Question

What would happen if our backbone is made up of one single bone

Answer 1

our back bone can't move properly or break easily

Answer 2

$\huge\purple{Ello \: ♡}$

The structural composition of back bone allows us to bend, crouch, stand and lie down on the ground. The vertebral units promote this movement. If back bone is made up of one long bone then we would never be able to sit, crouch or lie. One single bone means no flexibility in the structure of a bone.