Final answer:
A facultative anaerobe is an organism that can grow with or without oxygen. It uses other electron acceptors besides oxygen for growth. Oxygen availability affects the rate of growth, with more growth occurring in the presence of oxygen.
Step-by-step explanation:
A facultative anaerobe is an organism that can grow both with and without oxygen. While it can utilize oxygen for growth, it is also capable of growth in the absence of oxygen. Oxygen availability affects the rate of growth, with more growth occurring in the presence of oxygen. Facultative anaerobes use other electron acceptors besides oxygen, allowing them to carry out fermentation or anaerobic respiration.