VCE Biology Question Thread

[Monkeymafia]

I can't find a clear answer online, so thought I would post here.

What effect would temperature, ph and alcohol have on the structure of cell walls? 

Thanks.

[PhoenixxFire]

Hey, did you mean cell membranes? I don’t know how it affects plant walls, but I never learnt it so you don’t need to know, unless it’s something extra your teacher wants you to learn.

For cell membranes:
Temperature and pH cause the cell to become ‘leaky’, this means that the membrane is more fluid. Cholesterol can regulate the membranes fluidity so that slight temperature changes will not affect it, I don’t know if there is a similar mechanism for pH.

Alcohol damages the cell membrane, but that’s all I know about it.

I’m pretty sure we talked about this last year though, so someone around here probably knows.

Edit: Typos

[Monkeymafia]

Hey,

Yeh I meant cell walls. I know about the effects of temperature on plant cell membranes, but I am not sure if temperature affects cell walls (or if it affects cellulose).

[Monkeymafia]

For anaerobic respiration, why do different organisms produce different products?

Yeast - ethanol + carbon dioxide
Bacteria - Lactic acid

[PhoenixxFire]

Physiologically its because they follow different metabolic pathways, they have different enzymes that cause the breakdown into different products. I don't know why they evolved differently though - Possibly something to do with the organisms ability to get rid of the waste product.

[011116]

in terms of learning the content, any home study methods/tips that i could use 

[PhoenixxFire]

Hey,
You can read a guide to studying bio that I wrote here. There are also other bio guides and resources here.

Google ‘douchys biology podcast’ or look it up in the ios podcast app. It’s a free podcast specifically for vce bio.

[Bri MT]

in terms of learning the content, any home study methods/tips that i could use 

The main thing I did was smash out exam questions. Aside from that, tables and diagrams are often very useful in bio & drawing them up and sticking them somewhere you will often see them aids remembering the content and connections between ideas.

[Sine]

in terms of learning the content, any home study methods/tips that i could use 

although I didn't use it during vce khan academy usually explain concepts simpler and more clear than any teacher ever could. Once you have learnt all the concepts you just need to churn out exams and learn how to word and phrase your answers which can be helped by checking answers.

[Bri MT]

although I didn't use it during vce khan academy usually explain concepts simpler and more clear than any teacher ever could. Once you have learnt all the concepts you just need to churn out exams and learn how to word and phrase your answers which can be helped by checking answers.

Note on this: KhanAcademy can be great but goes well and truly beyond the study design at some points so don't panic if you have trouble with some of the things they discuss.

[Hiea]

Hi everyone!

How are ion channels + gated ion channels and channel proteins + carrier proteins related? I assume they're all different classifications of transport proteins, but I don't really understand how they overlap and connect (if at all) and the exact distinctions they each have. For example, are carrier proteins a form of gated ion channel? How so? It's all quite confusing to me. 

[Calebark]

Hi everyone!

How are ion channels + gated ion channels and channel proteins + carrier proteins related? I assume they're all different classifications of transport proteins, but I don't really understand how they overlap and connect (if at all) and the exact distinctions they each have. For example, are carrier proteins a form of gated ion channel? How so? It's all quite confusing to me. 

I don't know how much detail is needed for the new study design, so please bear with me -- hopefully somebody more learned can come along and help. At least in my study design, I was never asked too much detail on these.

There are two types of transport proteins, being carrier proteins and channel proteins.

Carrier proteins are glycoproteins embedded in the cell membrane that carry specific large molecules.. The solute will bind to one side of the carrier protein. The carrier protein will move shape in a way that will move the solute into the cell, where it is then released (the mechanisms of how exactly are beyond VCE). Carrier proteins can move items passively (via facilitated diffusion) or through through active transport. This means that it can move against the concentration gradient.

Channel proteins are lipoproteins embedded in the cell membrane.Rather than allowing the substance to bind to them, they have a pore which substances travel through. They can only undergo passive transport (via facilitated diffusion), so they cannot go against the concentration gradient. Some of these channel proteins also carry ions, which is where ion channels come in.

[PhoenixxFire]

Carrier proteins are not a type of gated ion channel - ion channels are strictly for ions whereas carrier proteins can transport other molecules too.

You don't need to know much about ion channels, the only thing I know about them is that they are involved in the movement of neurotransmitters and very generally how they work (for VCE, they pretty much work the same as carrier proteins).

[011116]

Hi, can someone explain compartmentalization i dont get it?

[PhoenixxFire]

Hi, can someone explain compartmentalization i dont get it?

Hey,
Basically it allows different environments. It is when an area is separated from its environment by a membrane.

For example one organelle might need more of a substance than another organelle. Compartmentalisation means that the organelle can pump that substance inside and keep it there in higher concentration.

This also works between cells, for example a heart cell might need more glucose than blood cell. If there wasn’t compartmentalisation, they could not have different concentrations. This also applies for allowing slightly different conditions, eg. pH

Imagine your street is an organism. Each house is a cell (compartment). It’s a really hot day, so you all have your air conditioners on, but you’re all fussy people and like having your aircons set to different temperatures. If the house walls (cell membrane) were not there, you could not have different temperatures, and the cool air would escape into the street.