Final answer:
In the absence of oxygen in the root zone, respiration in plants stops, and they switch to anaerobic metabolism and enter a dormant state until sunlight returns.
Step-by-step explanation:
In the absence of oxygen in the root zone, respiration in plants stops. The plant switches to anaerobic metabolism and goes into a dormant state until sunlight returns. Without oxygen, the plant cannot carry out aerobic respiration which is necessary for producing energy through the breakdown of glucose. Instead, it relies on anaerobic respiration or fermentation for energy production.
Learn more about Plant Respiration