Suggest why water was added to cups A and C.

2.1.

The color for buffer X matches the color for pH 4.

2.1.

The color for buffer Y matches the color for pH 8.

• pH of buffer X: 4
• pH of buffer Y: 8

2. (b)

• Cup A: $25 \text{ cm}^3 (\text{fruit}) + 5 \text{ cm}^3 (\text{buffer X}) + 2 \text{ cm}^3 (\text{water}) = 32 \text{ cm}^3$
• Cup B: $25 \text{ cm}^3 (\text{fruit}) + 5 \text{ cm}^3 (\text{buffer X}) + 2 \text{ cm}^3 (\text{enzyme}) = 32 \text{ cm}^3$
• Cup C: $25 \text{ cm}^3 (\text{fruit}) + 5 \text{ cm}^3 (\text{buffer Y}) + 2 \text{ cm}^3 (\text{water}) = 32 \text{ cm}^3$
• Cup D: $25 \text{ cm}^3 (\text{fruit}) + 5 \text{ cm}^3 (\text{buffer Y}) + 2 \text{ cm}^3 (\text{enzyme}) = 32 \text{ cm}^3$

The volume of enzyme and water is the same ($2 \text{ cm}^3$).

This allows for a fair comparison between the experimental setups (B and D with enzyme) and the control setups (A and C without enzyme), as it maintains the same concentration of other components.

• Water was added to cups A and C to keep the total volume of the mixture constant (or to ensure a fair comparison/control).