VCE Biology Question Thread

[kupus]

Yup! So most animal cells placed in hypotonic solutions are actually going to lyse (due to the absence of any cell wall to minimise how much the cell can stretch). However, some organisms like amoeba that live in fresh-water environments have actually evolved so that they use contractile vacuoles. These vacuoles contract and take up water so that it prevents the cell from expanding and lysing. Generally though, just know that placing animal cells in a hypotonic solution will inevitably lead to lysis of that cell.

Thanks heaps!

[isobelj]

just in case you have not seen the front cover

http://www.vcaa.vic.edu.au/Documents/exams/2016%20Nov%20exam%20covers/2016biology-cov-mc.pdf

ONLY 35 PAGES :/
usually 40+
might have a tonne of 1 markers.....

Wait, what does this mean?? Is it less likely that there will be longer questions or full page response questions (like those experiment ones)?

[Yacoubb]

Yup! So most animal cells placed in hypotonic solutions are actually going to lyse (due to the absence of any cell wall to minimise how much the cell can stretch). However, some organisms like amoeba that live in fresh-water environments have actually evolved so that they use contractile vacuoles. These vacuoles contract and take up water so that it prevents the cell from expanding and lysing. Generally though, just know that placing animal cells in a hypotonic solution will inevitably lead to lysis of that cell.

Thanks heaps!

No worries

Hi, thanks for your help
When you say if the parental chromosome 1 lined up to the left of equator and maternal chromosome 1 (I'm talking about the homologous pairs here) lined up on the left, do you mean one goes to the right and one to the left not both to the left? Still confused about it :/ Also, does it mean it is possible for gametes to have, let's say 75% maternal chromosomes and 25% paternal chromosomes- it's not always half from mum half from dad?

Recombination makes up for it so that you have 50% from each! The thing about independent assortment is that it is difficult to explain in words haha. The thing to remember is that one pair of homologous chromosomes will behave completely independent to another pair of homologous chromosomes in terms of how they line up, separate, etc. This enables somewhat randomised recombination -> leads to variation in gametes. I hope that is clarified

[larissaaa_]

Do both lipid-soluble hormones and water soluble ones cause signal transduction or do water soluble ones only activate a second messenger molecule and that is enough to produce a response?

[Springyboy]

Do both lipid-soluble hormones and water soluble ones cause signal transduction or do water soluble ones only activate a second messenger molecule and that is enough to produce a response?

They both eventually cause the target cell to carry out signal transduction.

However water soluble molecules activate secondary messengers (such as cAMP) to travel inside the cell and into the nucleus to cause signal transduction unlike lipid based molecules where the molecule themselves (such as steroids) travel directly into the nucleus to cause signal transduction.

[homosapien]

How does thyroxine have to ability to pass through the plasma membrane (and bind to receptor etc) and have lipid soluble characteristics if it is an amino acid derivative? Does something in the variable group allow it to pass?

[homosapien]

How do hydrophobic molecules e.g.lipids move around a cell / within cytosol?

[esthertham58]

It can. If you cross over once, everything from the cross-over point to the tip of the chromosome is exchanged. You have to cross over twice to get stuff in the middle like how we saw with C.

Yes, they're the same.

What one homologous chromosome does in anaphase, has nothing to do with what the other does; hence they assort independently. It probably should have been added that this also applies to non-homologous chromosomes too (as this is actually more important!).

Thanks!

[The Usual Student]

Wait, what does this mean?? Is it less likely that there will be longer questions or full page response questions (like those experiment ones)?

less likely to get very long questions, it could be
- a lot of 1-2 mark questions with very short stimulus
- a few BIG markers but hence less questions

But overall less pages means less to read hence it is way shorter and IMO a tad bit easier

[Angelx001]

Even though X and Y chromosomes have a large number of differing genes, there is a section of approximately 30 genes that is found on both the X and the Y chromosomes. This is known as the 'pesudo- autosomal region'. Explain what benefit this pseudo- autosomal region may have for the cell during meiosis?
Answer from LisaChem: "The pseudo-autosomal region on the sex chromosomes in humans allows the X and Y
chromosomes to form a partial homologous pair during prophase I of meiosis".

Is it possible for a man to pass on a Y chromosome that carries some of his mother's genes?
Answer: Yes, as crossing over can occur during prophase I of meiosis between these pseudo-autosomal regions of the sex chromosomes. Genes from the
pseudo-autosomal region of the X and Y chromosomes can exchange, resulting in a hybrid Y chromosome containing maternal genes.

Can someone explain this? And, X & Y chromosomes are non- homologous, so how can crossing over occur between them?

[vox nihili]

Even though X and Y chromosomes have a large number of differing genes, there is a section of approximately 30 genes that is found on both the X and the Y chromosomes. This is known as the 'pesudo- autosomal region'. Explain what benefit this pseudo- autosomal region may have for the cell during meiosis?
Answer from LisaChem: "The pseudo-autosomal region on the sex chromosomes in humans allows the X and Y
chromosomes to form a partial homologous pair during prophase I of meiosis".

Is it possible for a man to pass on a Y chromosome that carries some of his mother's genes?
Answer: Yes, as crossing over can occur during prophase I of meiosis between these pseudo-autosomal regions of the sex chromosomes. Genes from the
pseudo-autosomal region of the X and Y chromosomes can exchange, resulting in a hybrid Y chromosome containing maternal genes.

Can someone explain this? And, X & Y chromosomes are non- homologous, so how can crossing over occur between them?

You don't need to know any of this for VCE so don't worry about it.

[esthertham58]

Will we lose marks if we make spelling mistakes on the hominin species. Or is that not needed?

[AhNeon]

Will we lose marks if we make spelling mistakes on the hominin species. Or is that not needed?

As long as it's obvious you wont lose marks. Anyway the name would likely be in the stem of the question so just use that

[Angelx001]

Thanks vox nihili!!

Do some organisms obtain water from the water that is produced in aerobic respiration in the electron transport chain if they do not have any water available?

[larissaaa_]

Do we need to know the specifics of viruses and prions and bacteria and all that stuff? Like my textbook has all this detail on Gram stains and classifying bacteria but I'm really pushed for time so I don't want to be studying the wrong stuff. Also, anything else that's on the course for sacs and stuff but not for exams that I should be avoiding? Thanks.