Iron is considered an essential element for many bacteria. Based on the animation, how would lack of iron affect energy production of a bacterium?

Leads to low energy yields.

Explanation:

Heme is important to the function of hemoproteins which are involved in the generation of energy, detoxification of the host immune effectors among other processes.

The heme is an iron containing co-factor therefore lack of iron would mean there will be no heme, and thus lower amounts of functioning hemoproteins. Low amount of functioning hemaproteins means there will be lower energy yields.