Edexcel 6BIO5 ~ 20h June 2014 ~ A2 Biology

Original post by Bioman95

Well i am confused as to what happens to the hydrogen and nads in glycolysis/aerobic/anaerobic respiration. Please help lol im so lost

In my revision guide it says that the NAD produced in aerobic respiration (it is oxidised from reduced NAD in the electron transport chain) is used in glycolysis.
In anaerobic respiration, the NAD formed when pryuvate is reduced to lactate, is also used in glycolysis.
The hydrogens in the Krebs cycle are used in the electron transport chain to synthesise ATP in oxidative phosphorylation.

Hope I helped!

Reply 707

I'm slightly confused. MDMA and SSRIs both block the reuptake of serotonin yet MDMA can cause depression while SSRIs are used to treat depression. Can someone please explain this to me?

Reply 708

Bioman95

Original post by haniie219

I'm slightly confused. MDMA and SSRIs both block the reuptake of serotonin yet MDMA can cause depression while SSRIs are used to treat depression. Can someone please explain this to me?

Thanks for the help and both ssris and mdma work in the same way, they stimilate the neurones producing seratonin and also block the reuptake of it, there is a high concentration of it in the clefts. When they wear off they cause depression as the neurones have used up a lot of the bodoes seratonin levels. The difference with mdma and ssris are that mdma has a more intense effect and more intense after effect. U would be depressed for s while if you came off ur prozac till your body regenerates seratonin. Hope i helped.

Reply 709

Can someone explain the whole plant photoreceptors and day length stuff? It's all so confusing! Thanks :smile:

Reply 710

Original post by Bioman95

Thanks for the help and both ssris and mdma work in the same way, they stimilate the neurones producing seratonin and also block the reuptake of it, there is a high concentration of it in the clefts. When they wear off they cause depression as the neurones have used up a lot of the bodoes seratonin levels. The difference with mdma and ssris are that mdma has a more intense effect and more intense after effect. U would be depressed for s while if you came off ur prozac till your body regenerates seratonin. Hope i helped.

That makes sense! Thank you :smile:

Reply 711

Original post by Rz_22

Can someone explain the whole plant photoreceptors and day length stuff? It's all so confusing! Thanks :smile:

In terms of tropism?

Reply 712

Original post by haniie219

In terms of tropism?

Yes! And how Pfr and Pr work :smile:

Reply 713

student55

does anyone know what the marker gene is used for in genetic modification?
and do we need to know about creating phosphate?
thank you!

(edited 9 years ago)

Reply 714

gemma-t96

1

Does anyone have any possible exam questions for the synoptic article? Or anything that could possibly come up on Friday to do with the article? :smile:

Reply 715

Original post by Rz_22

Yes! And how Pfr and Pr work :smile:

A tropism is a plant's response to an environmental stimuli e.g. Light, hence phototropism.

Shoots have a positive phototropism, they grow towards the light and roots have a negative phototropism, they grow away from the light.

The growth factor in plants is auxin (e.g.IAA). In shoots, auxin stimulates growth and in roots, auxin prevents growth.

When light shines in one direction, it is on the dark side (star wars) of the plant so, the shoot grows towards the light by elongation.

IAA travels short distances by diffusion and active transport and long distances in phloem.

I'm not sure what Pr and Pfr are? Sorry :/ but I hope I helped!

Reply 716

Original post by student55

does anyone know what the marker gene is used for in genetic modification?
and do we need to know about creating phosphate?
thank you!

The marker can be antibiotic resistance.

Reply 717

Original post by haniie219

A tropism is a plant's response to an environmental stimuli e.g. Light, hence phototropism.

Shoots have a positive phototropism, they grow towards the light and roots have a negative phototropism, they grow away from the light.

The growth factor in plants is auxin (e.g.IAA). In shoots, auxin stimulates growth and in roots, auxin prevents growth.

When light shines in one direction, it is on the dark side (star wars) of the plant so, the shoot grows towards the light by elongation.

IAA travels short distances by diffusion and active transport and long distances in phloem.

I'm not sure what Pr and Pfr are? Sorry :/ but I hope I helped!

Thank you so so much! :smile:

Pr and Pfr are the photoreceptors in the plant that detect light.
Pr absorbs red light and Pfr absorbs far red light
When one form of the pigment absorbs light, it is concerted reversibly to the other form.
These phytochromes enable the plant to respond to changes in day length.

I don't get how this links in with the tropism stuff or are supposed to revise them as two different things?

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Reply 718

corrgeorgia

Hi has anyone learnt about anabolic steroids and erythropoietin and their benefits and limitations? :s-smilie:

seen it on someone's revisions notes but it's not on the specification? Would be a great help! :smile:

Reply 719

Original post by corrgeorgia

Hi has anyone learnt about anabolic steroids and erythropoietin and their benefits and limitations? :s-smilie:

seen it on someone's revisions notes but it's not on the specification? Would be a great help! :smile:

It is on the specification 'explain how genes can be switched on and off by DNA transcription factors including hormones'

Do you want me to explain each of them? :smile: