VCE Biology Question Thread

[anat0my]

Could someone please explain questions 13,16 & 18 of MC unit 3 2012? Thanks.

[dankfrank420]

Can anyone explain this question to me? The correct answer is B

It's a simple recall question, it shouldn't be too difficult if you know what a bottleneck is.

@anatomy

13 - So when the blood calcium level falls, it obviously needs to increase. A can't be correct, as this would result in even less blood calcium. Likewise for B. In the stem, it states that parathyroid hormone increases blood calcium level, so a reduction in its activity would mean even less blood calcium. Hence, answer cannot be C.

16 - Agglutination occurs if there are antigens present of the same blood type. Only option D has B blood being donated to blood with B antigens (don't let the AB throw you off). Therefore answer is D.

18 - A cannot be correct because baby shows no antibodies, hence mother cannot be immune to virus. B is not correct as antibodies given from mother tend to last a few months, so 2 years is too long. C cannot be correct as the question stem states that IgM antibodies cannot cross placenta, hence baby C cannot be given IgM antibodies from mum.

[anat0my]

Why is it said that memory B-cells are short-lived? I thought they 'long-lived'?

[vox nihili]

Why is it said that memory B-cells are short-lived? I thought they 'long-lived'?

yeah that wa sa bit vague. They do die eventually though

[AllG_]

VCAA Sample Exam question:
"A tissue that has been responsive to hormone X may, over time, lose its response to hormone X, even though the concentration of hormone X remain unchanged.
Based on your understanding of how a hormone controls the functioning of cells, suggest reasons for this decrease in responsiveness." (2 marks)

There aren't any solutions...could anyone help me out please?
Thanks

[grannysmith]

VCAA Sample Exam question:
"A tissue that has been responsive to hormone X may, over time, lose its response to hormone X, even though the concentration of hormone X remain unchanged.
Based on your understanding of how a hormone controls the functioning of cells, suggest reasons for this decrease in responsiveness." (2 marks)

There aren't any solutions...could anyone help me out please?
Thanks

Sample Exam questions are in reality just past VCAA questions. I remember this question, but forgot which year it's from.

It must be something to do with the receptors. I'd say something along the lines of: receptor sites for the hormone degrade over time, and become less effective in binding with the hormone.

[vox nihili]

It must be something to do with the receptors. I'd say something along the lines of: receptor sites for the hormone degrade over time, and become less effective in binding with the hormone.

VCAA Sample Exam question:
"A tissue that has been responsive to hormone X may, over time, lose its response to hormone X, even though the concentration of hormone X remain unchanged.
Based on your understanding of how a hormone controls the functioning of cells, suggest reasons for this decrease in responsiveness." (2 marks)

There aren't any solutions...could anyone help me out please?
Thanks

Surprised that that question came up on a VCAA exam. It is basically about receptors though. The cell takes away the receptors when they're stimulated too much, so there are less receptors to bind and therefore less response. As far as I know, this is actually what happens in type II diabetes. The insulin receptors are "recycled".

[mahler004]

Surprised that that question came up on a VCAA exam. It is basically about receptors though. The cell takes away the receptors when they're stimulated too much, so there are less receptors to bind and therefore less response. As far as I know, this is actually what happens in type II diabetes. The insulin receptors are "recycled".

In (early) type 2 diabeties, it's also thought that signalling transduction pathways may be altered/lost.

All the answers offered here are plausable.

[anat0my]

For question 5a. of Unit 4 2012, would 'prey' be an acceptable answer?

Also can someone please explain question 6a. of the same exam? Thanks!

[G3B]

What would be the survival advantage of having prominent brow ridges?
Also, would it be fine to say that more central Foramen magnum leads to better balance for upright walking? Or do we talk about having upright head when walking?
Thanks

[howlingwisdom]

A question about the Unit 4 2007 VCAA exam (question 1e) how can we tell that non-disjunction took place in Meiosis 2?

[Reus]

A question about the Unit 4 2007 VCAA exam (question 1e) how can we tell that non-disjunction took place in Meiosis 2?

Well of the failure of separation and segregation is in the sister chromatids then you know this must be in Meiosis II.

If it was the failure between homologous chromosomes then it'd be in Meiosis I

[melons]

Could someone please explain how you'd desensitize someone to an allergen?
Also, how you would treat an autoimmune disease by injecting antibodies? What do these antibodies attack?

[doomdestroyer]

Could someone please explain how you'd desensitize someone to an allergen?

You would give this person antihistamines which, is a drug that inhibits the action of histamine by blocking its attachment to histamine receptors, thus reducing the allergic response. I think this is how you would go about this.

[howlingwisdom]

Well of the failure of separation and segregation is in the sister chromatids then you know this must be in Meiosis II.

If it was the failure between homologous chromosomes then it'd be in Meiosis I

How was this evident in this question?