What if photosynthesis does not occur in plants?

Photosynthesis:

Green plants, often known as autotrophs, produce or rather synthesize the food they require through photosynthesis.

Importance of photosynthesis:

1. It is the primary source of all food on earth.
2. It is also responsible for releasing oxygen into the atmosphere by green plants.

If photosynthesis did not exist:

1. Plants and animals would most likely perish.
2. Photosynthesis emits considerable oxygen into the air; the atmosphere contains very little oxygen.