Question

The diagram below illustrates an experiment to show carbon (IV) oxide is necessary for photosynthesis. The corks have been smeared with Vaseline to prevent entry of gases.

1. Why is it necessary to place the plants in the dark for two days before starting the experiment?
2. What is the role of soda lime?
3. Give the results you would expect if the leaves A and C were subjected to an iodine test after being in bright sunlight for 6 hours.
4. Explain the results given in (C ) above 

Answer 1

1. To remove all starch from the leaves (To destarch the leaves)
2. To absorb carbon (IV) Oxide
3.     
   • A - would be stained brown 
   • C -Would be stained blue – black 
4.   
   • Leaf A was deprived off carbon (IV) Oxide, which prevented photosynthesis from taking place.
   • Leaf C had access to carbon (IV) Oxide; photosynthesis took place