VCE Biology Question Thread

[Nostalgia]

Since you are probably looking for the color change of the solution (as a result of cells containing pigment have their membrane disrupted) across exposure of the beetroot to difference chemicals, it is important that the beetroot doesn't have any pigments already on it from the cutting process. The washing is to remove any such excess pigments off the beetroot. Without washing the beetroot, solutions that shouldn't disrupt the membrane will show a colour change due to this excess pigment.
Not sure about the aeration though. It may just be in order to better preserve it.

Thanks for replying! Yeah, we were looking for the colour change and how red the solution was. Also, how do you explain the results in terms of the structure of the membranes? For example, the solution of the beetroot covered in pH2 was completely red, meaning that a lot of pigment leaked out of the beetroot cell, and the solution of the beetroot in pH10 was clear. So would this be explained like: alkaline solutions affect cell membranes by making them less permeable? Beetroot pigment turns colourless in alkaline solutions though, so I'm not sure. I'd appreciate any help... 

[Erutepa]

Thanks for replying! Yeah, we were looking for the colour change and how red the solution was. Also, how do you explain the results in terms of the structure of the membranes? For example, the solution of the beetroot covered in pH2 was completely red, meaning that a lot of pigment leaked out of the beetroot cell, and the solution of the beetroot in pH10 was clear. So would this be explained like: alkaline solutions affect cell membranes by making them less permeable? Beetroot pigment turns colourless in alkaline solutions though, so I'm not sure. I'd appreciate any help... 

Based on what results you have given, I think I would put it more like this way
The present of beetroot pigment within the solution pH 2, suggests that such low pH conditions may disrupt the integrity of the cell membrane which thus allows pigments to diffuse from the beetroot cells into the solution. The lack of any colour change visible at pH 10, suggests that at such high pH conditions, the cell membrane of beetroot cells are not disrupted and as such prevent the diffusion of pigments into the solution. However, at high pH condition, the pigment in beetroot is known to undergo a colour change and appear clear, thus proposing a limitation of the experiment as the lack of colour change in high pH condition may be attributed to the colour change of the pigment rather than the maintenance of membrane integrity.

I am a bit tired, so I apologize if this may sound a bit awkward. I am also assuming that this beetroot pigment does actually turn clear in alkaline conditions

[hcolomer]

In endocytosis, are contents released into the cytosol or in the golgi apparatus?

[vox nihili]

In endocytosis, are contents released into the cytosol or in the golgi apparatus?

Cytoplasm

[Evolio]

Hi.
I was wonderind what the differences and similarities are between the three forms of rna subunits?
Thanks.

[DBA-144]

Hi.
I was wonderind what the differences and similarities are between the three forms of rna subunits?
Thanks.

Your question is a bit vague.I might be missing something but the subunits of RNA are nucleotides. And the nucleotide is made up of a phosphate, ribose sugar and nitrogenous base, as I'm sure you're aware of.

Perhaps you mean the three different types of RNA? As in mRNA, tRNA and rRNA? I don't think you would need to know their strucutres, just a rough idea of how they look, I expect.

Sorry for the poor answer, I am unable to interpret what you mean here.

[jinaede1342]

Hi.
I was wonderind what the differences and similarities are between the three forms of rna subunits?
Thanks.

I'm going to assume that by "forms of subunits" you are talking about the types of RNA:    tRNA, mRNA and rRNA

tRNA - carries a specific amino acid to the ribosome for translation, and it does so as it has a specific anticodon that is complementary to the codon of the mRNA.

mRNA - is the product of transcription - RNA polymerase (enzyme) transcribes the DNA template strand which then results in a sequence of nucleotides complementary to template strand. The nucleotides are ‘read’ by the ribosome three at a time (codons).

rRNA - together with various proteins make up the ribosome.

Essentially, they all play roles in in transcription and translation which is required in order for cells to manufacture proteins (which are responsible for carrying out cell functions that sustain life).

