The earth's atmosphere is divided into several layers, namely-
(1) Troposphere
(2) Stratosphere
(3) Mesosphere
(4) Thermosphere
The troposphere is the layer that extends up to a height of about 10 km from the ground surface. In this layer. the temperature decreases with altitude. This is the layer in which all the weather phenomenon takes place. The Oxygen gas this available in this layer that is required by all the living organisms to exist on earth. It also regulates the earth's atmospheric temperature.
Thus, the troposphere is one of the most important layer of atmosphere.
Simple diffusion does not require energy or need the assistance of a transport protein. Other larger or charged molecules that diffuse across a membrane may need assistance from a protein.
Mitochondria have an important role in cellular respiration through the production of ATP, using chemical energy found in glucose and other nutrients. Mitochondria are also responsible for generating clusters of iron and sulfur, which are important cofactors of many enzymes
