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Plant Sciences, Zoology & Evolution / What is the evolutionary advantage of variegated leaves?

« on: 09/11/2011 20:48:57 »

Since apparently the white parts of the variegated leaves don't containt chlorophyll and can't be used for photosynthesis - what is the evolutionary advantage of having variegated leaves.

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Plant Sciences, Zoology & Evolution / How much plant material to provide me with oxygen?

« on: 05/09/2011 19:06:57 »

How much plant material would I need to provide me with sufficient oxygen to breath.  Do all plants produce oxygen at the same rate per kg of material?

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Physics, Astronomy & Cosmology / If light wins the speed race, what comes second?

« on: 21/09/2010 06:48:36 »

Since nothing travels faster than light (or other electromagnetic radiation), what travels second fastest.  Is there some natural upper limit on the speed which can be attained by other things or could anything theoretically reach the speed of light e.g could a single atom ever travel at the speed of light, could sound travel at the speed of light etc?

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Plant Sciences, Zoology & Evolution / How can you tell when a plant has died?

« on: 01/07/2010 21:12:44 »

If you want to tell the point at which an animal has died, you can identify when its heart stopped beating or brain activity ceased.  If you wired up a plant to the necessary equipment could you tell the point at which it died, what would you measure and how would you measure it?

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Physics, Astronomy & Cosmology / What makes a metal a metal?

« on: 08/06/2010 09:47:00 »

I understand that metals have a series of properties - sonorous, conduct heat & electricity etc etc.  But do the properties of the element define it as a metal or is there something about the structure of the element that makes it metal and have these properties.  So if an imaginary new element was found, could you tell just from the structure of the atom whether it was going to be classified as a metal or would you need to look at its properties first.

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Physics, Astronomy & Cosmology / Will sound travel an equal distance?

« on: 16/02/2010 10:37:17 »

If I stood on top of a building, faced forward, and shouted, would the sound travel an equivalent distance  up and down or is there anything which would limit its movement up e.g gravity, air pressure etc.

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Plant Sciences, Zoology & Evolution / How sensitive is a human's taste sense

« on: 04/02/2010 11:14:25 »

I've often heard reference to the fact that human's have a far inferior sense of smell to other mammals, but I'd be interested to know how sensitive our sense of taste is, and how it would be measured.

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Plant Sciences, Zoology & Evolution / What is the world population of mammals?

« on: 22/01/2010 07:15:53 »

Does anyone know how many mammals there are in the world, excluding humans?

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Physics, Astronomy & Cosmology / What makes iron, cobalt and nickel magnetic?

« on: 29/12/2009 19:05:58 »

I believe iron, cobalt and nickel are the only magnetic metals.   Why is this and is a coincidence that they are next to each other on the periodic table?


[MOD EDIT - PLEASE ENSURE THAT YOU PHRASE YOUR THREAD TITLES AS QUESTIONS, IN LINE WITH THE FORUM POLICY. THANKS. CHRIS]

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Chemistry / Why is there so much oxygen in water but so little free in the atmosphere?

« on: 14/07/2009 07:28:43 »

I was listening to a radio programme recently where they mentioned that in the past the earth had very little oxygen in the atmosphere (2% I think was the figure).  This left me wondering how there could be so much oxygen in the water and so little in the atmosphere.

Am I correct in assuming that there is actually a lot of oxygen in the water.  Perhaps the amount of water compared to the amount of atmosphere is small.

Does the hydrogen bond so strongly and easily with oxygen that it can't 'escape'?  But if that were true then why is there any oxygen in the atmosphere.

Can anyone explain

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Physics, Astronomy & Cosmology / How big before an object has a demonstrable gravitational effect?

« on: 26/06/2009 14:12:59 »

How big does something have to be before it would have a noticeable gravitational impact.  It would obviously be something bigger than Everest since people don't seem to feel any sensation of being pulled towards it.

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Physiology & Medicine / Children's Faces

« on: 10/06/2009 11:48:17 »

Watching my children and their friends grow up, it seems to me that their facial feature which changes the most is the nose.   Is this an accurate perception and if so is there any known reason for it?

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Physics, Astronomy & Cosmology / What is the maximum speed of sound?

« on: 06/06/2009 09:47:49 »

Thanks, my question was about what is the maximum speed that sound could travel in any environment.  For example are there any circumstances real or theoretical where sound could travel at the speed of light?

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Physics, Astronomy & Cosmology / What is the maximum speed of sound?

« on: 04/06/2009 12:03:35 »

Is there a theoretical maximum speed of sound?