VCE Biology Question Thread

[vox nihili]

What are the advantages of meiosis?

How does gene linkage affect the genotype of the offspring? (What is the impact of linkage on offspring?)

What is recombination and what are recombinants?

How do you justify whether a trait is dominant or recessive, looking at a pedigree chart?

In future try not to ask a heap of questions together and perhaps try to give them a shot yourself.

Meiosis generates genetic variation.

[Jason12]

I've also heard of self cross but is this just when you breed with yourself? (asexual reproduction?) So if you're a heterozygous Aa you just cross with Aa in a punnet square? Has this ever come up on a VCAA exam?

in a test cross for mice where B = black fur and b = white fur I crossed a BB and a Bb with homozygous recessive bb to find the genotype of the mouse but I end up with 2 punnet squares and 2 answers. So what do I write in the explanation since I have 2 alternatives or is there a way to find the correct answer?

[dankfrank420]

I think you're misunderstanding the point of the test cross Jason. You're not crossing two known genotypes with a homozygous recessive, you cross one unknown genotype with a homozygous recessive to find it's genotype.

For example, B = Brown and b = white

BB x bb = 100% Brown, therefore it can be inferred that the genotype of the unknown is BB
Bb x bb = 50% Brown, 50% white, therefore it can be inferred that the genotype of the unknown is Bb


Edit: @Trav- noted.

[vox nihili]

I've also heard of self cross but is this just when you breed with yourself? (asexual reproduction?) So if you're a heterozygous Aa you just cross with Aa in a punnet square? Has this ever come up on a VCAA exam?

in a test cross for mice where B = black fur and b = white fur I crossed a BB and a Bb with homozygous recessive bb to find the genotype of the mouse but I end up with 2 punnet squares and 2 answers. So what do I write in the explanation since I have 2 alternatives or is there a way to find the correct answer?

Self cross is when you self pollinate a plant or if an organism is a hermaphrodite or something. Humans can't do it, nor can most organisms

Edit: @Trav- noted.

Sounded a bit bitchy sorry, but it's just so you get an answer from people! I'll answer them in a tic.

[vox nihili]

What are the advantages of meiosis?

How does gene linkage affect the genotype of the offspring? (What is the impact of linkage on offspring?)

What is recombination and what are recombinants?

How do you justify whether a trait is dominant or recessive, looking at a pedigree chart?

As I mentioned, the major advantage of meiosis is that it generates genetic diversity. Meiosis really is the main driver of genetic variation in humans.

If two traits are linked, they're more likely to be seen together. So if you have one chromosome that's AB and the other is ab, it's more likely that the gamete will be AB or ab rather than Ab or aB.

Consult your textbook for recombination. It will have a better explanation than I can give, and with pictures (which you really need).

Recessive traits can skip generations, dominant traits can't.

[sandrag]

In how much depth are we required to know about the synthesis of biomacromolecules via the condensation reaction?

[vox nihili]

In how much depth are we required to know about the synthesis of biomacromolecules via the condensation reaction?

Water's produced.


That's it ^

[nhmn0301]

Has anyone got recommendations for some good practice exams? I've done some company one and see a few errors now and then (especially for BIO) I reckon checkpoint is the best but it would be great if you guys can recommend me some reputable companies or other resources? Thanks heaps !

[sandrag]

Water's produced.


That's it ^

Thankyou

[ravi2]

During what stage of meiosis does translocation occur?

[vox nihili]

Has anyone got recommendations for some good practice exams? I've done some company one and see a few errors now and then (especially for BIO) I reckon checkpoint is the best but it would be great if you guys can recommend me some reputable companies or other resources? Thanks heaps !

VCAA is the holy grail essentially.

[katiesaliba]

During PCR, what stops taq polymerase from synthesising a DNA molecule's complementary strand (elongation)? I understand that taq polymerase starts synthesising after the DNA primers, but when does it stop? Also, wouldn't some strands be longer than others, due to the DNA primer placement, and thus have differing sequences (at some points)?

[Shenz0r]

Has anyone got recommendations for some good practice exams? I've done some company one and see a few errors now and then (especially for BIO) I reckon checkpoint is the best but it would be great if you guys can recommend me some reputable companies or other resources? Thanks heaps !

NEAP, Insight, STAV. Checkpoint is just full of past VCAA exams which you can get off their site.

[dankfrank420]

As I mentioned, the major advantage of meiosis is that it generates genetic diversity. Meiosis really is the main driver of genetic variation in humans.

If two traits are linked, they're more likely to be seen together. So if you have one chromosome that's AB and the other is ab, it's more likely that the gamete will be AB or ab rather than Ab or aB.

Consult your textbook for recombination. It will have a better explanation than I can give, and with pictures (which you really need).

Recessive traits can skip generations, dominant traits can't.

Cheers! 

Sounded a bit bitchy

Don't worry about it mate

[vox nihili]

During PCR, what stops taq polymerase from synthesising a DNA molecule's complementary strand (elongation)? I understand that taq polymerase starts synthesising after the DNA primers, but when does it stop? Also, wouldn't some strands be longer than others, due to the DNA primer placement, and thus have differing sequences (at some points)?

Try to draw out a few cycles, putting the primers in the same spot. Assume that taq pol copies all the way to the end. Sure, I could explain it, but this is a nice one to nut out for yourself.