VCE Biology Question Thread

[Shax]

Do plants also have positive and negative feedback mechanisms?!!!

[Apink!]

Hi,
I'm really confused about the immunity section.
So, dendritic cells and macrophages are on the 'look out' for these pathogens in the body. And when they meet one, they bind to the antigens and release cytokines to let other white blood cells know. But are dendritic cells and macrophages also able to engulf these pathogens themselves? Or are they just acting as messengers for other cells like neutrophils and monocytes to kill them?

[Apink!]

Can I ask another question?
Do T cells have MHC class I or II markers on them? I know they can recognize them, but do they have them?

[HasibA]

I've got a 'glucose regulation' sac coming up and was wondering what questions would be likely to be on it? thank you
any help is appreciated

[Maddie Trinh]

Hi guys, this is a pretty confusing question for myself this time, or maybe it was just how I approached it XD
My teacher said signal amplification can refer to the series of reactions triggered in the cell after the binding of the hormone to the receptor whereas signal transduction refers to the whole entire process of receiving the signal, transducting the signal etc. Therefore is signal amplification the same as the cascade of events which occur as the signal is converted to another kind or is a cascade of events produced from signal amplification?

thanks in advance to anybody who can help 

[geminii]

Hi guys, this is a pretty confusing question for myself this time, or maybe it was just how I approached it XD
My teacher said signal amplification can refer to the series of reactions triggered in the cell after the binding of the hormone to the receptor whereas signal transduction refers to the whole entire process of receiving the signal, transducting the signal etc. Therefore is signal amplification the same as the cascade of events which occur as the signal is converted to another kind or is a cascade of events produced from signal amplification?

thanks in advance to anybody who can help 

I'm pretty sure that signal amplification results in a cascade of events - like when the secondary messengers trigger more than one molecule, that is signal amplification, but as each secondary messenger triggers more and more secondary messengers, that is when it is a cascade of events. Then again I'm not sure if that 'cascading of events' is called 'signal amplification' itself, or if it is what causes the cascade, which is what I'm pretty sure you're asking! Anyone feel free to elaborate because I definitely don't have the full picture either!

[vox nihili]

Hi,
I'm really confused about the immunity section.
So, dendritic cells and macrophages are on the 'look out' for these pathogens in the body. And when they meet one, they bind to the antigens and release cytokines to let other white blood cells know. But are dendritic cells and macrophages also able to engulf these pathogens themselves? Or are they just acting as messengers for other cells like neutrophils and monocytes to kill them?

Dendritic cells/macrophages can both engulf pathogens. Macrophages do the bulk of "eating up" of pathogens as it were, whereas dendritic cells only really do it so as to signal to the immune system that a pathogen is there.
Also, remember that monocytes are just macrophages living in the blood. So they're effectively the same thing.

Can I ask another question?
Do T cells have MHC class I or II markers on them? I know they can recognize them, but do they have them?

They class I. All nucleated cells have class I molecules. All antigen presenting cells (dendritic cells, B-cells) have class II

I've got a 'glucose regulation' sac coming up and was wondering what questions would be likely to be on it? thank you
any help is appreciated

Try to have a guess yourself and post here Really good exercise imo

Hi guys, this is a pretty confusing question for myself this time, or maybe it was just how I approached it XD
My teacher said signal amplification can refer to the series of reactions triggered in the cell after the binding of the hormone to the receptor whereas signal transduction refers to the whole entire process of receiving the signal, transducting the signal etc. Therefore is signal amplification the same as the cascade of events which occur as the signal is converted to another kind or is a cascade of events produced from signal amplification?

thanks in advance to anybody who can help 

The cascade of events includes the amplifcation of the signal. So you can receive the signal, activate a few proteins one by one and then eventually activate a protein that activates a whole heap of proteins, which is the amplification.

E.g. receptor activates protein A, protein A then activates protein B, protein B activates C, and then protein C activates 400 protein Ds

Only the last step is the amplification, because all of the antecedents occur in a 1:1 ratio (i.e. one molecule of protein A activates only one molecule of protein B)

Do plants also have positive and negative feedback mechanisms?!!!

Yes

[Ameliajanem]

We've just started area of study 2, and i have the heinemann textbook and I am struggling so much with it's explanations and the way it's worded, I want to cry just reading it. My teacher is usually happy to explain things to me but i honestly don't want to have to ask for detailed explanations for every one of the 20 or so chapters, so i was wondering if it would be worth me getting a copy of the Nature of Biology because apparantly that's better?

[Elizawei]

We've just started area of study 2, and i have the heinemann textbook and I am struggling so much with it's explanations and the way it's worded, I want to cry just reading it. My teacher is usually happy to explain things to me but i honestly don't want to have to ask for detailed explanations for every one of the 20 or so chapters, so i was wondering if it would be worth me getting a copy of the Nature of Biology because apparantly that's better?

It is considered as a "more detailed" textbook, and has more extra content outside the VCE course.
My school used Nelson, but my teacher gave us a pdf version of the Nature of Biology anyway for extra reading (ended up not using it at all  )

MOD EDIT: don't share copyrighted material please

EDIT: oops sorry didn't realise 
Thanks for edit 

[vox nihili]

We've just started area of study 2, and i have the heinemann textbook and I am struggling so much with it's explanations and the way it's worded, I want to cry just reading it. My teacher is usually happy to explain things to me but i honestly don't want to have to ask for detailed explanations for every one of the 20 or so chapters, so i was wondering if it would be worth me getting a copy of the Nature of Biology because apparantly that's better?

Don't forget that there are lots of great resources on the internet just a Google away. The biology you learn in VCE is pretty well the same all around the world, so there's a tonne of stuff.

I agree about Heinemann being a bad textbook though. It has the whole "I want to show off" feel to it if truth be told.

[mtDNA]

Would a feasible definition for signal transduction be:
The cascade of events linking an external signal, such as a hormone, to a specific cellular response.

Thanks 

[vox nihili]

Would a feasible definition for signal transduction be:
The cascade of events linking an external signal, such as a hormone, to a specific cellular response.

Thanks 

Yes

[geminii]

For phospholipids, is this correct to say?
"The phosphate group is negatively charged/polar/hydrophilic (the negative charge makes this end polar and hence hydrophilic)"

I'm getting confused by my own notes!

[Syndicate]

For phospholipids, is this correct to say?
"The phosphate group is negatively charged/polar/hydrophilic (the negative charge makes this end polar and hence hydrophilic)"

I'm getting confused by my own notes!

Yep. Phosphate groups are polar due to their negative charge.

[Gogo14]

In an experiment, where trypsin is used to hydrolyse casein(protein in milk) to turn the milk clear, why is using milk powder better than using plain milk?Pls respond, urgent thnx