Describe the process of diffusion with reference to the movement of iodine and starch solutions across Visking tubing.

a) Name the physiological process being investigated.

The physiological process being investigated is Diffusion.

b) State the expected colour of the solutions inside and outside the Visking tubing after 30 minutes.

• Inside: The solution inside the Visking tubing will turn blue-black.
• Outside: The solution outside the Visking tubing will remain yellowish-brown (the color of iodine solution), possibly becoming lighter.

c) Explain the observation made in 10(b) above.

Iodine molecules are small enough to pass through the partially permeable Visking tubing by diffusion from a region of higher concentration (outside) to a region of lower concentration (inside). Once inside, the iodine reacts with the starch present in the banana paste, forming a blue-black complex. The concentration of iodine outside decreases as it diffuses inwards, but it will still retain its original yellowish-brown color.