Final answer:
In a sarcomere, the Z discs mark the boundaries, and the letters used to label the elements are Z line, I band, A band, H zone, and M line. The I band has a Z disk in the middle. The darkest band is the A band because it contains overlapping thin and thick filaments. The Z discs form the boundaries of a sarcomere, while the M line divides the A band in half and provides structural integrity.
Step-by-step explanation:
List of letters used to label the elements of a sarcomere:
Z line
I band
A band
H zone
M line
Which band has a Z disk in the middle?
The I band has a Z disk in the middle.
Which is the darkest band? Why?
The A band is the darkest band because it contains overlapping thin and thick filaments (actin and myosin).
Which element forms the boundaries of a sarcomere?
The Z discs (Z lines) form the boundaries of a sarcomere.
Name the line that divides the A band in half. What is the function of this line?
The line that divides the A band in half is called the M line. The function of this line is to provide structural integrity to the sarcomere and help stabilize the movement of the thick filaments during muscle contraction.