Question

What is the default state of inducible systems, and when do they become active?

Options

• ON by default; they remain ON irrespective of substrate availability

• ON by default; they are switched OFF when the end product is in excess

• OFF by default; they remain OFF until the end product accumulates

• OFF by default; they become ON when a substrate is present

Answer 1

Inducible systems are usually OFF by default and become ON when a substrate is present. This is the opposite of repressible systems, which are ON by default and switch OFF when the end product is in excess.