What do you suppose the author meant by a “threshold of irreversibility”?

What the author means that even if the process of the ecosystem is irreversible, it is still possible for it to change through the course but still following the cycle in its process. Although, there are still boundaries in how it will cover the system.

Explanation:

What the author means that even if the process of the ecosystem is irreversible, it is still possible for it to change through the course but still following the cycle in its process. Although, there are still boundaries in how it will cover the system.        

hope this helps! :)        

photosynthesis makes the glucose that is used in cellular respiration to make atp. the glucose is then turned back into carbon dioxide, which is used in photosynthesis. while water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.

because photosynthesis could not occur (apex)