AP BIOLOGY

Detailed explanation-1: -Solar energy is created by nuclear fusion that takes place in the sun. Fusion occurs when protons of hydrogen atoms violently collide in the sun’s core and fuse to create a helium atom. This process, known as a PP (proton-proton) chain reaction, emits an enormous amount of energy.

Detailed explanation-2: -Nearly all of the earth’s energy comes from the sun. Some of this radiant energy is reflected by water droplets and dust particles in the atmosphere and bounced back into space or scattered throughout the atmosphere; some is absorbed by clouds or ozone.

Detailed explanation-3: -The amount of energy/matter in the universe is constant and derives from the mysterious big bang. Over time, this becomes more and more spread out and less and less useful, even though the actual amount doesn’t change.

Detailed explanation-4: -The sun is the closest star to Earth. Even at a distance of 150 million kilometers (93 million miles), its gravitational pull holds the planet in orbit. It radiates light and heat, or solar energy, which makes it possible for life to exist on Earth. Plants need sunlight to grow.