As part of a science experiment, Jose did a test for starch on a slice of apple and a slice of potato. The yellow-orange iodine solution stayed the same color when it was put on the apple, but it became black on the potato.

See explanation

Explanation:

Iodine solution is used to test for starch.  A positive test for starch gives a blue-black color.

The fact that the color of the apple remained the same is indicative of the fact that starch was not contained in the apple.

A change in the color of potato indicates the presence of starch in the potato.

The fact that iodine did not react with apple should not be taken to mean that apples contain no starch at all. Starch changes gradually to sugar as fruits ripen. This is why the apple gave a negative test for starch.