Bass guitarists often use a technique of playing riffs against a chord progression. A riff is a pattern of notes that is repeated throughout a progression (or song).
The one bar riff in example 42 is in the key of A and uses the arpeggio playing style. Memorize the finger pattern so that you can transfer it onto the 12 bar progression below.
You have probably heard this riff style of playing before. Play some recordings (fifties rock and roll or blues songs would be best) and listen to the bass.