The eye bends light through the Cornea; which does the majority of the bending of the light, and the Lens, which fine tunes the light.
The deer showed the greatest change
Almost always it's a case of opposites attract. In general metals give away electrons to the non metals on the right side of the periodic table. The metals have a + charge, the non metals have a - charge. Instant attraction. The attraction is pretty powerful: the ionic bond is among the strongest in chemistry.
Breaking down food molecules gradually and capturing their chemical energy.