Kelp is very sensitive to temperature change. Placing the plant near the window and exposing it to direct sunlight will result in continuous warming of the water in which the kelp plant is growing. Research has shown that kelp plant degrades very quickly when temperature increases due to tissue loss.
The energy released is used for assembly of actin filament with myosin head. when myosin is attached to ATP its heads cannot bind to actin and therefore muscle will remain in relaxed form. However during muscle contraction an enzyme referred to as ATPase hydrolyses ATP to ADP and organic phosphate in the process releasing energy. The energy released changes the position of head of myosin which facilatate its binding with actin. Myosin moves towards m-line dragging actin along with it reducing the length of sarcomere leading to muscle contraction.
Light is a form of EM radiation.
EM radiation has no mass (it's just energy packets called photons).
EM radiation can travel through a vacuum. (The speed of light in a vacuum is called c and is around 300,000 m/s).
Hope this helps!