VCE Biology Question Thread

[zxcvbnm18]

I need some clarification..
So only healthy,self hla markers can bind to killer inhibtory receptors on nk cells and block the kill signal right?
And also are both the killer activating receptors and killer inhibitory receptors specific?
Thnx for the help!

[zxcvbnm18]

Why is the MAC attack ineffective against gram positive bacteria?

Thnx in advance

[Quantum44]

Why is the MAC attack ineffective against gram positive bacteria?

Thnx in advance

The gram-positive bacteria have a thick peptidoglycan layer covering the cell membrane which prevents complement proteins from binding on the plasma membrane and causing the bacterial cell to lyse.

I need some clarification..
So only healthy,self hla markers can bind to killer inhibtory receptors on nk cells and block the kill signal right?
And also are both the killer activating receptors and killer inhibitory receptors specific?
Thnx for the help!

I believe only healthy, self MHC-1 receptors can inhibit NK cells. Activating and inhibitory receptors are specific for NK cells.

[vox nihili]

I need some clarification..
So only healthy,self hla markers can bind to killer inhibtory receptors on nk cells and block the kill signal right?
And also are both the killer activating receptors and killer inhibitory receptors specific?
Thnx for the help!

This is well beyond the course, you don't need to know about it.

Why is the MAC attack ineffective against gram positive bacteria?

Thnx in advance

This is also well beyond the course!

[chany23]

Is handsanitiser bacteriostatic or bactericidal and please explain why??
Thanks for the help in advance!

[simrat99]

Is it incorrect to say that RNA polymerase catalyses the production of mRNA?

[TheAspiringDoc]

Is it incorrect to say that RNA polymerase catalyses the production of mRNA?

I wouldn't think it would be incorrect. I.e. It's actually true. Because aids the synthesis of an mRNA transcript during transcription, and it is an enzyme (recall that enzymes are defined as protein CATALYSTS)
Is there any other reason why you were thinking that?

[vox nihili]

Is handsanitiser bacteriostatic or bactericidal and please explain why??
Thanks for the help in advance!

Beyond the course.

It would have to be bactericidal though, otherwise it'd be effectively useless.

[captkirk]

For the scientific poster we are supposed to design a poster

This may sound stupid but
How can you design an experiment to measure the rate of photosynthesis in incandescent, halogen, fluorescent and black lights.

[Quantum44]

For the scientific poster we are supposed to design a poster

This may sound stupid but
How can you design an experiment to measure the rate of photosynthesis in incandescent, halogen, fluorescent and black lights.

Well if you want to measure the rate of photosynthesis, you need to think about what photosynthesis actually produces or uses. In this case, the most obvious is carbon dioxide and oxygen. So I'd recommend measuring via uptake of carbon dioxide or production of oxygen. Although in no light, the opposite occurs, so the easiest way is to measure the change in pH when you add a hydrogen carbonate indicator, which changes colour as carbon dioxide concentration changes.

Therefore, when there is more photosynthesis, less carbon dioxide is produced, which means less is reacted to form carbonic acid, so the pH increases and the indicator turns purple.

[captkirk]

Well if you want to measure the rate of photosynthesis, you need to think about what photosynthesis actually produces or uses. In this case, the most obvious is carbon dioxide and oxygen. So I'd recommend measuring via uptake of carbon dioxide or production of oxygen. Although in no light, the opposite occurs, so the easiest way is to measure the change in pH when you add a hydrogen carbonate indicator, which changes colour as carbon dioxide concentration changes.

Therefore, when there is more photosynthesis, less carbon dioxide is produced, which means less is reacted to form carbonic acid, so the pH increases and the indicator turns purple.

Thank you for the great answer!
Any ideas about what I could write about the methodology?

[Quantum44]

Thank you for the great answer!
Any ideas about what I could write about the methodology?

The main thing you have to be aware of is when cellular respiration or photosynthesis is happening at a faster rate, which depends on the amount of sunlight and is characteristic of a change in pH.

Low pH = More respiration compared to photosynthesis
High pH = More photosynthesis compared to respiration

Don't forget your comparative statements, you can't just say there is more of something without explicitly comparing it to something else.

[simrat99]

Hi,
With questions related to the sequence of events in translation and transcription and that are around 3-4 marks, what kind of details does VCAA want us to include?
Thanks in advance

[vox nihili]

Hi,
With questions related to the sequence of events in translation and transcription and that are around 3-4 marks, what kind of details does VCAA want us to include?
Thanks in advance

Perhaps look at the examiner's report? There were questions on both these things unit 4 2012 Not trying to fob you off or anything, you'll just get more reliable information straight from the horse's mouth than from us

[Quantum44]

Hi,
With questions related to the sequence of events in translation and transcription and that are around 3-4 marks, what kind of details does VCAA want us to include?
Thanks in advance

You don't need a lot of detail.

For example there was a translation question on the 2016 exam and all you needed to say was:

- tRNA has a specific amino acid
- carries amino acid to ribosome
- tRNA anticodon attaches to mRNA codon
- then amino acids are joined

Source: http://www.vcaa.vic.edu.au/Documents/exams/biology/2016/biology_examrep16.pdf