Fruits in the diet can be a source of vitamins, such as vitamin C and vitamin A, which are important in maintaining good health. Vitamin A is a group of molecules that includes retinol and retinal. Vitamin C is an organic acid known as ascorbic acid. Ripening occurs in fruit when molecular changes cause an increase in sugar content, colour changes and softening of the fruit, over time. Ascorbic acid is found in plant cells. The fruits of many plants have high concentrations of ascorbic acid. A student planned to investigate how ascorbic acid concentration changes with ripeness in the fruit of the apple tree, Malus domestica. The fruit of M. domestica (apples) are shown in [Figure 1.1].