VCE Biology Question Thread

[neurons]

How do we draw a line of best fit for data points that follow a non-linear trend?
(eg. effect of temperature on enzyme activity with data for specific temperatures)

Would we draw a curve through the data points or a straight line (although that doesn't represent the trend very well?) or something else?

Thank you! 

[nguyh17]

Why is the primary structure unaffected during denaturation? And what can actually break down the primary structure? Thanks

[qwertyqwerty]

Why is the primary structure unaffected during denaturation? And what can actually break down the primary structure? Thanks

Peptide bonds are stronger than hydrogen bonds (which can break down during denaturation). Enzymes can break down the primary structure.

[vox nihili]

Why is the primary structure unaffected during denaturation? And what can actually break down the primary structure? Thanks

Just to add to above response, if you continue to heat a mixture, for instance, one would expect the peptide bonds to break too. In the biologicalworld though, this rarely, if ever happens.

[Photon]

Hey guys,

We did a a liver prac yesterday in which we added hydrogen peroxide to: sand, fresh liver with sand, boiled liver with sand and a grounded liver with sand. We used sand to help ground the liver and so it became a controlled variable across all test tubes. We then conneced the tubes to graduated cyllinders that we filled with water (completely) to observe if any gas is released.

I got the same results for both my fresh liver as well as my grounded liver. Shouldn't the grounded liver release more gas because catalse is intercellular and so the more surface area results in more gas being released?

Thanks.

[Photon]

I read somewhere that cofactors don't get used up in reactions, but isn't ATP a cofactor that is broken down in to ADP and a phosphate after a reaction?

[nguyh17]

How does the formation of a enzyme/substrate complex lower the activation energy in a condensation reaction? Really stuck on this one if someone could provide an explanation please!! 

[Gogo14]

I read somewhere that cofactors don't get used up in reactions, but isn't ATP a cofactor that is broken down in to ADP and a phosphate after a reaction?

ATP is not used up, only the energy stored in the bonds are used up. ADP and Pi is basically just ATP, but separated.

How does the formation of a enzyme/substrate complex lower the activation energy in a condensation reaction? Really stuck on this one if someone could provide an explanation please!! 

The complex weakens the bonds in the substrate, and helps the substrates combine easier.

[johnhalo]

With cellular respiration and photosynthesis, is there anything other than inputs/outputs and the structures of their respective organelles you really need to know?

[Photon]

With cellular respiration and photosynthesis, is there anything other than inputs/outputs and the structures of their respective organelles you really need to know?

You also need to know where each reacrtion takes place. Other than that VCAA doesn't realy ask for much.

[vox nihili]

Hey guys,

We did a a liver prac yesterday in which we added hydrogen peroxide to: sand, fresh liver with sand, boiled liver with sand and a grounded liver with sand. We used sand to help ground the liver and so it became a controlled variable across all test tubes. We then conneced the tubes to graduated cyllinders that we filled with water (completely) to observe if any gas is released.

I got the same results for both my fresh liver as well as my grounded liver. Shouldn't the grounded liver release more gas because catalse is intercellular and so the more surface area results in more gas being released?

Thanks.

Yes, I suspect you're right. I don't know why you got those results, that's odd.

How does the formation of a enzyme/substrate complex lower the activation energy in a condensation reaction? Really stuck on this one if someone could provide an explanation please!! 

If people have heard other explanations other than Gogo14's, that's fine too. There are actually a heap of ways by which enzymes can lower activation energy. Mercifully, you don't need to know them.

I read somewhere that cofactors don't get used up in reactions, but isn't ATP a cofactor that is broken down in to ADP and a phosphate after a reaction?

Yeah, imo not really a cofactor in that case.

[Gogo14]

Hey just wondering for the liver prac posted before, why is sand used? Can't you conduct the experiment without sand?

[blacksanta62]

Another question about the liver prac (already completed a couple days ago so I'm not cheating or anything ). A question asked us to discuss the induced fit model and provide a diagram (1 mark). In class my teacher had mentioned that the induced fit model suggests that while enzymes are still highly specific they can lower their specificity for similar shaped substrates. I wasn't sure whether or not to mention this (I did) and I'm hoping I didn't throw the mark away. Is this true or was I just dreaming it up

As for the crushing of sand, I really don't know. Hopefully someone can fill us both in. However I think the sand makes it finer when grounding it (not 100% sure) and I believe the experiment can still be conducted without it. Someone please explain why though

[vox nihili]

Another question about the liver prac (already completed a couple days ago so I'm not cheating or anything ). A question asked us to discuss the induced fit model and provide a diagram (1 mark). In class my teacher had mentioned that the induced fit model suggests that while enzymes are still highly specific they can lower their specificity for similar shaped substrates. I wasn't sure whether or not to mention this (I did) and I'm hoping I didn't throw the mark away. Is this true or was I just dreaming it up

As for the crushing of sand, I really don't know. Hopefully someone can fill us both in. However I think the sand makes it finer when grounding it (not 100% sure) and I believe the experiment can still be conducted without it. Someone please explain why though

Not really sure what you mean about lowering specificity for similar shaped substrates. Explain more?

I suspect that's right about the sand. It just helps ground the liver

[Photon]

Hey just wondering for the liver prac posted before, why is sand used? Can't you conduct the experiment without sand?

We used sand with one of the livers to help ground it. Then because we added it to one of the livers then we need to add it to the rest. Hence it became a controlled variable.