Final answer:
The statement provided is false as enzyme-substrate binding is not always rigid. The lock-and-key model and the induced fit model illustrate enzyme specificity; however, the induced fit model shows that enzymes can adjust their shape for the substrate.
Step-by-step explanation:
The statement "The substrate will only bind to the enzyme when their shapes fit together rigidly" is not entirely accurate and the correct answer would be B) False. Enzymes and substrates are indeed specific in their binding, but the binding is not always rigid. Two models describe the interaction between enzymes and substrates: the lock-and-key model and the induced fit model.
In the lock-and-key model, it is believed that the enzyme's active site and the substrate have complementary shapes that fit together without the need for alteration. However, the induced fit model indicates that the enzyme's active site can undergo a conformational change to accommodate the substrate, suggesting flexibility. Thus, enzymes can bind substrates with similar but not identical shapes due to this adaptability.
It's important to understand that both models highlight the enzyme's specificity to its substrate, but it can adapt its shape for optimal binding and catalytic efficiency according to the induced fit model. The idea of the enzyme being completely rigid as implied by the question would be a misunderstanding of the dynamic nature of enzyme-substrate interactions.