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.
... non-cyclic.
Cyclic photophosphorylation
In cyclic electron flow, the electron originates in a pigment complex called photosystem I, passes from the primary acceptor ...