What is an ecosystem that normally functions without human tending?

What is the difference between the conducting zone and the respiratory zone of the respiratory system? the conducting zone is a series of cavities and tubes that move air to the respiratory zone where gases exchange with the bloodstream. the conducting zone exchanges gases between the lungs and the alveoli and the respiratory zone is a series of cavities and tubes that move air to the conducting zone. the conducting zone moves oxygen into the cells and the respiratory zone takes carbon dioxide away from the cells. the conducting zone moves oxygen into the bloodstream and the respiratory zone takes carbon dioxide away from the bloodstream.

Coral reefs support more species per unit area than any other marine environment on earth. what is one way coral reefs are important to the health of the biosphere

Which of the following was not a major animal on land during the carboniferous period? amphibians insects both a and b none of the above