AP BIOLOGY

Detailed explanation-1: -3.1 The Sun is the major source of energy for organisms and the ecosystems of which they are a part. Producers such as plants, algae, and cyanobacteria use the energy from sunlight to make organic matter from carbon dioxide and water. This establishes the beginning of energy flow through almost all food webs.

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 flow of energy through living things begins with photosynthesis, which creates glucose. In a process called cellular respiration, organisms’ cells break down glucose and make the ATP they need.

Detailed explanation-4: -It radiates light and heat, or solar energy, which makes it possible for life to exist on Earth. Plants need sunlight to grow. Animals, including humans, need plants for food and the oxygen they produce. Without heat from the sun, Earth would freeze.