VCE Biology Question Thread

[Gogo14]

Look up the definitions of a nonsense mutation, missense mutation, and silent mutation. The ans you circled is a missense, not nonsense mutation

The answer I circled is in blue,still can't see the error after googling.....

[hodang]

Can someone please answer these questions for me, would be highly appreciative

Are mast cells specific or non-specific?

Why are memory cells short lived?

For induction, (in signal transduction) do we have to include transcription and translation?

On the 2010 biol exam 1 q2(b)  can my hypothesis be the opposite to the one indicated in the vcaa answers? Can I write nice that war soft pellets will weigh more than hard pellets? Can my hypothesis differ? But rest of exp is like the same?

Do Homo sapiens have a short, wide pelvis or a more narrow pelvis?

Can we say Smaller brain case or do we have to say smaller craniel capacity?

Is gene pool the total number of alleles "present in an interbreeding population at a given time"

ACG GCA
What is the second codon in this sequence? is it "GCA" or is it "C" in ACG?

[drepwns]

For question 3ei and ii on VCAA Unit 4 2010,

3ei) What is the chance that a sperm from the man will contain a normal chromosome 1 and a normal chromosome 2?

3eii) Outline your reasoning.

I did end up getting the question correct, but my thought process made absolutely no sense as I thought back to it, if anyone could help - it would greatly be appreciated!

[hodang]

I'm pretty sure that it is 25% because there's a 1/2 chance of receiving a boy, and a 1/2 chance of it being unaffected, so 1/2 X 1/2 = 1/4 (25%) This is only if it's an X-linked trait,

However I'm pretty sure if it were too be Autosomal, it would be a 50% chance

Can someone please confirm this? Because I've done similar questions and this is how they've done it. Thanks

Can anyone confirm this please urgently?

[Butterflygirl]

1. Really stumped with the mc in the question attached
2. How do you do the questions that give you a number of alleles and ask for the possible number of phenotypes and genotypes. I always get these wrong. Is there some trick, other than doing  a massive punnet square?

For question 1, how do we know that the male and female seeking the counselling are heterozygous? because I thought they could be either heterozygous or homozygous dominant because each of their parents must be both heterozygous?

I don't know, I've been this question before and I'm still confused.

Help is appreciated

[drepwns]

Since this is an X linked trait (X^H, indicating that the trait is determined by the X chromosome) it would be reasonable to conclude that the mother (kate) would also have the trait since she is the one in charge of giving her sons the X chromosome and the father gives the Y (as im sure u know). However im not quite sure why you cant say elliot cant have the trait, maybe because its more reasonable to say the mother has it?
Hope i helped a little 

I reckon this is just a poorly written question, and in this case - being that mitochondrial traits are X-linked dominant, to ensure that all offspring inherit trait, the mother possesses a homozygous dominant genotype for the trait, hence implying that all offspring including herself would possess a X^H allele, so I believe there are 2 answers to that question.

[asini_s]

Can someone please answer these questions for me, would be highly appreciative

Are mast cells specific or non-specific?

Why are memory cells short lived?

For induction, (in signal transduction) do we have to include transcription and translation?

On the 2010 biol exam 1 q2(b)  can my hypothesis be the opposite to the one indicated in the vcaa answers? Can I write nice that war soft pellets will weigh more than hard pellets? Can my hypothesis differ? But rest of exp is like the same?

Do Homo sapiens have a short, wide pelvis or a more narrow pelvis?

Can we say Smaller brain case or do we have to say smaller craniel capacity?

Is gene pool the total number of alleles "present in an interbreeding population at a given time"

ACG GCA
What is the second codon in this sequence? is it "GCA" or is it "C" in ACG?

I think these are the answers haha 
1)mast cells have specific antibodies attached to them
2) memory cells aren't short lived, antibodies are
3) not sure, but in past vcaa questions they haven't mentioned it
5) narrow pelvis
6) depends on the question
7) total sum of alleles  in a population at a given time
8 ) GCA as its the second triplet codon

[AhNeon]

Can someone please answer these questions for me, would be highly appreciative

Are mast cells specific or non-specific?

Why are memory cells short lived?

For induction, (in signal transduction) do we have to include transcription and translation?

On the 2010 biol exam 1 q2(b)  can my hypothesis be the opposite to the one indicated in the vcaa answers? Can I write nice that war soft pellets will weigh more than hard pellets? Can my hypothesis differ? But rest of exp is like the same?

Do Homo sapiens have a short, wide pelvis or a more narrow pelvis?

Can we say Smaller brain case or do we have to say smaller craniel capacity?

Is gene pool the total number of alleles "present in an interbreeding population at a given time"

ACG GCA
What is the second codon in this sequence? is it "GCA" or is it "C" in ACG?

