[URGENT HELP NEEDED] PHOTOSYNTHESIS PRAC SAC

[tzacchary]

So my SAC is tomorrow and I have questions I need to do, and I'm stuck.
I'm doing the one with leaf disks in water and bicarbonate and then bicarbonate x4 but wrapped in different coloured cellophane. (hopefully some of you are doing a similar prac to me and understand what i'm talking about)

What is the control in this experiment?
Why do the leaf disks sink when a vacuum in the syringe is created? (I think it's got something to do with air bubbles or the O2 going out of the cell?)

Thank you so much!

[auds]

The bicarbonate solution without any cellophane acts as a control for the bicarbonate solution with cellophane wrapped around it. The clear cellophane acts as a control for the coloured cellophane.

Because the gases trapped in the spongy mesophyll layers of the leaf are forced out, the leaf discs are not buoyant, therefore sinking.

Hope that helped !

[tzacchary]

The bicarbonate solution without any cellophane acts as a control for the bicarbonate solution with cellophane wrapped around it. The clear cellophane acts as a control for the coloured cellophane

Because the gases trapped in the spongy mesophyll layers of the leaf are forced out, the leaf discs are not buoyant, therefore sinking

Hope that helped !

Thank you so much!