Heat energy moves in predictable ways, flowing from warmer objects to cooler ones until both objects are at the same temperature. Electrical circuits provide a means of converting electrical energy into heat, light, sound, chemical or other forms of energy. The sun is a major source of energy for changes on the Earth's surface. The sun's energy arrives as light with a range of wavelengths, consisting mainly of visible light with significant amounts of infrared and ultraviolet radiation. Electricity and magnetism are related forms of energy.
Some organisms reproduce asexually.
Other organisms reproduce sexually. In many species, including humans, females produce eggs and males produce sperm. An egg and sperm unite beginning the development of a new individual. Sexually produced offspring are never identical to either of their parents. Each organism requires a set of instructions for specifying its traits.