Geological change will not cause a mass extinction, because it happens on a too big scale - on the scale of millions of years. During such long time, it is more likely that other causes will influence the survival of extinction of species, such as climate change or environmental disasters, and even if there is a small influence, it would not be significant next to other causes.
Variation means difference in genetic makeup between individuals within a specie.
The velocity (speed) of a sound wave (any wave in fact) is related to its frequency and wavelength by the equation . This is easy to remember since it's a distance divided by a time because frequency is the inverse of the period.
Since for sound traveling through the given solid object we have that and , the speed of sound will be:
this is what i looked up and got
It is the nucleus that contains DNA and controls the functions of the cells
Only the bases varies from one nucleotide to another.