An organism’s ability to maintain its internal rhythm is referred to as its internal clock internal rhythm biological clock biological rhythm

The ability of a certain organism to maintain its internal rhythm is referred as: biological rythm.

Explanation:

The biological rhythm is the ability of a certain organism to manage its processes. It can go from rest to reproduction cycles. It works based on the different systems and substances that the organism has and requires to function. In many cases proteins and energy substances are general. But they can vary depending on the organism, for example, plant cells will require different elements to function than animal cells. Therefore, we can't generalize about certain substances or systems.  

Wikipedia's

Plants and animals use glucose as a soluble, easily distributed form of chemical energy which can be 'burnt' in the cytoplasm and mitochondria to release carbon dioxide, water and energy