How many pair/s of contrasting characters in the pod of pea were...

Mendel selected 7 pairs of contrasting characters in pea plants for his experiments.

Out of these, two pairs of contrasting characters were related to the pod of the pea plant:
1. Pod shape: Inflated (dominant) and Constricted (recessive)
2. Pod colour: Green (dominant) and Yellow (recessive)

Therefore, there are 2 pairs of contrasting characters in the pod of pea.

Answer: $2$