Final answer:
Barley grains are seeds that, when soaked in water, begin the germination process. Water triggers the activation of enzymes within the seed, which use stored food to fuel the growth of a new plant.
Step-by-step explanation:
Barley grains are actually seeds, so soaking them in water triggers their germination process. When barley seeds are soaked, the water absorption signals the seed that it is time to start growing. The process of germination begins with the seed imbibing water, which leads to the activation of enzymes.
These enzymes break down the stored food reserves within the seed, providing energy for the growth of the embryonic plant inside. Eventually, the seed will sprout, leading to the growth of a new barley plant.