VCE Biology Question Thread

[grannysmith]

If it is indeed X linked, then you'd still be correct as you're only being more (accurately) specific.
You'd only lose marks if you said it was Y linked.

[grannysmith]

According to the study design, we have to know
The nature of genomes, genes and the genetic code. What exactly is this asking us to know?

What a genome is; 2 alleles at each gene locus; functions of genes; triplets, codons, anti codons; properties of DNA (universal, redundant etc.).

This is just off the top of my head and definitely not an exhaustive list. If anyone else can add anything...?

[dankfrank420]

Is there a distinction between when DNA is universal and when DNA is redundant?

[Stew_822]

Not sure what you're asking above, but I think DNA is referred to as universal because the same base sequence codes for the same amino acids in almost all organisms. It's referred to as redundant because the same amino acid can be specified by more than one codon (a codon is a sequence of three bases).

Hope that helps you.

In the 2011 exam 1:
http://www.vcaa.vic.edu.au/Documents/exams/biology/2011biology1-w.pdf

The multiple choice questions 24 and 25 are really stupid. The answers listed are C for Q24 and B for Q25. First of all I'm wondering how we figure out which person has a specific antibody in their system? I don't quite understand the question, are they putting antibodies to the viruses in the people's systems? If so, the people who have already had the virus would have antibodies in their systems and the addition of these antibodies would make no difference, and hence no agglutation. If the people have no antibodies in their system, there would only be agglutation if the person was currently infected - and the question clearly states that they're trying to work out if they've already been infected, not whether they're currently infected (which you would imagine they would know because they'd be sick.)

So that's my first problem. My second one is that the answer to Q24 is C, which means that VCAA believe it is "reasonable to infer from the information in the table" that Emily has had the greatest number of different viruses. If the table contained all of the viruses in the world, sure, you could infer that, but we have no idea what other kinds of viruses these people have been exposed to, so that is a totally unreasonable answer. It was the first one I discounted because it was so stupid. B and D were obviously wrong, so that left me with A, which makes sense because the addition of the same antibodies wouldn't produce agglutation and really I just had to assume all of the other people who produced agglutation were currently infected with the virus and thus had the antigens in their system, which would react with the antibodies.

The whole question doesn't make sense. Why would they be giving antibodies to people for the specific viruses? You'd think they'd be giving them the antigens and seeing if that caused agglutation. I figure by "Antibody to" VCAA actually mean "Antigen of". Is that right?

If I'm right then VCAA is retarded because that's a pretty monumental f#$kup and I don't want my work to be assessed by them.

[anat0my]

Are we required to provide this depth of knowledge?
 
Q. Explain how altering the pH of a solution can alter the function of a plasma membrane?

If a solution becomes too basic the plasma membrane is destroyed because it is composed of lipids with
disintegrate in strong bases (think of oil in water when detergent is added) [1]
If a solution becomes too acidic protein channels in the plasma membrane can be denatured meaning
gaps can be formed in the membrane and selective passage of molecules across the membrane cannot
occur. [1]

^That's the suggested solution.
Can it be sufficient to say that a pH that deviates from the optimal range of the proteins in the plasma membrane will cause the proteins to denature and thus cease to function. ?? Thanks!

[vox nihili]

Are we required to provide this depth of knowledge?
 
Q. Explain how altering the pH of a solution can alter the function of a plasma membrane?

If a solution becomes too basic the plasma membrane is destroyed because it is composed of lipids with
disintegrate in strong bases (think of oil in water when detergent is added) [1]
If a solution becomes too acidic protein channels in the plasma membrane can be denatured meaning
gaps can be formed in the membrane and selective passage of molecules across the membrane cannot
occur. [1]

^That's the suggested solution.
Can it be sufficient to say that a pH that deviates from the optimal range of the proteins in the plasma membrane will cause the proteins to denature and thus cease to function. ?? Thanks!

pH disrupts the phospholipid bilayer
pH may denature the proteins

That's all you need to know

[Rachelle]

What is the difference between ATP synthase and ATPase and the functions of each?
Also, what is a compensation pt?

[vox nihili]

What is the difference between ATP synthase and ATPase and the functions of each?
Also, what is a compensation pt?

ATP synthase makes ATP, an ATPase converts ATP to ADP

[Scrono13]

What are the major trends in hominin evolution from the genus Australopithecus to the genus Homo including morphological, structural and cognitive development resulting in cultural evolution and the rise of technologies?

[vox nihili]

What are the major trends in hominin evolution from the genus Australopithecus to the genus Homo including morphological, structural and cognitive development resulting in cultural evolution and the rise of technologies?

Perhaps you'd like to suggest some answers first?

[grannysmith]

Also, what is a compensation pt?

Edit: the light intensity which results in the rate of carbon dioxide consumption equalling the rate of carbon dioxide production in plants; that is, when rate of cellular respiration = rate of photosynthesis.

[grannysmith]

A question asks to describe two situations where terrestrial fossilisation can occur.

My answer: In low oxygen level (anoxic) environments and when the specimen is quickly buried by sediment, to prevent decay.

The suggested answers: ice can freeze organisms; volcanic ash can bury organism; sap can trap organism to become amber; any other suitable answer.

Would my answer still be valid?

[katiesaliba]

For this question, would answering with 'dendritic cells and macrophages' be considered correct? 

[Reus]

For this question, would answering with 'dendritic cells and macrophages' be considered correct?

I would say so.

[katiesaliba]

Don't complement proteins assist in innate defence by lysing pathogens and encouraging opsonisation, etc. Isn't this their role rather than assisting in blood clotting?

Steroid hormones don't require a second messenger because they're lipophilic and thus diffuse directly across cellular membranes. Relay molecules (a cascade of enzymes) within the cytosol of the cell facilitate the transduction and amplification of the message. This is correct, right?