A2 - New discussion

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Explain how growers apply a knowledge of limiting factors in enhancing temperature, carbon dioxide concentration and light intensity
in commercial glasshouses. You should also be able to evaluate such this using appropriate data. (Discussion should always be researched.)

Posted: 24-11-09 20:58 by Mike McNicholas

McNic you're a keeno!

Right, here goes.

The growers would use artificial lighting - if needed - to raise the light intensity so that it was not a limiting factor. They could also heat the greenhouse, usually by burning gas. This would mean temperature is not a limiting factor. The burning of gas would also raise the level of CO2. However, this will cost money so the growers have to take into consideration how much profit they will make and see if it will cover the cost of the extra lighting and stuff :] Therefore the growers have to chose the optimal combination of light intensity, temperature & CO2 concentration that gives the highest yield and the most profit.

Posted: 24-11-09 21:41 by Lauren Carry

It is years since I have been called a keeno. Well chuffed! However, is it not the case that you, as the winner of round 1 and now as first poster of round 2, are in fact the bigger keeno? Don't get me wrong, I am very pleased to have engendered Keenoism in students. Except Will obviously.

Ethene can also aid ripening of fruit.

Posted: 24-11-09 22:47 by Mike McNicholas

Man, you are too cool for school.

Posted: 25-11-09 09:20 by Lauren Carry

Comercial growers in the UK have a difficult task in comparrison with other countries. What am I talking about? ... Of course you've guessed it, the UK doesn't have ideal growing conditions for any form of plant other than well potatoes or potatoes :)

Ok firstly lets tackle the climate... Plants require an optimum temperature to ensure the quickest rate of photosythesis. The temperature will affect the rate at which the enzyme Rubisco will work within the light-independant reaction (Krebs Cycle). The more effiecently we can make Rubisco catalyse the reaction of the addition of carbon from the carbon dioxide to ribulose bisphosphate the faster growth will be.

As for the idea of carbon dioxide concentration, lets apply a little rule about kinetics. If Carbon dioxide is pumped round the green house at a higher pressure it will increase the random motion and movement of the gas. This will increase the likeihood of a carbon dioxide molecule combinding with ribulose bisphosphate, this in turn again will speed up the rate of photosythesis as it will allow Krebs Cycle to work faster which again will produce faster growth.

The light in the reaction is needed as part of the light dependant reaction the longer there is an avaliability of light the more photolysis of water can be carried out to produce the electrons and protons that are then used up in the light dependant reaction. This too plays an important part of growth of plant. Obviously too the by-product or waste product of this reaction oxygen is quite useful :)

Ooh This is random but I found a different gas that helps with the ripening of fruit which obviously means the quicker a plant can ripen the quicker they can be harvested and another set of crops re-grown. If anyone decided to watch the programme before Waterloo Road on Wednesday night "Jimmy food factory" there was a section on ripening of fruit and he mentioned the gas Ethylene. He conducted an experiment on well bananas and found that they ripened faster when they had been given some of this gas. That was just a random geeky out-burst ... I'm not too sure if that gas works with all crops though.

Posted: 26-11-09 21:03 by Matthew Maguire

Wow Matty. You have just proved that you are infact the bigger keeno.

Posted: 27-11-09 10:32 by Lauren Carry

Yesss! 8) I "Out keenoed" Mcnic 8)

Posted: 27-11-09 12:37 by Matthew Maguire

Not cool Matty. Not cool.

Posted: 27-11-09 19:44 by Lauren Carry

Ethene is the same as ethylene (old name). I am surprised the Chemists didn't spot that.Ethyl group and methyl groups are the terms used in organice chemistry.

Posted: 28-11-09 22:11 by Mike McNicholas

"organic" - never type with a baby as the assistant.

Posted: 28-11-09 22:15 by Mike McNicholas

HAHAHA that well made me chuckle :D organice.

Posted: 29-11-09 17:30 by Lauren Carry

Just so you all know..

Methyl contains 1 carbon and Ethyl... 2 carbons

Ethene - is an alkene so therefore contains a double bond between the 2 carbons and has in total 4 hydrogens

Why you all need to know this i don't know but yeh there you are ;-)

Posted: 29-11-09 19:02 by Banisha Nayyar

Ethene is an example of an unsaturated hydrocarbon and is subject to electrophilic attack by electrophiles. The reaction is due to the electron density within the double bond.Hydrogen bromide, or indeed bromide, are good examples of electrophiles. Bonds are polarised within the molecules depending on the partnered atoms.

Anyway... this is Biology and not organic Chemistry.

Posted: 29-11-09 20:52 by Mike McNicholas

Chemistry geeks...

Posted: 29-11-09 22:01 by Lauren Carry