This depends on three things;
1) The type of defect, if it was a manufacturers defect (it just stopped working) and not abuse, the it probably will be covered.
2) The type of coverage the extended warranty covers
; i.e. does it cover
all components or just the main board and hard drive (I`ve seen these types of deceptive "extended warranties" before), some warranties specifically don`t cover
the power adapter, battery and LCD screen
. You need to read your warranties fine print.
3) The time line of coverage from the extended warranty
. Some extended warranties only kick in after the original manufacturers warranty
has run out. If that is the case with your warranty
, and you are still within the manufacturers warranty
, they will refer you to the manufacturer (Apple).
In any of these cases, you need to read up on what your warranties cover
and what they won`t.