Mantle convection describes the movement of the mantle as it transfers heat from the white-hot core to the brittle lithosphere. ... Convection currents also transfer denser, cooler material from the crust to Earth's interior through the process of subduction.Aug 11, 2015
That would be peptide bonds
The Precambrian era envelopes the major bulk of the history of the Earth, beginning from the creation of the planet approx 4.5 billion years ago and terminating with the origination of composite, multicelled forms of life approximately 4 billion years after.
The Precambrian refers to the earliest of the geologic ages that are signified by the distinct layers of sedimentary rock. The Earth was about more than six hundred million years old when life started. The planet had cooled down from its native molten state, creating a solid crust and oceans formed by water vapor in the atmosphere.
At about three billion years ago, the atmosphere of the Earth was virtually devoid of oxygen. At approximately 2.4 billion years ago, oxygen was discharged from the seas as a waste product of photosynthesis by cyanobacteria. The levels of the gas slowly raised, attaining about 1 percent around two billion years ago.
Approximately 800 million years ago, the levels of oxygen attained about 21 percent and started to breathe life into more composite species. The oxygen-rich ozone layer was also created, protecting the surface of the Earth from the harmful solar radiation.
In Newton's Third Law of Motion, when one object exerts a force on a second object, the forces are equal in magnitude and opposite in direction. The correct answer is B.
At the time of this writing, the most recently available statistics pertain to 2010, at which point the World Bank reported that about 37.7 percent of the world's total land area was considered agricultural land, while approximately 10.6 percent was considered arable.
