VCE Biology Question Thread

[Frozone]

The question is hope does a nerve impulse pass from one cell to the next?
I wrote "through neurotransmitters located at the synaptic gap". Is that right, because the book gives me an extremely long answer.

Thanks in advance!

[Reus]

What would be the impact of a tumour in the pituitary gland (normal production of TSH is inhibited) cause on the metabolic rate of body cells?

[vox nihili]

What would be the impact of a tumour in the pituitary gland (normal production of TSH is inhibited) cause on the metabolic rate of body cells?

metabolic rate goes down. TSH is thyroid stimulating hormone, less thyroxine is produced etc etc

[Frozone]

What is the role of receptors and effectors in the plant response?

[Reus]

What is the role of receptors and effectors in the plant response?

A receptor is a structure which receives something, while an effector carries out a task. For example the photo receptors in the eyes receive photons of light. Stretch receptors in the muscles detect the amount of stretch in those muscles. In both these cases the receptors are neural and so the response is to fire an action potential. You can also have hormonal receptors eg glucose receptors on your islet cells in the pancreas.

The effectors are the organs which respond to the signals generally triggered by these receptors. eg when you hit your knee with a reflex hammer the stretch receptors in your quadraceps muscles detect the stretch, fire an action potential (the signal) to your spinal cord, where they synapse with motor neurons which run back to the stretched muscle, causing it to contract. In this case the effector is the quadriceps muscle since it is the thing that carries out the function triggered by the signal.

In the case of high blood glucose the receptors are glucose receptors on your beta islet cells in your pancreas, which then produce the signal (insulin). Body cells such as muscle cells or liver cells would be the effectors as they then receive the signal and act on it, ie absorb glucose.

[Frozone]

A receptor is a structure which receives something, while an effector carries out a task. For example the photo receptors in the eyes receive photons of light. Stretch receptors in the muscles detect the amount of stretch in those muscles. In both these cases the receptors are neural and so the response is to fire an action potential. You can also have hormonal receptors eg glucose receptors on your islet cells in the pancreas.

The effectors are the organs which respond to the signals generally triggered by these receptors. eg when you hit your knee with a reflex hammer the stretch receptors in your quadraceps muscles detect the stretch, fire an action potential (the signal) to your spinal cord, where they synapse with motor neurons which run back to the stretched muscle, causing it to contract. In this case the effector is the quadriceps muscle since it is the thing that carries out the function triggered by the signal.

In the case of high blood glucose the receptors are glucose receptors on your beta islet cells in your pancreas, which then produce the signal (insulin). Body cells such as muscle cells or liver cells would be the effectors as they then receive the signal and act on it, ie absorb glucose.

But what about in the plant response?

[Reus]

But what about in the plant response?

Plants respond to stimuli through positive or negative tropisms, depending on the growth regulator present.
Relatively work the same method in order to achieve their feedback.

[Reus]

What is specifically meant by saying hormones act by altering the expression of genes?
I know genes comes further on the year, I'd still like to know 

[Frozone]

What is specifically meant by saying hormones act by altering the expression of genes?
I know genes comes further on the year, I'd still like to know 

I'll have a crack here but:
I think this may be talking about the hormone steroid and how they can alter gene expression, I am not too sure.

[vox nihili]

What is specifically meant by saying hormones act by altering the expression of genes?
I know genes comes further on the year, I'd still like to know 

To initiate the transcription of a gene, you need to recruit an enzyme called RNA polymerase. There are a number of different ways this can work, but in general, in eukaryotes RNA pol requires a host of proteins to express genes. These proteins are called transcription factors. What an enzyme may do is alter a transcription factor, allowing it to bind. It may also bind itself at a different site.

[katiesaliba]

Okay, so:
1) does depolarisation and repolarisation occur during the absolute refractory period (cannot receive action potentials) and does hyperpolarisation and afterhyperpolarisation occur during the relative refractory period (raised threshold)?
2) do potassium channels close during afterhyperpolarisation?
3) Do inhibitory postsynpatic potentials reduce the likelihood of an action potential occuring by lowering the threshold? If so, how do they do this?

[Scooby]

Okay, so:
1) does depolarisation and repolarisation occur during the absolute refractory period (cannot receive action potentials) and does hyperpolarisation and afterhyperpolarisation occur during the relative refractory period (raised threshold)?
2) do potassium channels close during afterhyperpolarisation?
3) Do inhibitory postsynpatic potentials reduce the likelihood of an action potential occuring by lowering the threshold? If so, how do they do this?

I hope you're just asking all those questions because you're interested...

[vox nihili]

I hope you're just asking all those questions because you're interested...

Seems to be a lot of schools that are unnecessarily teaching this stuff. One of my students goes to one of the most under-performing schools in the state and he brought back a sheet with this stuff on it, absolutely ridiculous.

[swagsxcboi]

Seems to be a lot of schools that are unnecessarily teaching this stuff. One of my students goes to one of the most under-performing schools in the state and he brought back a sheet with this stuff on it, absolutely ridiculous.

I had questions about action potential on my SACs, actually so pathetic

[soNasty]

where are neurotransmitters produced? Also, when they bond to the post synaptic.. knob? vessel? (i forgot what its called), does it form an ion channel such that it can pass through via (endocytosis? or diffusion?) to the begging of the next neurone? sorry im a bit muddled.