Mast cells are part of second line of defence-non specific
Well they're not that short lived, but they can start to break down. This is what a booster shot is for
I dont see how transcription and translation are relevant unless it's a steroid hormone which 'turns on' a gene. But even then you shouldnt need to talk about the actual expression in depth unless the question asks for it
I dont know, mine was the opposite as well.
Dont know
I guess either should do as the both point to the fact that a smaller brain case/cranial capacity is likely an indicator of a smaller brain size
I dont think you have to mention 'interbreeding' here. Actually, i think it detracts from its meaning
Codons are basically 3 nucleotides, so its GCA

[Butterflygirl]

Sorry for repeating but can someone please explain this question:

Q: A couple seek a genetic counsellor's advice about their chances of having a child with the autosomal recessive condition of Tay Sachs disease. Both the female and the male have a sibling with Tay Sachs but no other family members have the disease. The advice would be that the probability of their child having Tay Sachs would be?

I don't understand why the answer is 1/9 because the male and female could be homozygous dominant or heterozygous.

Help is appreciated

[mayonnaise]

The answer I circled is in blue,still can't see the error after googling.....

Woops sorry! For some reason I thought you were the red 
Yeah I'd say your answer is right then the test must have made a mistake

[AhNeon]

would this suffice for the function of rough ER: holds ribosomes which are the site of protein synthesis. It then transports these proteins to golgi body

[FatimaEl]

would this suffice for the function of rough ER: holds ribosomes which are the site of protein synthesis. It then transports these proteins to golgi body

Sounds good to me!

[AhNeon]

Thanks, also for question 7)c) on 2015 exam (question attached) the answer seems very broad or something and im not sure if my answer would be accepted.
My answer was:
-Different GC specific receptors present in rat pituitary gland cell and liver cells
-GC hormone binds to different specific receptors
-different receptors bind to different operator regions on DNA, initiating transcription and expression of different genes that code for different proteins
-The protein produced in pituitary gland is a growth hormone while in the liver it is the enzyme tryptophan oxygenase

[plsbegentle]

Sorry for repeating but can someone please explain this question:

Q: A couple seek a genetic counsellor's advice about their chances of having a child with the autosomal recessive condition of Tay Sachs disease. Both the female and the male have a sibling with Tay Sachs but no other family members have the disease. The advice would be that the probability of their child having Tay Sachs would be?

I don't understand why the answer is 1/9 because the male and female could be homozygous dominant or heterozygous.

Help is appreciated

so the parents of the female and male must be carriers(Aa,Aa) since they don't have the trait but they have affected children. the two unaffected male and female have a 2/3 chance of also being carriers. (AA,Aa,Aa, excluding aa).So the probability that they are both hetrerozygous is  2/3 x 2/3= 4/9 The probability of having an affected child overall is 1/4.
 4/9 x 1/4 is 4/36 which is 1/9.

Thanks, also for question 7)c) on 2015 exam (question attached) the answer seems very broad or something and im not sure if my answer would be accepted.
My answer was:
-Different GC specific receptors present in rat pituitary gland cell and liver cells
-GC hormone binds to different specific receptors
-different receptors bind to different operator regions on DNA, initiating transcription and expression of different genes that code for different proteins
-The protein produced in pituitary gland is a growth hormone while in the liver it is the enzyme tryptophan oxygenase

sure, the different receptors part is correct but the genetic sequence is identical in the rat cell, as stated in the question so your 3 dot point is wrong i guess. also receptors don't bind to operator regions. if i remember correctly, regulator genes was the correct answer. But my tutor said that different receptors leading to different biological pathways.

[vox nihili]

Thanks, also for question 7)c) on 2015 exam (question attached) the answer seems very broad or something and im not sure if my answer would be accepted.
My answer was:
-Different GC specific receptors present in rat pituitary gland cell and liver cells
-GC hormone binds to different specific receptors
-different receptors bind to different operator regions on DNA, initiating transcription and expression of different genes that code for different proteins
-The protein produced in pituitary gland is a growth hormone while in the liver it is the enzyme tryptophan oxygenase

Your answer is actually completely plausible and biologically correct. The answer given in the examiner's report, imo, was a pretty poor answer and failed to demonstrate an understanding of the question (remember the Chief Examiner isn't the person who writes the exam!).

What VCAA seems to be implying is that in different cells GC induces different regulator proteins, and these different regulators are then responsible for the production of the two different proteins described in the question. Of course, you could very correctly counter that it makes absolutely no sense that GC would induce the production of different regulators, and you'd be absolutely right.

With that said, this is in the study design:

the concept of gene regulation (the switching on and off of genes by factors expressed by
regulator genes and environmental factors)

In reality, I think your answer is biologically plausible and a reasonable answer for the VCE course. My knowledge of glucocorticoid certainly isn't expansive, but I think that your answer is actually fairly close to the truth of why you see different responses to glucocorticoid in different tissues.