Final answer:
The pair of necks of myosin II consist of two globular subunits that are part of the myosin head. They are responsible for binding to actin during muscle contraction.
Step-by-step explanation:
The pair of necks of myosin II, a motor protein involved in muscle contraction, consists of two light chains. These light chains are part of the myosin molecule and are associated with the globular heads of myosin.
Each myosin II molecule has two heavy chains that form a long fibrous tail and two smaller, flexible light chains that constitute the neck region. The neck region is crucial for the function of myosin II, as it allows the globular heads to pivot and interact with actin filaments during the sliding filament mechanism of muscle contraction.
The interaction between myosin and actin, powered by ATP hydrolysis, is a fundamental process in muscle contraction and various cellular movements.