Question

A healthy croton plant bearing variegated leaves was kept in a dark cupboard to destarch it after which it was placed in sunlight for a few hours. One of the leaves was then plucked and an outline of the leaf marking the green and the non-green regions was drawn. The leaf was then tested for starch. Using the above information, answer the following questions:

1. State the aim of the above experiment.
2. Name the chemical used for testing the presence of starch.
3. Why is the leaf boiled in water and alcohol before testing for the presence of starch?
4. What change is seen on the leaf after the starch test?
5. Give the chemical equation to represent the process of starch formation in plants.

Answer 1

1. Chlorophyll is necessary for photosynthesis.
2. Iodine solution.
3. the leaf is boiled in water to kill the cells and boiled in alcohol to remove chlorophyll.
4. The green parts of the leaf turned blue-black while non-green parts turned brown.
5. \[\ce{6CO2 + 12H2O->[Light energy][ChlorophyII]C6H12O6 + 6H2O + 6O2 ^}\]