Final answer:
If there is no barcode on a tube label, important information to include is the name of the substance, any necessary warnings or precautions, and the date of preparation or expiration.
Step-by-step explanation:
If there is no barcode on a tube label, there are still important pieces of information that should be included. First, the name of the substance or material in the tube should be clearly stated. This helps identify what is inside the tube, especially if there are multiple tubes being used. Secondly, it is important to include any necessary warnings or precautions. For example, if the substance is hazardous or requires special handling, this information should be clearly stated on the label. Lastly, the date of preparation or expiration should be included so that users know how fresh or safe the contents are.