Why is photosynthesis considered a
bridge between the nonliving and living
worlds?

The process of photosynthesis is considered as a bridge between the non living and living world because the substrate which is used in this process is non living and the plants that convert this into useful product is a living thing.

The carbohydrates that is produced by the plants body is used by the plants and animals which is also living thing.

The oxygen which is produced as a by-product is also used by the plant and animals and they are also living components of life.

Hence, it acts as a bridge between the living and non living components of life.