The lack of color signifies purity and innocence. The novice has no knowledge of tae kwon do.
The following is the requirements for testing for 9th Gup (Yellow Stripe)
Blocks: Down Block, Rising Block, Middle Block, Knifehand Block, Inside Forearm Block
Kicks: Front Snap Kick, Round House Kick, Side Thrust Kick (In Place)
Strikes: Single Punch, Cross Body Punch (to Head)
Stances: Front Stance, Back Stance, Side (Straddle) Stance
Form: Ki-Bon