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March 29, 2024, 09:04:34 am

Author Topic: VCE Biology Question Thread  (Read 3570990 times)  Share 

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natalie03

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Re: VCE Biology Question Thread
« Reply #12315 on: February 16, 2020, 10:14:49 am »
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I feel like this is the dumbest question but could someone please explain the surface area to ratio volume to me please? thank you xo

SmartWorker

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Re: VCE Biology Question Thread
« Reply #12316 on: February 16, 2020, 10:26:30 am »
+8
I feel like this is the dumbest question but could someone please explain the surface area to ratio volume to me please? thank you xo

So, first we must understand why SA:V ratio is important:
1. All cells must maintain an efficient two-way exchange of materials to sustain life.

This is gross simplification, imagine this, if you whole body is one cell, how would your inner components get oxygen in time, it would take a long time.

So, by having an extremely small cell, nutrients will can be taken up and waste can be expelled quickly

Using a bit of math, try make sense of the diagram attached.
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #12317 on: February 16, 2020, 11:37:10 am »
+2
How much do we need to know about the structure of pathogens? Also do we need to know about Gram-positive and Gram negative bacteria?

Thanks
The study design also specifies cellular & non cellular so you should be able to identify that if you're given an example of a pathogen.
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natalie03

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Re: VCE Biology Question Thread
« Reply #12318 on: February 16, 2020, 06:26:22 pm »
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So, first we must understand why SA:V ratio is important:
1. All cells must maintain an efficient two-way exchange of materials to sustain life.

This is gross simplification, imagine this, if you whole body is one cell, how would your inner components get oxygen in time, it would take a long time.

So, by having an extremely small cell, nutrients will can be taken up and waste can be expelled quickly

Using a bit of math, try make sense of the diagram attached.
thank you heaps  :)

jacquii02

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Re: VCE Biology Question Thread
« Reply #12319 on: February 22, 2020, 09:31:51 pm »
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what is the difference between structural and regulatory genes??
the textbook says that regulatory genes code for proteins that regulate gene expression. does that mean that the repressor protein in the lac operon is a regulatory gene?
please help
thanks

Geoo

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Re: VCE Biology Question Thread
« Reply #12320 on: February 22, 2020, 09:54:43 pm »
+4
what is the difference between structural and regulatory genes??
the textbook says that regulatory genes code for proteins that regulate gene expression. does that mean that the repressor protein in the lac operon is a regulatory gene?
please help
thanks
Structural genes code for structural protein. This could be keratin, which is a protein that makes up skin, hair and nails. So structural genes basically make proteins that can be used to build something in a sense. Regulatory proteins make proteins that regulate other genes. So yes, a repression protein would be made, which is used in the lac operon. Regulatory genes can make proteins that turn genes on and off life a switch, which are used in gene regulation. Hope this helps :)
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Amnilauv

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Re: VCE Biology Question Thread
« Reply #12321 on: February 26, 2020, 09:13:19 pm »
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Can someone explain how to get the answer to the 2019 biology exam, question 39 multiple choice?

The number of restriction sites cut are 4, so that rules out a and b. However, I thought that the number of fragments would be 5 as the restriction enzymes at the last HincII would stop at the ORI. Or, is the ORI even a part of the plasmid? What does it even mean?
The answer is C.

coldairballoon

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Re: VCE Biology Question Thread
« Reply #12322 on: February 26, 2020, 09:21:20 pm »
+6
Can someone explain how to get the answer to the 2019 biology exam, question 39 multiple choice?

The number of restriction sites cut are 4, so that rules out a and b. However, I thought that the number of fragments would be 5 as the restriction enzymes at the last HincII would stop at the ORI. Or, is the ORI even a part of the plasmid? What does it even mean?
The answer is C.

The ORI isn't really important in the context, just pretend it's not there. It's just a site on the plasmid that's used in DNA replication, and the question doesn't say that a restriction enzyme that cuts at ORI is used. Since there are 4 restriction sites and the plasmid is circular, you end up with 4 fragments, so C.
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Sine

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Re: VCE Biology Question Thread
« Reply #12323 on: February 26, 2020, 09:25:54 pm »
+4
Can someone explain how to get the answer to the 2019 biology exam, question 39 multiple choice?

