Compensation Points of Ivy

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whisper
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Compensation Points of Ivy

Post by whisper » Tue Mar 20, 2007 4:36 pm

I have to write a plan investigating the compensation points of ivy sun and shade leaves using Hydrogen Carbonate Indicator. Does anybody have any idea about the kind of investigation i need to carry out? How it would go etc? Any help would be much appricated. x

ivygirl_5
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Post by ivygirl_5 » Mon Mar 26, 2007 10:47 pm

You know that Compensation Point is the amount of light which is needed to maintain a balance between respiration and photosynthesis.
The rate of respiration is constant (at any given temperature and O2 concentration) for a particular leaf, irrespective of the amount of light.
The rate of photosynthesis increases with increasing light intensity.
There is an amount of light at which photosynthesis is just in balance with respiration.
At this point, the rate at which respiration is producing CO2 is just balanced by the rate at which photosynthesis is using up CO2.
This is the compensation point.

If CO2 is taken away from Hydrogen carbonate indicator (Hci) it becomes purple.
If CO2 is added to Hci it becomes yellow.
If CO2 is neither added nor taken away, Hci remains Rose.

If a different leaves are enclosed with Hci for a length of time at different light intensities, in some tubes the Hci will become yellow, in some it will be purple and in some it will be unchanged.
The leaves in which the Hci is unchanged are at their compensation point.

You can vary the amount of light by placing the leaves at different distances from a lamp, or placing layers of tissue paper between the leaves and the lamp.


Ivy has an enormous amout of variation in the leaves. There are differences between the leaves of ground creeping and aerial shoots, flowering and non-flowering shoots and juvenile and mature shoots. How far differences relate to sun and shade is not clear and it may prove difficult to isolate the variables.

This answer came from the Science and Plants for Schools website.

I hope this helps.

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