Question

What is the term that describes the unit of a muscle cell that contains all of the structures necessary to cause contraction?

Answer 1

Sarcomere.

Explanation:

Sarcomeres are the small contractile repeated units of the myofibril.
Sarcomere is a region of myofibril between two successive Z-lines. It contain H-zone, M-line. It also contain series of dark bands(A-band) and light bands(I-band).

• Thick filament extends across entire length of A band
• Thin filament extend across the I-band and partly into A-band.
  These are the filaments which have basic role in contraction and these are present in a sarcomere.

https://www.unm.edu/~lkravitz/Exercise%20Phys/musclesarcomere.html

Hope it helps...