VCE Biology Question Thread

[Hayley_turnham]

Hello
I was reading something in the frequently asked questions pdf for bio and in one section it says 'transduction for both lipid-based and protein-based signalling molecules involves a cascade of reactions that amplify the initial message...'.
now I thought that protein / amino acid / water soluble based hormones which bind to receptors on the membrane of the cell are the only type of hormones to result in a cascade or amplification effect as they require a second message. And lipid based hormones result in transcription of mRNA etc.
so I guess my question is what do they mean by a 'cascade of reactions' in relation to lipid based hormones, do they mean the same thing as a signal cascade from second messengers like in water soluble hormones and if so, how does this cascade effect work without 2nd messengers or do they just mean a series of events that occur after the hormone binds to the receptor in cytosol / nucleus such as the formation of mRNA
Sorry I dont know how to write down what I mean exactly aha but any help would be appreciated
Good luck with all the study xx

[HasibA]

For the inflammatory response, can we write mast cells release histamine which cause "vasodilation" thus attracting phagocytes to the site of infection etc..  Can i use the word "vasodilation"? Or do i have to write/Is it the same as writing: "...which cause 'arterioles to expand'.."

vasodilation is an appropriate term, should be g

Also, am i allowed to write MHC Class 1 markers or do i have to write Class 1 MHC markers? Would the examiners accept both?

should be fine either way

[hodang]

Thanks HASIBA!! BTW have any of you guys done a sac based on a research task on designer babies?

[HasibA]

Thanks HASIBA!! BTW have any of you guys done a sac based on a research task on designer babies?

yes-something similar. typically its the last sac for bio and its a very specific issue (personally, ours was to due with human intervention and such involved genes for cancers being patented etc.)
decent sac

[hodang]

Thanks once again HasibA! Youre a total legend! BTW do any of you guys have any free tickets to the atar lecture on Saturday for BIO?

[geminii]

Thanks once again HasibA! Youre a total legend! BTW do any of you guys have any free tickets to the atar lecture on Saturday for BIO?

I too need tickets for that! I PM'ed brenden but he is yet to reply...I suggest you PM brenden, and if he doesn't reply, come along anyway, i'll be there to snag any leftover seats!

[blacksanta62]

Hey guys, I just have some questions, any help would be appreciated
1) When explaining how negative feedback works and using blood glucose regulation as the specific example, am I allowed to say this (this is just a snippet of the answer)
"This stimulates the liver to convert glycogen into glucose and secrete it into the blood stream ==> Rise in blood glucose levels ==> Homeostasis achieved"
The part I'm worried about is in bold. The answer at the back of the book didn't comment on homeostasis being achieved
2) Could these be three major differences between nervous communication and hormonal communication
- Fast while hormonal communication requires time
- Large energy input while hormonal communication is passive (travel in the blood)
- Affects of nervous system are short lived while hormonal affects are prolonged
I didn't word them like this in my answer but this is the crux of the answer
Thank you

bump

[ezferns]

Hi everyone, sorry if this is a stupid question but how come water can pass through the cell membrane if it's polar?

[ezferns]

Hey guys, I just have some questions, any help would be appreciated
1) When explaining how negative feedback works and using blood glucose regulation as the specific example, am I allowed to say this (this is just a snippet of the answer)
"This stimulates the liver to convert glycogen into glucose and secrete it into the blood stream ==> Rise in blood glucose levels ==> Homeostasis achieved"
The part I'm worried about is in bold. The answer at the back of the book didn't comment on homeostasis being achieved
2) Could these be three major differences between nervous communication and hormonal communication
- Fast while hormonal communication requires time
- Large energy input while hormonal communication is passive (travel in the blood)
- Affects of nervous system are short lived while hormonal affects are prolonged
I didn't word them like this in my answer but this is the crux of the answer
Thank you

I'm pretty sure the rise in glucose stimulates the pancreas to release glucagon, which converts glycogen in the liver to glucose. So the pancreas is stimulated. And I don't think homeostasis is achieved immediately after, but after a couple of cycles with the pancreas slightly overshooting the amount of glucagon or insulin released each time.

I would change just one thing with the second question: change 'affects' to 'effects' as it's a noun. Not sure how picky the examiners will be with that

[sweetcheeks]

Hi everyone, sorry if this is a stupid question but how come water can pass through the cell membrane if it's polar?

Small polar molecules are capable of passing directly through the phospholipid bilayer. Water is small enough to be able to do so.

[blacksanta62]

I'm pretty sure the rise in glucose stimulates the pancreas to release glucagon, which converts glycogen in the liver to glucose. So the pancreas is stimulated. And I don't think homeostasis is achieved immediately after, but after a couple of cycles with the pancreas slightly overshooting the amount of glucagon or insulin released each time.

I would change just one thing with the second question: change 'affects' to 'effects' as it's a noun. Not sure how picky the examiners will be with that

1) Yeah, that's why I said it was a snippet. I did however mention that and other key players in glucose regulation in the whole answer
2) Okay
3) Will do, always get those two mixed up

[vox nihili]

I'm pretty sure the rise in glucose stimulates the pancreas to release glucagon, which converts glycogen in the liver to glucose. So the pancreas is stimulated. And I don't think homeostasis is achieved immediately after, but after a couple of cycles with the pancreas slightly overshooting the amount of glucagon or insulin released each time.

I would change just one thing with the second question: change 'affects' to 'effects' as it's a noun. Not sure how picky the examiners will be with that

Just gonna jump in here: a rise in glucose induces the release of insulin, which converts stops glycogen from being broken down. A FALL in glucose, on the other hand, induces the production of glucagon, which tells the liver to break down glycogen into glucose (among other things)

[blacksanta62]

I need to have a closer read of questions and answers. Thanks vox!

[blacksanta62]

Hey guys, I'm really having a hard time thinking of examples for the uses of GM foods and the benefits of GM foods. They seem like the same thing and my examples for uses are just explained/re-mentioned when listing benefits anyway. Can anyone suggest separate ideas for each?

Thank you

[HasibA]

Hey guys, I'm really having a hard time thinking of examples for the uses of GM foods and the benefits of GM foods. They seem like the same thing and my examples for uses are just explained/re-mentioned when listing benefits anyway. Can anyone suggest separate ideas for each?

Thank you

is a GM food referring to genetically modified food? i thought this wasn't examinable (unless it's a SAC)?
but anyways, some uses of genetically modified food could include loading them with vitamins and nutrients, allowing for a complementary benefit of giving a wide array of people access to food with many nutrients/fibres/vitamins- potentially reducing the cost/need to get multivitamins/medication to treat malnourished/deficient people? is this what u mean?