I believe the answer is 20 feet. According to McBurney and Collings, the average threshold of human hearing is the tick of a watch from 20 feet in very quiet condition.
The human hearing range is a description of the pitches and loudness levels a person can hear before feeling discomfort. There is a variety of sounds in our environment, ranging from faint sounds like birdsong and rustling leaves to louder sounds like music, yelling, and industrial noise.
The mass of a tree is primarily carbon. The carbon comes from carbon dioxide used during photosynthesis. During photosynthesis, plants convert the sun's energy into chemical energy which is captured within the bonds of carbon molecules built from atmospheric carbon dioxide and water.
Mosts animal cell does not have nucles
300 joules of energy. 10% is lost as you go up the pyramid
