1. how is 0.00069 written in scientific notation? (1 point).
o 69x10--
06.9x104
o 0.69x107
0692104

Explanation:

When a number is written in scientific notation (representing the number using powers of base ten) it is expressed so that it contains a digit in the place of the units and all other digits after the decimal point, multiplied by the respective exponent.  

Then, the significant digits will be the digits that are before the power of ten.

In the case of  we have to move the decimal point to the right and the power of base ten will be equal to the spaces moved to the right:

dopamine..

"it was found that some people who were taking the drug l-dopa to raise their levels of dopamine were developing schizophrenic-like symptoms supporting research a strength of the dopamine hypothesis is that there are many studies which have shown support for the neurochemical explanation."