Question

Striated muscle has light and dark bands. The light bands are called ________, whereas the dark bands are called ________.

A) Z lines; M lines
B) H zones; M zones
C) A bands; I bands
D) I bands; A bands
E) M lines; A bands

Answer 1

The light bands in striated muscle are called I bands, and the dark bands are called A bands, so the correct answer is D) I bands; A bands.

Step-by-step explanation:

Striated muscle has light and dark bands. The light bands are called I bands, whereas the dark bands are called A bands. Therefore, the correct answer is D) I bands; A bands. The striated appearance of skeletal muscle tissue is due to repeating bands of the proteins actin and myosin that are present along the length of myofibrils. Dark A bands and light I bands repeat along myofibrils, and the alignment of myofibrils in the cell causes the entire cell to appear striated or banded. Each I band has a dense line called a Z disc or Z line, and the space between two consecutive Z discs is called a sarcomere, which is the functional unit of skeletal muscle.