Hurrah, we come to the end of the module! We started the module wondering bananas are curved in shape. Banana fruit grows from the branch downwards.
Initially, the fruit is straight in shape. But, as it grows, it needs light. So, it starts to curve away from the straight line in order to find sunlight away from the tree's shade.
As we discussed in the module, this is phototropism. So, the curved shape of bananas is due to the banana trying to find light away from the shade of its own plant.