Obligate is the opposite of facultative in biology. Treaty is the opposite of facultative in insurance.

Capable of switching to fermentation

Can live with our without oxygen, preferentially use aerobic respiration. -> Can use fermentation as alternative in absence of oxygen

1.Depends upon whether the mutualism is facultative

a. Facultative pollinators - example: honeybees and crop plants (oranges, strawberries, wildflowers)

(1)At no point in this graph do the isoclines cross

(2) This mutualistic interaction is run-away facultative mutualism

ADH is the hormone responsible for facultative water reabsorption.