Final answer:
The statement that myosins are motor proteins that use ATP hydrolysis energy to move along actin filaments is true. These movements are fundamental to muscle contraction and various cellular processes. Option number b is correct.
Step-by-step explanation:
Myosins are indeed motor proteins that use the energy of ATP hydrolysis to move along actin filaments, making the statement B. True. They are especially plentiful in muscle cells and are critically involved in muscle contraction. The process involves myosin heads binding to actin filaments and then, powered by the hydrolysis of ATP, pulling the actin filaments towards the center of the sarcomere in a movement known as the power stroke. This action shortens the sarcomere, effectively contracting the muscle.
The filamentous structure of actin serves as the track upon which myosin proteins 'walk', and this dynamic interplay between these proteins is essential for various cellular activities including cell division and cellular motility, such as cytoplasmic streaming in plant cells. The ATPase activity of myosin is what converts ATP into ADP and inorganic phosphate, releasing the necessary energy for conformational changes that result in movement.