Fig. 1.1 A shows the root vegetable beetroot, Beta vulgaris. Fig. 1.1 B shows a single cell from the beetroot tissue. The vacuole contains the red pigment, betalain. The pigment molecules are too large to diffuse out of the vacuole. [Figure 1.1] When pieces of beetroot are soaked in a solution of calcium hypochlorite, Ca(CIO)2, the beetroot tissue changes from red to white. This is caused by the calcium hypochlorite diffusing into the beetroot cell vacuoles and decolourising the betalain pigment. Fig. 1.2 shows a cube of beetroot before soaking in the solution of calcium hypochlorite and the halved cube of beetroot after soaking in the solution of calcium hypochlorite. [Figure 1.2] In a class experiment: • Cubes of beetroot of different dimensions were placed in a beaker containing a 10% solution of calcium hypochlorite. • The cubes were left for 30 minutes. • The cubes were then cut in half, and the width of the tissue remaining red (the red zone) was measured. A group of students investigated the effect of changing the surface area:volume ratio on the diffusion of calcium hypochlorite into beetroot cubes. The students used cubes of different sizes and measured the width of the red zone after soaking the beetroot in calcium hypochlorite. The students suggested the hypothesis: The width of red tissue remaining in the beetroot after soaking in calcium hypochlorite is inversely proportional to the surface area:volume ratio of the beetroot cubes.