Biology Exam: Answers and Discussion!

[Yacoubb]

Just interested in seeing what people wrote for q1C.

[Reus]

Do you mean 1bii?

[Yacoubb]

Do you mean 1bii?

Yeah sorry my bad! Had a lot of questions asking about it... I simply thought that the synthesised product (I forgot its name now) attaches to the allosteric region of the ATCase --> active site shape changes --> cannot properly bind to A and B substrate, production rate of D decreases as a result.

^ in simplified terms, of course.

[stirfrynoodles]

What did everyone write for question 3 in short answer? And was question 10 part a and b both monohybrid crosses? (if not then I am so dead  )

[Reus]

Yeah sorry my bad! Had a lot of questions asking about it... I simply thought that the synthesised product (I forgot its name now) attaches to the allosteric region of the ATCase --> active site shape changes --> cannot properly bind to A and B substrate, production rate of D decreases as a result.

^ in simplified terms, of course.

Yeah I wrote that the high production of CTP inhibits the rate of the enzyme ATCase in which the production of D is regulated in a decrease - thus an equilibrium. I didn't put much detailed into it however realising it was worth 3 marks now I wish I did haha

What did everyone write for question 3 in short answer? And was question 10 part a and b both monohybrid crosses? (if not then I am so dead  )

For 3a. I wrote about the binding to a plasma membrane receptor because of the hydrophilic property of the hormone. This initiates secondary messengers in which signal transduction takes place - cascade of events/chemical reactions. This then stimulates glycogenolysis where glycogen is converted to glucose. Glucose then leaves the liver going into the blood.

3b. A net movement of glucose molecules from a higher glucose concentration -inside the cell- to a lower glucose concentration -outside the cell-. The high concentration facilitates the movement outside the cell hence glucose molecules released in the blood. (I forgot to mention that it needed protein carriers and that it was passive - not requiring energy. Ah well hope I get the marks)

3c. Mitochondria the site of aerobic respiration - energy production. (32-34 ATP). I then went on to explain cellular respiration and how the mitochondria is needed for cells that require a constant supply of oxygen.

For 10 you might want to check Scooby's suggested answers! - 2014 VCE Biology Exam Solutions by Scooby

[stirfrynoodles]

I feel so relieved now that someone else answered question 3 the same way as I did. TBH I only learnt that secondary messenger thing like 5 days ago.

[Reus]

I feel so relieved now that someone else answered question 3 the same way as I did. TBH I only learnt that secondary messenger thing like 5 days ago.

Yeah, I just hope VCAA accepts varying answers cause it seems like their assessor's report is pretty standard.

[katiesaliba]

I'm just so worried about that experimental design question  I overthought it way too much. I included the elements necessary in those kind of questions, but my experiment was rather strange ahaha ahh 

[Reus]

I'm just so worried about that experimental design question  I overthought it way too much. I included the elements necessary in those kind of questions, but my experiment was rather strange ahaha ahh 

Yeah definitely. Especially when they gave half of the experiment and so we had to explain other factors ugh

[grannysmith]

Yeah sorry my bad! Had a lot of questions asking about it... I simply thought that the synthesised product (I forgot its name now) attaches to the allosteric region of the ATCase --> active site shape changes --> cannot properly bind to A and B substrate, production rate of D decreases as a result.

^ in simplified terms, of course.

Yeah this is exactly what I wrote, but I wasn't sure if we had to specify non/ competitive inhibition

[katiesaliba]

Yeah definitely. Especially when they gave half of the experiment and so we had to explain other factors ugh

That's what confused me so much! They had already performed the experiment so I was thinking what? ahh oh well, I think my experiment will at least be original :') 8 groups of identical cells...LOL.

[grannysmith]

That's what confused me so much! They had already performed the experiment so I was thinking what? ahh oh well, I think my experiment will at least be original :') 8 groups of identical cells...LOL.

20 groups here LOL

[katiesaliba]

20 groups here LOL

OMG! haha so glad I'm not the only one :') They should give us marks for originality 

[Litsy03]

Hey guys. For the question regarding number of nucleotides in mRNA strand to form 90 monomers, I wrote that one codon= one monomer. And I knew that they were trying to trick us, so I wrote +starting codon. However, I dont know what I was thinking but I accidentally wrote down the number of codons instead of the number of nucleotides. To make matters worse, I combined the number of codons (90) with the number of nucleotides in the starting codon 3. Considering I showed all working do you think I may still get one mark?

[infecthead]

Hey guys. For the question regarding number of nucleotides in mRNA strand to form 90 monomers, I wrote that one codon= one monomer. And I knew that they were trying to trick us, so I wrote +starting codon. However, I dont know what I was thinking but I accidentally wrote down the number of codons instead of the number of nucleotides. To make matters worse, I combined the number of codons (90) with the number of nucleotides in the starting codon 3. Considering I showed all working do you think I may still get one mark?

Tough to say, I think they'll give one mark for saying 270 nucleotides = 90 amino acids, and one mark for saying there would be 273 nucleotides total as you have to account for the stop codon, which doesn't code for an amino acid (the start codon does however, so that's part of the 90 amino acid chain).