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?

What does your science teacher say?

Couldn't you find any websites on photosynthesis when you did your Google
search?


"Matalog" wrote in message
...
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?

"Matalog" schreef
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.

***
That is fairly simple. Take the tree or plant when it dies, add all the
material (leaves, fruits, seeds, etc) that it shed over its lifetime, burn
all this and measure the resultant CO2. Divide this by the lifetime of the
tree or plant. This will give the average net take up of CO2. Take it from
there.
PvR

In article ,
Matalog wrote:
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?

They take in oxygen and release CO2 day and night, just as animals do.
However, in adequate light they also photosynthesize, converting CO2
and water to carbohydrates and oxygen. Thus they make their own "food",
carbohydrate, which they burn with oxygen for metabolic energy , just
as animals do.

If they don't get enough light to photosynthesize more than they need to
metabolize, they can't grow and will eventually die. Of course, they use
carbohydrate to build cellulose and other stuff too. But the short answer
is that a growing plant releases more oxygen and absorbs more CO2 than the
reverse.

"Cereus-validus......." wrote in message
...
What does your science teacher say?

I've left school.


Couldn't you find any websites on photosynthesis when you did your Google
search?

Yes, but none mentioned the levels of each that they release during day and
night.


I was looking for a percentage - e.g. at night plants release on average 20%
(carbon dioxide) of the amount of oxygen that they released during the day.





"Matalog" wrote in message
...
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?

wrote in message
...
In article ,
Matalog wrote:
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?

They take in oxygen and release CO2 day and night, just as animals do.
However, in adequate light they also photosynthesize, converting CO2
and water to carbohydrates and oxygen. Thus they make their own "food",
carbohydrate, which they burn with oxygen for metabolic energy , just
as animals do.

If they don't get enough light to photosynthesize more than they need to
metabolize, they can't grow and will eventually die. Of course, they use
carbohydrate to build cellulose and other stuff too. But the short answer
is that a growing plant releases more oxygen and absorbs more CO2 than the
reverse.

Any average percentages of each?

I was looking for a percentage - e.g. at night plants release on average 20%
(carbon dioxide) of the amount of oxygen that they released during the day.

That is going to depend on the species, the growing conditions (light,
moisture, temperature, etc.) Many factors affect metabolism, and I'm not
sure there's a constant percentage.

M. Reed

I was looking for a percentage - e.g. at night plants release on average
20% (carbon dioxide) of the amount of oxygen that they released during the
day.

"monique" schreef
That is going to depend on the species, the growing conditions (light,
moisture, temperature, etc.) Many factors affect metabolism, and I'm not
sure there's a constant percentage.

M. Reed

***
Not to mention differences in day length!
PvR

It's difficult to generalize about plant CO2 uptake because it ranges
widely over time and for different crops and biomes. Plant productivity
is often expressed as grams of dry matter produced per square meter of
ground area per day or kilograms/square meter/year. One of the highest
short term figures I've seen is 50 g/square meter/day for a corn crop
during grain filling. Search google.com for net primary productivity
(NPP) to find more data.

Here's a neat, color global map showing how NPP changes over two years:

http://earthobservatory.nasa.g ov/Newsroom/NPP/npp.html

Salisbury and Ross's 1985 Plant Physiology text had Table 11-1 with NPP
data for natural ecosystems and cultivated areas. Their annual average
for tropical rain forest ranged from 2.7 to 9.6 g/square meter/day and
0.27 to 9.6 g/square meter/day for cultivated land.

If you want an idea of the percentage of the carbon fixed during the
day that is respired at night, search for the term maintenance
respiration.

The following webpage gives a generalization that plant respiration
consumes "25% of gross photosynthesis plus 1.5% of existing plant dry
weight per day."

http://www.life.uiuc.edu/plantbio/wimovac/respirat.htm


David R. Hershey