Question

8 question pzzzzz....




Is mass of co2....

Answer 1

in simultaneous measurements of CO2 uptake

and O2 evolution in a sunflower leaf, O2 evolution changed by

7% more than CO2 uptake when light intensity was varied.

Since the O2/CO2 exchange ratio is 1, small differences are

important. Thus, these gas exchange measurements need

precise calibration. In this work, we describe a new

calibration procedure for such simultaneous measurements,

based on the changes of O2 concentration caused by the

addition of pure CO2 or O2 into a flow of dry air (20.95% O2)

through one and the same capillary. The relative decrease in

O2 concentration during the addition of CO2 and the relative

increase in O2 concentration during the addition of O2

allowed us to calibrate the CO2 and O2 scales of the

measurement system with an error (relative standard

deviation, RSD) of 51%. Measurements on a sunflower leaf

resulted in an O2/CO2 ratio between 1.0 and 1.03

under different CO2 concentrations and light intensities,

in the presence of an ambient O2 concentration of

20–50 mmol mol-

1

. This shows that the percentage use of

reductive power from photochemistry in synthesis of inorganic

or organic matter other than CO2 assimilation in the C3 cycle

is very low in mature leaves and, correspondingly,

the reduction of alternative acceptors is a weak source of

coupled ATP synthesis.

Keywords: Alternative electron transport — Carbon dioxide

— Oxygen — Photosynthesis.