Q.) Which of the following statements
shows the correct results of Iodine Test
performed on the leaf from plant X and Y
respectively?
(a) Blue – black colour would be obtained on the leaf of plant X and no change in colour on leaf of plant Y.
(b) Blue – black colour would be obtained on the leaf of plant Y and no change in colour on leaf of plant X.
(c) Red colour would be obtained on the leaf of plant X and brown colour on the leaf of plant Y.
(d) Red colour would be obtained on the leaf of plant Y and brown colour on the leaf of plant X.
Ans. (b) Blue – black colour would be obtained on the leaf of plant Y and no change in colour on leaf of plant X.
Explanation: Plant X will not be able to perform photosynthesis as there is no carbon dioxide present in the jar. Hence it will not show positive starch test with iodine. Plant Y will perform photosynthesis as all raw materials are present in the jar. Hence it will show positive starch test with iodine, that is, the leaf would turn blue black when drops of iodine are put on the leaf due to presence of starch in the leaf.
