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March 28, 2024, 09:03:00 pm

Author Topic: VCE Biology Question Thread  (Read 3570375 times)  Share 

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Bri MT

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Re: VCE Biology Question Thread
« Reply #12375 on: March 26, 2020, 03:20:26 pm »
+2
Polar molecules are covalent molecules in which electrons are not evenly distributed, so some parts of the molecule are slightly negative while others are slightly positive. For example, the two hydrogen atoms in H2O molecules are slightly positive while the oxygen atom is slightly negative simply due to the fact that oxygen is more electronegative (has a greater electron attracting power). Non-polar molecules are the opposite as there is no overall unequal sharing of electrons.

EDIT: for the sake of Biology you just need to know that polar molecules interact with other polar molecules while non polar molecules interact with other non polar molecules.


The edit is a really common misunderstanding that you can usually get away with in VCE so I want to talk about that here:

Not that it's important for biology, but the idea of nonpolar interacts with nonpolar whereas polar interacts with polar is incorrect. Polar is attracted to polar, that's true, but the reason why non-polar molecules group together isn't because they experience stronger attraction to nonpolar than to polar; it's because the polar molecules are more strongly attracted to each other than they are to nonpolar molecules - and that leaves the nonpolar molecules "excluded" together. 


You are correct that:
-> molecules have covalent bonds
-> nonpolar molecules have roughly even electron density everywhere
-> polar molecules like water are so due to there being greater electron density around oxygen as it's electronegative

J_Rho

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Re: VCE Biology Question Thread
« Reply #12376 on: March 26, 2020, 03:32:06 pm »
0
alright so the bio Edrolo textbook is littered with small and usually undetectable typos.....the definition of a glycolipid is "a phospholipid, bound to a carbohydrate"
Is it the wrong way round? isnt it a carbohydrate bound to a phospholipid?
I am confused and this is so simple like i shouldn't be confused at all hahahaha
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #12377 on: March 26, 2020, 03:40:51 pm »
+3
alright so the bio Edrolo textbook is littered with small and usually undetectable typos.....the definition of a glycolipid is "a phospholipid, bound to a carbohydrate"
Is it the wrong way round? isnt it a carbohydrate bound to a phospholipid?
I am confused and this is so simple like i shouldn't be confused at all hahahaha

The whole thing is the glycolipid. The carbohydrate part is still a carbohydrate, the lipid part is still a lipid, glycolipid is just the name for the whole thing.

Also re: polar vs nonpolar, for bio you don't need to know about electrons and stuff, it's enough to just say that polar molecules have an unevenly distributed charge and non-polar molecules have an evenly distributed charge.
« Last Edit: March 26, 2020, 03:42:25 pm by PhoenixxFire »
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J_Rho

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Re: VCE Biology Question Thread
« Reply #12378 on: March 26, 2020, 03:46:56 pm »
0
The whole thing is the glycolipid. The carbohydrate part is still a carbohydrate, the lipid part is still a lipid, glycolipid is just the name for the whole thing.

Also re: polar vs nonpolar, for bio you don't need to know about electrons and stuff, it's enough to just say that polar molecules have an unevenly distributed charge and non-polar molecules have an evenly distributed charge.
Okay thanks for the clarification!
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Bri MT

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Re: VCE Biology Question Thread
« Reply #12379 on: March 26, 2020, 03:51:10 pm »
+3
alright so the bio Edrolo textbook is littered with small and usually undetectable typos.....the definition of a glycolipid is "a phospholipid, bound to a carbohydrate"
Is it the wrong way round? isnt it a carbohydrate bound to a phospholipid?
I am confused and this is so simple like i shouldn't be confused at all hahahaha


Imo they shouldn't have phospholipid in their definition at all. A glycolipid is just a lipid with a carbohydrate component. Generally the carbohydrate component would protrude on the exterior of a cell membrane which could give the appearance of carbohydrate attached to phospholipid but glycolipids don't need to have phosphate in them or to have 2 fatty acids.

