A large asteroid or comet impacted the earth.
The branching point on a cladogram represents a common ancestor. A cladogram is a diagram used in cladistics to show relations among organisms. However it is not an evolutionary tree since it does not show how ancestors are related to descendants, nor does it show how much they have changed.
In photosynthesis o2 is released while in cellular respiration o2 is taken.
Photosynthesis occur in the presence of sunlight while cellular respiration has no boundations
Both require o2.
Both leads to the formation of new substance.