The first known single-celled organisms appeared on Earth about 3.5 billion years ago, roughly a billion years after Earth formed. More complex forms of life took longer to evolve, with the first multicellular animals not appearing until about 600 million years ago.
Answer: lower atmospheric pressure
Explanation:
During the inspiration process the diaphragm, and external intercostal muscles. The contraction of the diaphragm causes the increase in the size of the thoracic cavity this causes the contraction of the external intercostal muscles. As a result of this the ribs and the sternum get elevated.
This causes the lungs to expand, and increasing the volume of the air passage. In this response the air pressure inside the lungs reduces below the air outside the body. Thus this facilitates the movement of the gases from a region of high pressure to low pressure, this way the air rushes into the lungs.
energy generated in ways that do not deplete natural resources or harm the environment, especially by avoiding the use of fossil fuels and nuclear power.
There's no land at the North Pole Instead it's all ice that's floating on top of the Arctic Ocean. ... Multi-year ice is thicker and has survived at least one melt season, whereas first-year ice is much thinner. Arctic sea ice usually reaches its minimum around mid-September each year.
