Which of the following statements is true about enzyme regulation?

Covalent modifications are a critical mechanism of enzyme regulation that can alter enzyme activity and function. This process involves the addition or removal of chemical groups (such as phosphate groups during phosphorylation) to specific amino acids in the enzyme. These modifications can lead to conformational changes that either activate or inhibit the enzyme's activity.

Covalent modifications allow for precise control over enzyme functions in response to various cellular signals, metabolic needs, or environmental conditions. This form of regulation is essential for maintaining homeostasis and enabling cells to adapt to changes.

In contrast, while temperature can influence enzyme activity through effects on molecular motion and structure, it is not a primary regulatory mechanism like covalent modification. Furthermore, enzymes are not always active at their highest capacity; they can be inactivated or activated based on regulatory mechanisms. Lastly, the statement that enzymes are not regulated at all contradicts the fundamental understanding of enzymology, where regulation is crucial for the proper functioning of metabolic pathways.