IB Biology SL D3.2.2 Genetic Crosses in Flowering Plants Topic Practice

L. purpureus can have purple or white flowers. Two pure-breeding varieties were crossed: HA 4 with white flowers and GL 424 with purple flowers. All of the $F_{1}$ plants had purple flowers. The $F_{1}$ plants were self-pollinated to produce an $F_{2}$ generation. There were 97 plants with purple flowers and 38 plants with white flowers in the $F_{2}$ generation.

Using a Punnett grid, explain the results of this cross.

Suggest a reason for the $F_{2}$ generation not corresponding exactly to the expected ratio of purple-flowered and white-flowered plants.