VCE Biology Question Thread

[vox nihili]

Thank you Mr. T-Rav!!

So, when it says list two proccesses that cannot occur if protein channels were not present in the plasma membrane:

Facilitated diffusion via protein channels cannot occur, but what would be the second process?

Honestly, I'm not sure. There are a few things that could apply, but they're not relevant to the VCE course in the slightest...and they all involve facilitated diffusion.

[cosine]

Honestly, I'm not sure. There are a few things that could apply, but they're not relevant to the VCE course in the slightest...and they all involve facilitated diffusion.

Could it be reasonable if the question meant by 'protein channels' by protein channels and carrier proteins? Hence the two processes would be active transport and facilitated transport. This is why i asked if protein channels and carriers are the same

[Jay.C]

Hi guys I've just had my 'movement across the cellular membrane' sac and I would just like to know if these were adequate sac responses to the following questions.

1. What could be a function of an alpha helix in albumin?

Alpha helices can provide elasticity to a protein, in albumin this elasticity may help provide protection for the egg yolk.

2. List the differences between Active transport and osmosis.

Active transport is the net movement of molecules through a partially permeable membrane from a low concentration to a high concentration, this process requires ATP. Where as osmosis the net movement of water molecules through a partially permeable membrane from an area of low solute concentration to an area of high solute concentration, this process does not require energy. Active transport occurs through carrier proteins where as osmosis occurs though aquaporin's.

[vox nihili]

Hi guys I've just had my 'movement across the cellular membrane' sac and I would just like to know if these were adequate sac responses to the following questions.

1. What could be a function of an alpha helix in albumin?

Alpha helices can provide elasticity to a protein, in albumin this elasticity may help provide protection for the egg yolk.

2. List the differences between Active transport and osmosis.

Active transport is the net movement of molecules through a partially permeable membrane from a low concentration to a high concentration, this process requires ATP. Where as osmosis the net movement of water molecules through a partially permeable membrane from an area of low solute concentration to an area of high solute concentration, this process does not require energy. Active transport occurs through carrier proteins where as osmosis occurs though aquaporin's.

1. Yes that's probably fine, although it's technically incorrect. Albumin is a protein that carriers lots of things, it's not structural. With that said, there's no reason for you to know that already and, as such, you shouldn't be disadvantaged by that.

2. You've correctly described both processes. You perhaps should have mentioned that osmosis occurs via the bilayer itself, as well as via aquaporins. It's also remiss of you to have not mentioned concentration gradients. Active transport occurs against the concentration gradient, osmosis occurs with it. You have described this by indicating from low to high or from high to low, but concentration gradient is an important term that perhaps should have been used.

All in all I think you're ok.

Could it be reasonable if the question meant by 'protein channels' by protein channels and carrier proteins? Hence the two processes would be active transport and facilitated transport. This is why i asked if protein channels and carriers are the same

It could, but the question would be a bit silly in that regard. Carrier proteins and channel proteins are fundamentally different. Though, from time to time, the authors of such questions do make mistakes like that. You know you're getting good at Biol when you can work out what they actually meant :p

[twinkling star]

Had a couple of questions:

- How does the smooth endoplasmic reticulum detoxify drugs and poisons?

- What is the role of the Golgi apparatus in post-translational modification?

- How would you define 'secretion', and what characteristics of secretion differentiate it from excretion?

- Why do some liver cells have 2 nuclei?

- If a liver cell does have 2 nuclei, is that cell tetraploid?

Thanks!

[cosine]

You know you're getting good at Biol when you can work out what they actually meant :p

You flatter me :3

[vox nihili]

Had a couple of questions:

- How does the smooth endoplasmic reticulum detoxify drugs and poisons?

- What is the role of the Golgi apparatus in post-translational modification?

- How would you define 'secretion', and what characteristics of secretion differentiate it from excretion?

- Why do some liver cells have 2 nuclei?

- If a liver cell does have 2 nuclei, is that cell tetraploid?

Thanks!

1. Enzymes

2. That it does it.

3. I want you to try to answer this one before I do.

4. Not important.

5. If the nuclei each have a diploid set of chromosomes, it is indeed.



Those answers are all the answers you'd need for VCE. In regards to 1 and 2, you just need to know that that's what happens, not how it happens. The smooth ER detoxifies because it contains a number of enzymes that modify the chemical structure of toxins, thus rendering them non-toxic. In terms of the Golgi, it adds on sugar or lipid groups to proteins via enzymes present in it.

[twinkling star]

Many thanks Mr. T-Rav!

3. I want you to try to answer this one before I do.

Would I be right in saying that 'secretion' is when a useful substance is released by a cell, gland or organ whereas 'excretion' is when a metabolic waste is expelled by a cell, gland or organ?

[thushan]

You could say that yup!

[Sine]

Are these correct statements?

Proteins are synthesised by the ribosome they enter endoplasmic reticulum tubules and are transported around the cell. The Golgi Apparatus then packages and modifies the protein before being placed in a vesicle for export out of the cell.

[vox nihili]

Are these correct statements?

Proteins are synthesised by the ribosome they enter endoplasmic reticulum tubules and are transported around the cell. The Golgi Apparatus then packages and modifies the protein before being placed in a vesicle for export out of the cell.

The ribosome isn't one thing, there are plenty of them. Proteins enter the rough endoplasmic reticulum.

Otherwise fine.

[Sine]

Thanks for the clarification.   

[cosine]

Are these correct statements?

Proteins are synthesised by the ribosome they enter endoplasmic reticulum tubules and are transported around the cell. The Golgi Apparatus then packages and modifies the protein before being placed in a vesicle for export out of the cell.

There are free ribosomes (cytoplasmic ribosomes) and ribosomes attached to the rough endoplasmic reticulum. Both of the ribosomes synthesise proteins, however, the free ribosomes (roaming around in the cytosol) produce proteins that are not transported out of the cell, in other words, they make proteins for the cell to use. However, the ribosomes on the endoplasmic reticulum produce proteins that are transported to the golgi complex through temporary vesicles. Once reached the golgi complex, they are properly packaged into vesicles known as secretory vesicles (secretory = to release, to make) which eventually fuse with the plasma membrane, and release the protein to the extracellular environment.

Hope it helped

Beaten by Mr. T-Rav :3

[Sine]

There are free ribosomes (cytoplasmic ribosomes) and ribosomes attached to the rough endoplasmic reticulum. Both of the ribosomes synthesise proteins, however, the free ribosomes (roaming around in the cytosol) produce proteins that are not transported out of the cell, in other words, they make proteins for the cell to use. However, the ribosomes on the endoplasmic reticulum produce proteins that are transported to the golgi complex through temporary vesicles. Once reached the golgi complex, they are properly packaged into vesicles known as secretory vesicles (secretory = to release, to make) which eventually fuse with the plasma membrane, and release the protein to the extracellular environment.

Hope it helped

Beaten by Mr. T-Rav :3

Thanks for the quick reply 

[Jay.C]

Just wondering what percentage equates to the sac grades of A+, A and B+, B?