=IF(ISBLANK(RC[-1]),"", IF(OR( ISNUMBER(SEARCH("apple",RC[-1],1)), ISNUMBER(SEARCH("banana",RC[-1],1)), ISNUMBER(SEARCH("carrot",RC[-1],1)), ISNUMBER(SEARCH("donut",RC[-1],1)) ), "Yes","No"))
Two comments regarding the previous formula I provided: if the cell to the left is completely blank, then the result cell is also blank. If you don't like that (and ONLY want yes/no, just remove the 1st part of the formula that checks for ISBLANK.
#1. I did notice that most of the previous formulas preferred to check for ISERROR, but this is not the best solution, especially in a case asuch as this since ISERROR finds the case where it fails, whereas ISNUMBER finds the case where is succeeds, which is usually the case we're often looking for.
#2. I used the preferred cell reference of RC vs. A1 format. Using A1 format means you can never Copy/Paste the formula into the formula bar of another cell, but instead you are forced to drag down/over to copy it and have the relative cell references fixed by Excel. (Why they switched from RC format to A1, I could never fathom. It's so much harder to use and to read IMHO.) If you want the formula in A1 format, merely change the RC[-1] references (which references the cell to the left regardless of it's location in the sheet) to the cell reference to the desired location.
For those who want to switch to RC format (or at least see what RC format is), check / change your preferences to R1C1 (I believe the General tab).