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

Answer 1

Correct answers:
- 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

Why: each of these would cause starch contamination outside the tubing (starch left on the tubing surface, transferred by a shared dropper, or already present in a dirty beaker). Adding glucose to the tubing would not make starch appear in the beaker (glucose can diffuse out, but it is not starch).