Question

$\mathrm{Sort}\mathrm{the}\mathrm{following}\mathrm{steps}\left(\mathrm{from}\mathrm{top}\mathrm{to}\mathrm{bottom}\right)\mathrm{involved}\mathrm{in}\mathrm{the}\mathrm{treatment}\mathrm{of}a\mathrm{leaf}\mathrm{to}\mathrm{test}\mathrm{for}\mathrm{the}\mathrm{presence}\mathrm{of}\mathrm{starch}.$

• A. $\mathrm{Boil}\mathrm{in}\mathrm{spirit}$
• B. $\mathrm{Boil}\mathrm{in}\mathrm{water}$
• C. $\mathrm{Blue}-\mathrm{black}\mathrm{color}$
• D. $\mathrm{Perform}\mathrm{iodine}\mathrm{test}$
• E. $\mathrm{Placed}\mathrm{in}\mathrm{hot}\mathrm{water}$

Answer 1

To test a leaf for starch: Leaf is boiled in hot water for a minute to kill all the cells. Then the leaf is boiled in methylated spirit over a water bath till it becomes pale white to remove chlorophyll. The leaf now becomes hard and brittle. So it is placed in hot water to soften it. The leaf is now spread in a petridish and iodine solution is poured on it. The region of leaf containing starch turns blue black whereas the region without starch will show brown colouration.