Final answer:
A mutation in Mot A/B, part of the bacterial flagellar motor, is likely to lead to decreased motility by disrupting the conversion of ion motive force into mechanical rotation of the flagella, essential for bacterial movement and chemotaxis.
Step-by-step explanation:
If you have a mutation in Mot A/B, which is part of the bacterial flagellar motor, the most likely consequence would be b) Decreased motility. Mot proteins are integral membrane proteins that form part of the proton channel and are crucial for the function of the flagellar motor. The Mot A/B complex interacts with the flagellar rotor and is essential for the conversion of ion motive force into mechanical rotation. A mutation could disrupt this interaction or function, reducing the efficiency of flagellar rotation and thus leading to decreased motility. This is critical for bacterial chemotaxis, where bacteria respond to chemical gradients by altering flagellar rotation, extending runs and reducing tumbles to move towards an attractant. A mutation that impairs Mot A/B function can compromise these movements.