How many beats is a crochet worth?

I believe you mean "crotchet" which is a British musical term for quarter note. In 4/4 (common) time it receives one beat.

quaver = eighth note; semi-quaver = sixteenth note.

minims = half notes (two crochets); semibreves = whole-notes (four crotchets)

source: http://www.shanemcdonald.org/music/learn-types-of-music-notes.html