Question

starch molecules are too large to pass through the tubing into the beaker. which errors could have caused starch to appear in the beaker despite this fact? check all possible errors.
not washing the outside of the tubing after filling it with starch
reusing droppers for different solutions
adding glucose to the solution in the dialysis tubing
using a beaker that had not been cleaned thoroughly

Explanation:

• Not washing the outside of the tubing after filling it with starch: If the outside of the tubing has starch on it (from when it was filled), and it is placed into the beaker, this starch can contaminate the beaker solution, making it seem like starch passed through the tubing.
• Reusing droppers for different solutions: If a dropper was used to handle starch solution and then reused (without proper cleaning) to handle a solution in the beaker (e.g., to take a sample for testing), it can introduce starch into the beaker solution.
• Using a beaker that had not been cleaned thoroughly: If the beaker had residual starch from a previous experiment (because it was not cleaned well), this pre - existing starch can be present in the beaker solution, giving a false positive for starch in the beaker.

Adding glucose to the solution in the dialysis tubing is not relevant to the presence of starch in the beaker. Glucose and starch are different substances, and adding glucose does not cause starch to appear in the beaker.

Answer:

not washing the outside of the tubing after filling it with starch, reusing droppers for different solutions, using a beaker that had not been cleaned thoroughly.