Each state of the United States selects two senators to represent their states in the United States Senate. In 1913, the 17th Amendment[?] to the United States Constitution provided for the direct popular election of senators; prior to this, senators were selected by state legislatures.
... which is then captured by a primary acceptor protein.
The chlorophyll's electron can follow either of two different pathways, cyclic or non-cyclic.
Cyclic ...