Final answer:
Enzymes at the branch points of metabolic pathways are regulated by feedback inhibition, where the end product of the pathway acts as an allosteric inhibitor to control the pathway's activity.
Step-by-step explanation:
The activities of enzymes at the branch points of metabolic pathways are often regulated by a process called feedback inhibition. Feedback inhibition is where the end product of the pathway inhibits an upstream step, serving as an allosteric inhibitor to one or more of the enzymes involved, usually the first committed enzyme of the pathway.
This type of regulation enables the cell to efficiently balance the production and utilization of metabolic products, preventing overproduction and resource waste. Enzymes can be regulated by various means, including cellular conditions like temperature and pH, their location within a cell, and the presence of activators or inhibitors which can act competitively or allosterically.