Science locates necessary info about how the universe works. Engineering invents practical devices and systems using the knowledge learned by science. Technology is the collection of <span>products of engineering that can be used to solve problems and perform useful </span><span>tasks.</span>
In order to create a hydroelectric power plant, you need water, hence the prefix hydro-. Most times, people use dams to block the water, which in a way stores it. When you need to produce electricity, you release some of the water which flows through a turbine making it spin, which then activates a generator to produce electricity.
The photoreceptors would be your eyes, chemoreceptors skin, olfactory for nose and mechanoreceptors for obviously tongue hope this helps.