Question

A plant was kept in a room for a week. When its leaves were tested with Iodine solution, it did not show the presence of starch. From this experiment we can conclude that ---- is required for photosynthesis.
A) Sunlight
B) Iodine
C) Starch
D) Darkness

Answer 1

Hint:Iodine test is done to find out the presence of carbohydrate. It is performed by using an Iodine solution. The test is known as the Iodine starch test. Starch test is used to check whether photosynthesis has occurred or not.

Complete answer:
Photosynthesis is the process in which plants prepare their food in the form of starch in the presence of sunlight and chlorophyll.
The chlorophyll in the leaves absorb the sunlight and then the photosystems get activated. This leads to production of starch. If the sunlight is absent then the photo system does not get activated so no starch is synthesised.
According to the question, the plant was kept in a room and did not show the presence of starch. It means that photosynthesis has not taken place in the absence of sunlight.
>Iodine- It is the solution used to test the presence of starch. It turns blue-black in the presence of starch.
>Starch- The food prepared by the plant is stored in the form of starch.
>Darkness- Absence of sunlight.

Thus the correct answer is option (A).

Note:Photosynthesis is an important process in the plant. The plants utilize carbon dioxide, water vapour and produce glucose and oxygen and energy as the by product.