Green plants effectively fix energy from sunlight to make carbohydrates.
This is achieved through the process of photosynthesis, which is basically
a two-stage process. All living organisms, including green plants, also
undergo cellular respiration - the process of making energy available to the
organism by breaking down molecules, such as glucose (a carbohydrate). This
can be done both with or without oxygen. However, the amount of energy made
available is much greater when oxygen is available and can be used. Plants
do this to enable growth, repair and reproduction, as we do.
It is true that, when photosynthesising, green plants release oxygen as a
waste product. At the same time, they are releasing carbon dioxide from
aerobic cellular respiration. It is possible for green plants to use the
carbon dioxide produced in cellular respiration in photosynthesis and to use
the oxygen produced in photosynthesis in cellular repiration. The point at
which the amount produced and used in each of these two processes is the
same is known as the compensation point. Thesefore, you might expect a
plant to produce more oxygen than carbon dioxide during the day (when it is
light) and the reverse when it is dark at night. I don't know the numbers
involved. Hope this helps.
David.
"Matalog" <matalog at ntlworld.com> wrote in message
news:jDFTe.9267$VB1.5210 at newsfe1-gui.ntli.net...
>I understand that when sunlight is around trees and plants will give off
> oxygen and soak up carbon dioxide (photosynthesis) - but at night is it
> true
> that they will give off carbon dioxide? If so, how much of each will be
> released during the night and day.
>> Thanks for any answers.
>> P.S. At night do they take in oxygen?
>>