The number of restriction sites cut are 4, so that rules out a and b. However, I thought that the number of fragments would be 5 as the restriction enzymes at the last HincII would stop at the ORI. Or, is the ORI even a part of the plasmid? What does it even mean?
The answer is C.
ORI is the origin of replication - basically where the plasmid would open up to start the process of DNA replication just like in humans.
You are correct that 4 restriction sites are cut but the number of pieces produced are 4.

However, you would be correct if this piece of DNA was linear (5 pieces would be produced).

PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #12324 on: February 27, 2020, 07:27:02 am »
+4
^For these sorts of questions, it'll be easier to just grab a pen and draw a big line where the enzyme cuts so that you can just count the number of sites & fragments.
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Mudasser.abb

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Re: VCE Biology Question Thread
« Reply #12325 on: February 29, 2020, 08:44:31 pm »
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Any tips for enzymes sac?

J_Rho

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Re: VCE Biology Question Thread
« Reply #12326 on: March 01, 2020, 09:52:09 am »
+9
Any tips for enzymes sac?
Make sure you are able to describe in detail everything about enzymes -
- the structure and features of enzymes
- what an enzyme catalysed reaction looks like (how substrates are turned into products)
- optimal temperature/pH and what happens when they are denatured (and whether it is reversible)
- substrate concentration and enzyme concentration (including saturation)
- enzyme inhibitors; competitive and non-competitive inhibition
- reversible vs irreversible inhibition
- cofactors and coenzymes
- the cycling of coenzymes such as ADP/ATP, NADH/NAD+, and NADPH/NADP+

Enzyme - Practice Questions
There's only 12 questions there but I would recommend using checkpoints or asking your teacher for a practice sac/practice questions also
Hope this helped :)
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Azila2004

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Re: VCE Biology Question Thread
« Reply #12327 on: March 01, 2020, 01:56:42 pm »
+1
Hello!  ;D

I was wondering: which cells specifically release interferons (or just cytokines)? I am a little confused about what mast cells are, and whether the cell has to be infected or not to release these signalling molecules.

Thank you. 
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Evolio

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Re: VCE Biology Question Thread
« Reply #12328 on: March 01, 2020, 02:55:09 pm »
+4
Hey!  ;D
It's been a while since I did Biology so I'll try answer these as best as I can.

Interferons are released by virus-infected cells to warn uninfected cells, thus making them release antiviral proteins to build up their defences against viruses so that they do not become infected as well. This is to prevent the spreading of the virus infection.

Also, mast cells are a type of white blood cell so they are not signalling molecules. Mast cells are phagocytes which means that they engulf and digest foreign material of pathogens and they are also involved in the allergic response. They are mainly involved in the inflammatory response where they release histamine which causes inflammation. That is, they make the blood vessels dilate to increase blood flow to the area, bringing in more cells. Mast cells also release signalling molecules to other white blood cells which then migrate to the site of infection.
I am pretty sure that mast cells are activated, which then allows them to play their role in the inflammatory response.

Hope this helps.

J_Rho

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Re: VCE Biology Question Thread
« Reply #12329 on: March 01, 2020, 02:59:42 pm »
+4
Hello!  ;D

I was wondering: which cells specifically release interferons (or just cytokines)? I am a little confused about what mast cells are, and whether the cell has to be infected or not to release these signalling molecules.

Thank you.

Hi Azila,

In my understanding, any virus-infected cell will release interferons to signal other 'healthy' cells to prepare to defend against the virus, which aims to limit the spead of the virus.

Mast cells are found in connective tissues and are involved in inflammation and allergic responses. They circulate the lymphatic system in an immature form and mature once they reach connective tissue. They secrete histamines, a type of signalling molecule, which causes dilation of blood vessels, fever/heat (increases enzyme activity, decreased bacterial growth rate and can kill some pathogens), increased the permeability of capillaries (allows phagocytes to pass easily from blood to infected tissue) and swelling (permeability allows fluid to enter tissues (also limits the movement of pathogens)) and attracts phagocytes.

I feel like I went off track to your question, sorry
Hope this helps :)





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Bachelor of Nursing @ Monash
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