Note: any RNA contains Adenine, Guanine, Cytosine and Uracil (no thymine!)

So similarities:
- they all have A,U,G,C bases

Differences:
- They all play different roles in protein synthesis as mentioned above
- They all have different structures, I’m not quite sure how to embed pictures just yet, but if you google them you will find that mRNA looks like a ‘spring’ or ‘coil’ whereas tRNA has a clover shaped ‘loop’ structure

Last year we were told that we should confidently be able to label and/or identify tRNA and its anticodon and also be able to provide sequences complimentary to any strands of RNA that we were provided with.

e.g. provide anticodon sequence for 'AUG'

Edit: sorry for doubling up with DBA-144, didn't realise that a response had been provided

[DBA-144]

Hi all,

1.what is required for the endosymbiotic theory?

Do we need to know simply the evidence for it, or also the origins of how, etc. and the events that lead to it as well?

Thank you.

[PhoenixxFire]

Hi all,

1.what is required for the endosymbiotic theory?

Do we need to know simply the evidence for it, or also the origins of how, etc. and the events that lead to it as well?

Thank you.

The study design just asks that you know about the evidence of bacterial origins. You'll also need to understand why that evidence supports the endosymbiotic theory though, rather than just memorising the evidence.

[stephfur]

Hi,

I've always thought that the photo synthesis equation was :
6CO2 + 6H2O = C6H12O6 + 6O2

and now all of a sudden by teacher this year is saying that it is:
6CO2 + 12H2O = C6H12O6 + 6CO2 + H2O

I'm a chem student so i get that they are both essentially the same equation, but as an overall equation, wouldn't you use the first equation and cancel the extra waters? She claims that you 'must' show that water is produced, but more water is used up than produced, so wouldn't you not show it in the equatIon? Please send help
Thanks

[Erutepa]

Hi,

I've always thought that the photo synthesis equation was :
6CO2 + 6H2O = C6H12O6 + 6O2

and now all of a sudden by teacher this year is saying that it is:
6CO2 + 12H2O = C6H12O6 + 6CO2 + H2O

I'm a chem student so i get that they are both essentially the same equation, but as an overall equation, wouldn't you use the first equation and cancel the extra waters? She claims that you 'must' show that water is produced, but more water is used up than produced, so wouldn't you not show it in the equatIon? Please send help
Thanks

You can use either the full equation or the net equation in the exam, but you may want to use the full equation in any SACs to avoid your teacher marking you wrong.

Also note that for your second equation, 6 water is produced as follows:
6CO2 + 12H2O = C6H12O6 + 6CO2 + 6H2O

[Blessing34]

Hi is anyone able to help me with this question from the biozone

What is meantby the active site of an enzyme and relate it to the enzyme's tertiary structure?

[PhoenixxFire]

Hi is anyone able to help me with this question from the biozone

What is meant by the active site of an enzyme and relate it to the enzyme's tertiary structure?

Hey, welcome to AN!
We'd love to help you to answer this, but us just giving you the answer isn't going to help you answer the next question you come across. What do you already know about how enzymes work? If you can elaborate a bit about what exactly it is that you're stuck on then we'll be able to help you much better

[DBA-144]

What does VCAA want us to know about the link reaction in respiration?

Do we include it as part of krebs, or separate from it, since the pyruvate is converted to acetyl coA so acetyl coA can be used as an input to krebs?(is this right)?

Thanks.

[zuijinde]

What does VCAA want us to know about the link reaction in respiration?

Do we include it as part of krebs, or separate from it, since the pyruvate is converted to acetyl coA so acetyl coA can be used as an input to krebs?(is this right)?

Link reaction is pretty much decarboxylation, and this does not happen in the krebs cycle.
A lot of mixed answers on whether there are 3 or 4 stages in celluar respiration, but I'd say link reaction would be considered a stage between glycolysis and krebs