In geology, a key bed (syn marker bed) is a relatively thin layer of sedimentary
rock that is readily recognized on the basis of either its distinct
physical characteristics or fossil content and can be mapped over a very
large geographic area.[1]
As a result, a key bed is useful for correlating sequences of
sedimentary rocks over a large area. Typically, key beds were created as
the result of either instantaneous events or (geologically speaking)
very short episodes of the widespread deposition of a specific types of sediment. As the result, key beds often can be used for both mapping and correlating sedimentary rocks and dating them. Volcanic ash beds ( and bentonite beds) and impact spherule beds, and specific megaturbidites
are types of key beds created by instantaneous events. The widespread
accumulation of distinctive sediments over a geologically short period
of time have created key beds in the form of peat beds, coal beds, shell beds, marine bands, black in cyclothems, and oil shales. A well-known example of a key bed is the global layer of iridium-rich impact ejecta that marks the Cretaceous–Paleogene boundary (K–T boundary). Please let me know if it works.
Answer:
Molecules naturally disperse from areas of higher concentration to lower concentration.
As oxygen-rich (and carbon dioxide-poor) blood travels by a cell the oxygen diffuses through the cell membrane to the area of lower concentration inside the cell. It can do this easily because the oxygen molecule (O2) is very small and has no charge or polarity. The oxygen is used up rapidly by mitochondria. This rapid consumption causes oxygen to constantly move into the cell from the blood.
The mitochondria creates carbon dioxide (CO2) as a waste product of cellular respiration (the process that makes energy for your body). Because the CO2 is of a higher concentration in the cell than in the blood passing by, this gas continually diffuses out of the cell. It too is small and uncharged so it can pass through cell membranes easily.
These movements require no energy (in the form of ATP) on behalf of the cell.
Explanation:
B so happens to be the answer my friends
