Search found 11 matches

by ADAS137
Sun Jan 15, 2012 9:42 am
Forum: Botany Discussion
Topic: Problem understanding result of lighting regime-phytochrome
Replies: 13
Views: 11139

Sort of get it now- the key was that the flash of 'light' which interrupts the nights, is RED light not DAYLIGHT- therefore the conversion into Pfr is very rapid.In contrast accumulation of Pfr in daylight is much slower as there is far red light too which makes the net accumulation smaller. I now a...
by ADAS137
Sun Jan 01, 2012 10:26 pm
Forum: Human Biology
Topic: Confusion: Rod cells,rhodopsin bleaching
Replies: 0
Views: 2076

Confusion: Rod cells,rhodopsin bleaching

I'm confused as to why,when exposed to bright light, rod cells cease to function. I understand that exposure to bright light bleaches all of the rhodopsin, but...so what? Why doesn't the bleached product (opsonin/retinal) simply get re-synthesised back into rhodopsin as it does in dim light, and the...
by ADAS137
Sat Dec 31, 2011 4:16 pm
Forum: Human Biology
Topic: Impulse propagation/local circuits and repolarisation
Replies: 1
Views: 2221

Impulse propagation/local circuits and repolarisation

I'm a little confused about repolarisation and its link with local circuits. As far as i'm aware, repolarisation is due to K+ channels opening, thus outflow causes a fall back to membrane potential. Local circuits are caused because, the influx of sodium ions is attracted to the surrounding negative...
by ADAS137
Thu Dec 15, 2011 4:32 pm
Forum: Botany Discussion
Topic: Problem understanding result of lighting regime-phytochrome
Replies: 13
Views: 11139

I just don't understand regime 3- why doesn't the daylight period following the darkness cause a huge boost in P730 levels, which tell the plant that it shouldn't grow?

My problem is I don't know how fast the accumulation of P730 in daylight is, compared to the accumulation of P600 during night time.
by ADAS137
Thu Dec 15, 2011 4:26 pm
Forum: Botany Discussion
Topic: Problem understanding result of lighting regime-phytochrome
Replies: 13
Views: 11139

Would I be correct in saying that the level of P730 tells the plant 'it's time to grow because we are in a long night, or short night'? So since during night, P730 converts to P660, this low level of P730 makes the plant 'think' that a short day is in place-therefore it's time to grow. And a cheeky ...
by ADAS137
Thu Dec 15, 2011 2:49 pm
Forum: Botany Discussion
Topic: Problem understanding result of lighting regime-phytochrome
Replies: 13
Views: 11139

How much faster is the conversion of Pr--->Pfr during the day, than the conversion of Pfr---->Pr during the night?

Could you please explain regime 3 and regime 4, step by step in terms of phytochrome and hence flowering?!
by ADAS137
Thu Dec 15, 2011 2:42 pm
Forum: Botany Discussion
Topic: Problem understanding result of lighting regime-phytochrome
Replies: 13
Views: 11139

Re:

JackBean wrote:but the length of light is not that important, what matters is length of dark ;)

I don't get why people keep saying that!
by ADAS137
Thu Dec 15, 2011 2:08 pm
Forum: Botany Discussion
Topic: Problem understanding result of lighting regime-phytochrome
Replies: 13
Views: 11139

Basically, i've been taught that ANY period of daylight almost totally converts al p660 into p730. Hence why the flash of light in regime 4 leads to no flowering.

So, if a few minutes of light leads to total conversion, then why doesn't several hours have the same effect?
by ADAS137
Thu Dec 15, 2011 1:52 pm
Forum: Botany Discussion
Topic: Problem understanding result of lighting regime-phytochrome
Replies: 13
Views: 11139

Re:

I'm sorry, but I do not understand your confusion. The regime 3 has full long night, while regime 4 has flash of light inside the night, thus the plant doesn't flower. m I am confused as in regime 3, the long night is followed by a period of daylight. I thought during daylight, P730 accumulates,whi...
by ADAS137
Wed Dec 14, 2011 10:25 pm
Forum: Botany Discussion
Topic: Problem understanding result of lighting regime-phytochrome
Replies: 13
Views: 11139

Re: Problem understanding result of lighting regime-phytochrome

Sorry the link didn't work , here is a picture:http://clip2net.com/s/1oXHb
by ADAS137
Wed Dec 14, 2011 10:23 pm
Forum: Botany Discussion
Topic: Problem understanding result of lighting regime-phytochrome
Replies: 13
Views: 11139

Problem understanding result of lighting regime-phytochrome

I am really confused with a past paper question, on the website m , may/june 2011, A21 (physiology and ecosystems( , question 5. What I don't understand is how lighting regime 3 (given that it is a short day plant) leads to flowering? I thought that even just a flash of daylight leads to the (pretty...