Why did very little if any starch digestion occur in test tube 6a?

In test tube 6a, very little if any starch digestion likely occurred due to the absence of amylase, the enzyme responsible for breaking down starch into simpler sugars. Additionally, if the pH or temperature conditions were not optimal for enzyme activity, this could further inhibit starch digestion. Without these necessary conditions or enzymes, the starch would remain largely intact.