Relationship between bit depth and dynamic range?
More bits mean more possible values for each channel. So each channel in an 8 bit image has 256 possible values, from 0 to 255, while a 10 bit channel has 4 times as many: 0 to 1024.

Dynamic range however is the range between the brightest sample a sensor chip can encode and the darkest - it is a property of the sensor. So you could conceivably have an 8 bit sensor with a wider dynamic range than a 10 bit sensor if it could resolve very bright and dark images, it would just have fewer steps between these than a 10 bit sensor with the same dynamic range.