Explain how you can use a straightedge and a compass to construct an angle that is both congruent and adjacent to a given angle.

Given an angle ABC (with the center in B), you should put the compass with the center in B and make an arc with a length that is more than the double of the angle. There you have the intersections between the arc and the segments BA and BC - let's call the intersections D and E. You should open the compass from D to E and make an arc starting in D which intersects the previous arc - let's call that intersection F. Now you should draw a segment (using the straightedge) which starts in B and passes through F and ends in a new point -let's call that one G- with a length similar to AB and BC. So now you have the angle ABG (with center in B) which is adjacent and congruent to ABC.

Centriole.centrioles are present in animal cells but are usually absent in plant cells.