VCE Biology Question Thread

[slothpomba]

my textbook was talking about the synapse being open or closed.. what does it mean if the synapse is open? just that neutral transmitters are being released from it? what does it mean if it's closed?

The synapse is not opened or closed, it is not something that can be opened or closed. It's a bit like saying my apple can be opened or closed, it's kind of nonsensical. It'd do you well to revise the definition and concept of a synapse.

what are the different types of chemical messages a cell may receive?

Attempt the question first and we will say if it is correct.

is the post synaptic membrane a part of another neurone that the electrical impulses  are being transferred to from one neuron?

Yes (simplistically, they are usually not electrical, may be a different kind of cell).

Is it the influx of calcium ions into the axon terminal that results in the release of neurotransmitters via exocytosis?

No. Revise your definitions for exocytosis and you'd see why'd this be impossible even on a definitional matter (regarding "influx" and "exocytosis").

[howlingwisdom]

Why does a receptor molecule undergo a conformation change when its ligand binds to it? (And does this only apply to receptors bound to the cell membrane or can it also occur with receptors in the cytoplasm of a target cell?)

[RazzMeTazz]

Do we need to know about radioactive isotopes and how these can be used in the medical field?

[vox nihili]

Do we need to know about radioactive isotopes and how these can be used in the medical field?

nope. Although they're pretty cool

[RazzMeTazz]

nope. Although they're pretty cool

 thanks yeah they are!

[RazzMeTazz]

Does anybody know around when does VCAA release the date of the biology exam?

And also, around what time was it last year?

[howlingwisdom]

Another question relating to signal transduction: I'm not entirely sure what would happen to the receptor molecule and the signal transduction pathway if the signal molecule is broken down?

[alchemy]

Does anybody know around when does VCAA release the date of the biology exam?

They publish the Exam Timetable for all written exams in May.

[rhinwarr]

When Na+ ions enter a neuron to trigger an action potential, do they enter by action transport or facilitated diffusion through the sodium channel?

[alondouek]

When Na+ ions enter a neuron to trigger an action potential, do they enter by action transport or facilitated diffusion through the sodium channel?

Facilitated diffusion through NaV (voltage-gated sodium channels) is the mode of sodium transport used in depolarisation.

[eagles]

I was wondering why there is always contamination of organelles in density gradient centrifugation but never in differential centrifugation?

Thanks for your help!

[RazzMeTazz]

Does the term 'denature' only refer to proteins or can it be used with other biomolecules as well?

Thanks 

[howlingwisdom]

Does the term 'denature' only refer to proteins or can it be used with other biomolecules as well?

Thanks 

I'm sure that 'denaturation' refers to only proteins (as the term refers to the breaking of weak bonds that hold the tertiary structure of a protein)

[slothpomba]

Why does a receptor molecule undergo a conformation change when its ligand binds to it? (And does this only apply to receptors bound to the cell membrane or can it also occur with receptors in the cytoplasm of a target cell?)

Why? I think the Why answer to that is honestly a bit beyond VCE, especially when they only teach you about enzymes in terms of lock and key. Where did you obtain the question?

If you mean why in different sense (functional), it changes in response to the ligand so that it can open (ion channels, etc)/perform the function activated by the ligand (other types). Think of it as a switch, it turns them "on" to do their function. If they were always on, they'd be kind of useless, so a switch is helpful.

If you mean why in a chemical/structural sense, i think its beyond VCE unless the curriculum has vastly changed.

When Na+ ions enter a neuron to trigger an action potential, do they enter by action transport or facilitated diffusion through the sodium channel?

Inside the cell is low in Na+, outside the cell is high in Na+, what does your knowledge of diffusion tell you about these things?

Na+ cant easily diffuse through the membrane because of its charge but the concentration gradient still exists for it to diffuse. The channel helps this process occur.

Another question relating to signal transduction: I'm not entirely sure what would happen to the receptor molecule and the signal transduction pathway if the signal molecule is broken down?

Depends when it is broken down, there is a proper time for it to be broken down for instance. If it is broken down when it isn't meant to be, the pathway will likely be impacted of course. If it's broken down very early, it'd be like the receptor molecule was never activated.

[RazzMeTazz]

I'm sure that 'denaturation' refers to only proteins (as the term refers to the breaking of weak bonds that hold the tertiary structure of a protein)

Oh okay thanks! So would you know if i had to include 'the breaking of weak bonds that hold the tertiary structure of a protein' in my definition of 'denaturation'?