VCE Biology Question Thread

[RazzMeTazz]

What is the role of NADPH in the Calvin cycle?

Some websites say it is to reduce the 3 phosphoglycerate molecules to produce G3P
but my textbook says it is add hydrogen ions to the 3 phosphoglycerate molecules to produce G3P

Which one is correct?

o.O

[RazzMeTazz]

Generally enzymes aren't listed as 'inputs' in a reaction, if that's what you're asking; the reaction is carried out in the presence of the enzyme, rather than it being a reagent.

  yeah that's what I was wondering. Thankyou!! 

[Scooby]

What is the role of NADPH in the Calvin cycle?

Some websites say it is to reduce the 3 phosphoglycerate molecules to produce G3P
but my textbook says it is add hydrogen ions to the 3 phosphoglycerate molecules to produce G3P

Which one is correct?

o.O

Both of them

[RazzMeTazz]

Both of them

Oh thanks!
So in the Calvin cycle after the NADPH molecules have completed their roles, they would just be NADP+ again?

[lzxnl]

What is the role of NADPH in the Calvin cycle?

Some websites say it is to reduce the 3 phosphoglycerate molecules to produce G3P
but my textbook says it is add hydrogen ions to the 3 phosphoglycerate molecules to produce G3P

Which one is correct?

o.O

To clarify, what happens is the glycerate molecules are "reduced" by replacing the OH group/O- (depending on pH) with a H atom
Yes, H+ ions do end up reacting, but they must also get electrons so that when you add the H+ to the molecule the molecule remains neutral

Oh thanks!
So in the Calvin cycle after the NADPH molecules have completed their roles, they would just be NADP+ again?

Yep.

[Yacoubb]

What is the role of NADPH in the Calvin cycle?

Some websites say it is to reduce the 3 phosphoglycerate molecules to produce G3P
but my textbook says it is add hydrogen ions to the 3 phosphoglycerate molecules to produce G3P

Which one is correct?

o.O

If you were asked for the role of NADPH, you'd need to say that it provides H+ ions that react with carbon dioxide to form glucose.

[vox nihili]

What is the role of NADPH in the Calvin cycle?

Some websites say it is to reduce the 3 phosphoglycerate molecules to produce G3P
but my textbook says it is add hydrogen ions to the 3 phosphoglycerate molecules to produce G3P

Which one is correct?

o.O

There have been some confusing answers to this, because there are a number of things that happen. TO add my clarification (and opinion) to the mix, all you need to know for a VCE level is that the NADPH is an electron carrier. Its role in the Calvin Benson cycle is really restorative and is something that I wouldn't imagine would be asked on a VCE level exam.

[Jason12]

why do plants breakdown starch into simple sugars as part of the fruit ripening process?

oxygen is consumed by plants regardless of whether fruit is ripening? Why? - is this due to cellular respiration?

[katiesaliba]

In the Krebs cycle, does coenzyme A from acetyl coA act as a cofactor for citrate synthase?

[vox nihili]

In the Krebs cycle, does coenzyme A from acetyl coA act as a cofactor for citrate synthase?

No, it is a reactant. Oxaloacetate and acetly coA combine to make citrate.

[DJA]

Could someone explain the complete process of how a lipophilic hormone (steroid) enters a cell and thus signals the cell to carry out a response?

Conversely could someone also explain in contrast how a Hyrdophillic hormone (amino acid/peptide) accomplishes the same thing?

Much appreciated.

[vox nihili]

Could someone explain the complete process of how a lipophilic hormone (steroid) enters a cell and thus signals the cell to carry out a response?

Conversely could someone also explain in contrast how a Hyrdophillic hormone (amino acid/peptide) accomplishes the same thing?

Much appreciated.

You don't really need to know these things exactly, but the basic mechanisms.

Lipophillic

Makes its way through the membrane and into the cell where it associates with a chaperone. This chaperone brings it into the nucleus, where it acts in a biochemical pathway that up regulates or down regulates transcription. In general, lipophillic hormones act as transcription factors.

Hydrophillic

Binds to a receptor on the membrane. These can be a number of different types.
If the receptor is attached to a protein channel, this can cause an influx or outflux of ions. Neurotransmitters are an example of this.
The receptor can also be a G-protein, which undergoes a conformational change and interacts with a secondary messenger that amplifies the signal in the cell. Essentially, that one binding causes the transmembrane protein to stimulate heaps of proteins in the cell so the biochemical effect of the signalling is amplified. That's the signal cascade.




Those are fairly basic concepts, but that should be well more than enough.

[howlingwisdom]

Does the smooth endoplasmic reticulum synthesise lipid based hormones?

[nhmn0301]

Does the smooth endoplasmic reticulum synthesise lipid based hormones?

Yes. And Rough endoplasmic reticulum synthesis protein based hormones.

[jessica666]

in nerve impulses do the sodium and potassium ions move by facilitated diffusion or active transport? or both?