VCE Biology Question Thread

[cosine]

Hey could somebody give an explanation of what is osmotic pressure and give a definition of it as well???

Osmotic pressure is the pressure that is referred to when water diffuses into the high solute concentrated region. It's like a measure of the concentration of solute, the higher it is, the osmotic pressure would also be larger because the water wants to equilibrate the concentrated solute even more, where as if there is such low concentration of the solute, then there would be less osmotic pressure because the water isn't pressured that heavily to equilibrate the solute. Hope this helps xD

[gameboy99]

Osmotic pressure is the pressure that is referred to when water diffuses into the high solute concentrated region. It's like a measure of the concentration of solute, the higher it is, the osmotic pressure would also be larger because the water wants to equilibrate the concentrated solute even more, where as if there is such low concentration of the solute, then there would be less osmotic pressure because the water isn't pressured that heavily to equilibrate the solute. Hope this helps xD

Thanks! That makes it simple to understand.

[gameboy99]

Why do people spray water to fresh fruits and vegetables in grocery stores? Is it to maintain tugor pressure. Can someone explain??

[cosine]

Why do people spray water to fresh fruits and vegetables in grocery stores? Is it to maintain tugor pressure. Can someone explain??

Water is sprayed so that it can simply diffuse through the fruit cells and the cells will now have an excess of turgor pressure, meaning they will swell up and hence will look more appealing to the eyes of customers.

[gameboy99]

Do you think I need to know both the mitochondrial pathway and death receptor pathway for apoptosis for bio exam? And if so how much detail?? 

[cosine]

Do you think I need to know both the mitochondrial pathway and death receptor pathway for apoptosis for bio exam? And if so how much detail??

No you don't need to know neither of those. All you need to know about apoptosis is that it is programmed cellular death, and that the signal can be intracellular or extracellular. Apoptosis is something you should know exists, but not much, if any detail at all.

[Hayley_turnham]

A question in relation to movement across a cell membrane - how do you know which different ions and other substances pass through via facilitated diffusion or active transport? e.g. glucose is through active transport but calcium Ca2+ is through facilitated diffusion. Both are through either carrier proteins or protein channels. Are there a set few that we should be expected to just know ? Thank youu 

[sunshine98]

A question in relation to movement across a cell membrane - how do you know which different ions and other substances pass through via facilitated diffusion or active transport? e.g. glucose is through active transport but calcium Ca2+ is through facilitated diffusion. Both are through either carrier proteins or protein channels. Are there a set few that we should be expected to just know ? Thank youu 

I answered a similar question on the last page , here's a copy paste of it (its basically like a criterion you could follow to decide what method of movement )  :
-Simple diffusion : small molecules , hydrophobic/lipophilic, uncharged, nonpolar (eg: O2 , urea)
- Facilitated diffusion: large molecules , hydrophilic/ lipophobic , charged (including ions )  , polar  (eg: glucose due to its large size and polarity)
-Active transport :for this one , it is ANYTHING going against the concentration gradient

The reason Ca2+  is through facilitated is cause its an ion , and because glucose in this situation is being taken against the concentration gradient it would be active transport. The reason they use membrane proteins is cause both facilitated and active methods utilise membrane proteins.

Also, no I don't think you would need to know a set few. Its just if a question asks you about it , it will provide hints about the structure that will allow you to answer the question. Like it might say its polar and large , and you would say  facilitated .
hope this clears things up

[geminii]

Is it true we don't need to know anything about globular or fibrous proteins this year? If so, would learning about them anyway be helpful?

[sunshine98]

Is it true we don't need to know anything about globular or fibrous proteins this year? If so, would learning about them anyway be helpful?

Yep its true. Quote from vce bio faq published by VCAA 'Classifications of, and differences between, different types of proteins such as globular and fibrous proteins are not required' .Definitely download this document. It helps loads. Also , I don't think there's any point in bothering , unless you want to learn out of interest.

[Gogo14]

Yep its true. Quote from vce bio faq published by VCAA 'Classifications of, and differences between, different types of proteins such as globular and fibrous proteins are not required' .Definitely download this document. It helps loads. Also , I don't think there's any point in bothering , unless you want to learn out of interest.

Sorry, where do you find this information?

[TheAspiringDoc]

Sorry, where do you find this information?

http://www.vcaa.vic.edu.au/Pages/vce/studies/biology/biologyindex.aspx#H2N10088

[gameboy99]

What are integral proteins and what are their function in the PM???

[Gogo14]

What are integral proteins and what are their function in the PM???

They are proteins embedded in the PM. The functions of these proteins can vary. Some proteins are used as channels with a pore to allow certain substances to cross the membrane. Some are carrier proteins which allows one way movement of substances into/ out of the cell. Their function is to regulate the movement of substance whihc cannot pass the PM, in and out of the cell.

Another type of protein are glycoproteins which are anchored in the PM and are receptors or have signalling functions (e.g. Antibodies).

[geminii]

Hey everyone,
I got my SAC marks back today. Let's just say I'm not pleased (I got the average score of the class), and this is after studying all holidays and every moment I could. AND I knew what the prac was going to be about, and the EXACT prac we were going to do!!! By looking at my SAC comments I can see that I understood everything (aka I knew all the theory) but the way I structured my answers let me down. Can anyone please provide a foolproof way to answer biology questions? I know this question is broad but I can never seem to answer a question correctly (with the way I word my answer) and I really need to know how to answer questions properly before my next SAC in two weeks.
So does anyone have some tips on how to do this???
Thanks so much!