Biology Exam Chat + Exam Copy + Answers (now)

[cricketstar]

Hopefully they award marks for both nucleus and ribosome as that was such an ambiguous question.

[zoeee]

yeah i think it will be one of those questions where they award marks for both
the whole paper was very...  broad and the examiners are going to have a lot of fun reading because of the variety of answers that could have been given i reckon

[Namit]

bump:

Well technically RNA polymerase is found in ribosomes isnt it? Its an enzyme, therefore a protein, and ribosomes produce proteins? But ... transcription has to take place before that can happen so I guess the initial location of rna polymerase is the nucleus. Ambiguous but they should accept both..

Regarding question 3, "replacement of a defective allele with a normal allele... " , vcaa writes in the examiners report for 2008 :
"Gene therapy aims to insert a normal/functioning allele into a cell.
An example of incorrect information provided by students was ‘the removal of an allele or the insertion of an allele into
the body’. "

So Would 'DNA replacement' be correct?  Because they're saying that the for gene therapy, the removal of an allele is incorrect, and replacing involves removing.... ?

What do you think will be A+ cut off marks? 60/75?

[ggxoxo]

What would i need on this exam do you think after a 65ish/75 midyear, and an 85% average on sacs, to get a 45+?

I think as a general rule 3 A+s on all GAs yields about 40 (this is just what I've been told!)

[cricketstar]

What would i need on this exam do you think after a 65ish/75 midyear, and an 85% average on sacs, to get a 45+?

75, just to be sure

[TheEscapist]

I have also been racking my brains over something with the dog phenotype question.
Suggested solutions say that parents are BbTt and bbtt. (2ciii)
But in the previous question (2cii) say the dogs can have different genotypes if black with white spots (Bbtt and BBtt).
If BbTt and bbtt are crossed, the only possible genotype for the dog with phenotype P is Bbtt though.
Possible vcaa would take off marks if you said they could have different genotypes, but later said parents were BbTt and bbtt?

[Panicmode]

I have also been racking my brains over something with the dog phenotype question.
Suggested solutions say that parents are BbTt and bbtt. (2ciii)
But in the previous question (2cii) say the dogs can have different genotypes if black with white spots (Bbtt and BBtt).
If BbTt and bbtt are crossed, the only possible genotype for the dog with phenotype P is Bbtt though.
Possible vcaa would take off marks if you said they could have different genotypes, but later said parents were BbTt and bbtt?

That is true... I wrote (just to be sure) all possible genotypes for the parents:

Parent 1:
BbTt

Parent 2:
BbTt, bbtt, Bbtt, bbTt

[lexitu]

^ Yes, but the question said "all pups" with that phenotype - not necessarily the one in the scenario. VCAA would almost definitely not take marks off as the question (2ciii) asks what the genotypes of the parent dogs are, not the potential genotypes. So you didn't need to give all options, although I think it's okay if you did.

[Namit]

Wouldn't BbTt x BbTt imply a 9:3:3:1 ratio ? The question said a litter of 4, so I don't think they'll accept BbTt for both parents, or will they?

[Panicmode]

Wouldn't BbTt x BbTt imply a 9:3:3:1 ratio ? The question said a litter of 4, so I don't think they'll accept BbTt for both parents, or will they?

Yes, but a litter of four isn't exactly sufficent sample space. If they had say 100 pups and 23 were black with no white, 26 where black with no white, 24 were grey with no white and 27 were grey with white. Then sure, only accept BbTt x bbtt as the genotype but with only four, it is incredibly ambiguous.

[lexitu]

^ Yes it would, but being only a litter of four means yes it's slightly more likely to be BbTt x bbtt but this isn't a grand experiment with 100 dogs so they should accept all. It's not like they said most likely either - you should always go with that option though.

[TheEscapist]

Surely 4 pups isn't enough for us to assume its a 1:1:1:1 ratio. Hopefully vcaa gives marks for both answers.
I also hope they give marks for protein sequencing and nuclear dna in question 7. Would make my year.

[Namit]

Hopefully they accept BbTt and BbTt for both parents...!

[LukeMcA]

Mm, I had BbTt x BbTt as well..

[pezz619]

also, for the DNA apart from mtDNA, did you have to specify a particular part of nuclear DNA??
Like Y chromosome or hypervariable regions??
not sure if i did