Edit: pf bet me but I think my commentary might still be valuable :)

kasthury610

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Re: VCE Biology Question Thread
« Reply #12380 on: March 27, 2020, 09:09:56 pm »
0
Hi there,
can someone explain about the lac operon?
I'm quite confused about it. :)

SS1314

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Re: VCE Biology Question Thread
« Reply #12381 on: March 27, 2020, 11:44:59 pm »
+7
Hi there,
can someone explain about the lac operon?
I'm quite confused about it. :)

Hey

An operon is a group of linked structural genes, that are transcribed together, with a common promoter (binding site of RNA polymerase) and operator (binding site of repressor protein).

The lac operon is a specific type of operon found in E. coli bacteria located in our gut. The lac operon contains three structural genes that encode the information for the synthesis of lactase (an enzyme that breaks down the sugar lactose).

However, the thing is that E. coli bacteria prefer glucose over lactose so when glucose is around (or when there is no lactose in the first place), synthesising lactase would be a complete waste of energy - this is where the regulatory gene comes in.

The regulatory gene is located right next to the lac operon and codes for the synthesis of a repressor protein (a transcription factor) . Remember how I mentioned the operator region earlier? The thing is that the operator is located right in between the promoter region (where RNA polymerase binds) and the 3 structural genes coding for the synthesis of lactase. So when the regulatory gene is transcribed, and all the normal translation stuff happens, a repressor protein is synthesised which binds to the operator region, pretty much blocking RNA polymerase from being able to transcribe the 3 genes.

In the above explanation, it is assumed that lactose is absent, however when E. coli obtain lactose (and no glucose) something bizarre happens. The lactose in the cytosol actually binds to the repressor protein that has been synthesised, rendering it inactive. This results in the RNA polymerase being able to move past the promoter region and freely transcribe the structural genes, which in turn leads to translation and finally the synthesis of lactase which breaks down the lactose.

Have you picked up the cycle yet? As soon as the lactose runs out (i.e. all of it has been broken down by the lactase molecules), the repressor protein straight away starts to block the RNA polymerase from transcribing the genes until more lactose is obtained.

This mechanism prevents bacteria from wasting energy producing excess amounts of lactase molecules that can't do anything when there is not lactose.

Hope this helps  :)



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amanaazim

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Re: VCE Biology Question Thread
« Reply #12382 on: March 28, 2020, 08:56:34 pm »
0
what is the easiest way to learn the cells part, and plasma membrane part of biology

amanaazim

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Re: VCE Biology Question Thread
« Reply #12383 on: March 28, 2020, 09:07:05 pm »
0
does a eukaryote cell have ribosomes

SS1314

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Re: VCE Biology Question Thread
« Reply #12384 on: March 28, 2020, 09:12:06 pm »
+1
does a eukaryote cell have ribosomes

Yes

In fact EVERY cell has ribosomes (both prokaryotes and eukaryotes)
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J_Rho

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Re: VCE Biology Question Thread
« Reply #12385 on: March 28, 2020, 10:04:43 pm »
0
what is the easiest way to learn the cells part, and plasma membrane part of biology
IMO flashcards or drawing it
if you drew it you could make a big poster and also label parts and stick it on your wall so you're always looking at it
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amanaazim

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Re: VCE Biology Question Thread
« Reply #12386 on: March 29, 2020, 02:19:58 pm »
0
what does the ribosomes do in the atp cycle

amanaazim

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Re: VCE Biology Question Thread
« Reply #12387 on: March 29, 2020, 04:29:32 pm »
0
hey just wanted to ask the stages

glycolysis, kerb cycle and electron transport chain. what is this process for ?

Sine

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Re: VCE Biology Question Thread
« Reply #12388 on: March 29, 2020, 04:33:28 pm »
+1
hey just wanted to ask the stages

glycolysis, kerb cycle and electron transport chain. what is this process for ?
all three stages together form aerobic respiration and the purpose of this is to produce ATP which is the main energy source for our cells.

amanaazim

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Re: VCE Biology Question Thread
« Reply #12389 on: March 29, 2020, 04:40:12 pm »
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so it isn't the process of cellular respiration?

also i wanted to say that does anaerobic and aerobic respiration go through the same process, like where does it stop been the same can you explain that to me please.