Given below is a sketch of a leaf partially covered with black paper and which is to be used in the experiment to show that light is compulsory for the process of photosynthesis:
![](https://search-static.byjusweb.com/question-images/img/study_content/content_ck_images/images/Pg20263_14.png)
(a) At the end of the experiment, which of the leaf part/leaf parts labelled I, II and III will become blue-black when dipped in iodine solution?
(b) Which substance will be missing in the leaf part/leaf parts which will not become blue-black when dipped in iodine solution?