and stuff?
Thanks!
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darkz

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Re: VCE Biology Question Thread
« Reply #11278 on: November 01, 2018, 08:04:51 am »
+5
Hi,
What do we need to know about mass extinctions? Is it just some of the major causes and what follows?
Also, what would be some of the major causes of mass extinctions? Is it like big changes of climate, like the ice age and stuff?
Thanks!

Yup, so climate change is a big one i.e. changes in sea level etcetera. Another one would be the asteroid collisions which wiped out most of the dinosaurs. You should also know that mass extinctions are followed by a period of adaptive radiation, due to the vast number of unoccupied ecological niches
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11279 on: November 01, 2018, 08:07:58 am »
0
How does B-cell activation work?
Why is IgM the default antibody? Why does it change to IgG later on?
B cells are initially activated by a free antigen (one not presented on MHC) and then they are activated by a Th cell that has been presented with its antigen. Both of these are required for a naive B cell to divide and differentiate.

You don't need to know any of that.
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