Question

in an experiment on photosynthesis , a student fixed a strip of black paper on the dorsal surface of a bouganvillea leaf in the morning .in the evening she tested the leaf for starch . the result was a ) the dorsal surface of the leaf was white but the ventral surface turned blue b ) both the surface of the covered portion remained white c ) the entire leaf turned blue black d ) the entire leaf remained white i know that its (c) but why ?

Answer 1

a) The dorsal surface of the leaf was white but the ventral surface turned blue.
Because the ventral surface was exposed to sunlight so photosynthesis took place there whereas the the dorsal surface which was covered with black paper didn't receive the sunlight so photosynthesis didn't take place there. During photosynthesis, Starch is produced and when iodine is made in contact with the part containing starch it turns blue-black while the dorsal part remained white because there was no starch present there.

Answer 2

Answer:

c ) the entire leaf turned blue black

Explanation:

IN A STARCH TEST THE LEAF WILL ALWAYS TURN BLUE-BLACK.

THIS HAPPENS BECAUSE THE TEST IS BLUE SHOWING PHOTOSYNTHETIC PARTS AND BLACK FOR PART COVERED WITH BLACK PAPER.