Chapter 10 Section 3 Quiz

In a sarcomere, the central portion of thick filaments are linked laterally by proteins of the

• Z line

• M line

• H band

• A band

• I band

The repeating unit of a skeletal muscle fiber is the

A) sarcolemma.

B) sarcomere.

C) sarcoplasmic reticulum.

D) myofibril.

E) myofilament.

Answer: B

• sarcolemma

• sarcomere

• sarcoplasmic reticulum

• myofibril

• myofilament

The plasma membrane of a skeletal muscle fiber is called the

• sarcolemma

• sarcomere

• sarcosome

• sarcoplsmic reticulum

• sarcoplasm

Muscle fibers differ from "typical cells" in that muscle fibers

• lack a plasma membrane

• have many nuclei

• are very small

• lack mitochondria

• have large gaps in the cell membrane

Which of the following best describes the term Z line?

• protein that accounts for elasticity of resting muscle

• repeating unit of striated myofibrils

• storage site for calcium ions

• thin filaments are anchored here

• largely made of myosin molecules

The skeletal muscle complex known as the triad consists of

• actin, myosin, and titin filaments.

• a transverse tubule and two terminal cisternae.

• filaments, myofibrils, and sarcomeres.

• A bands, H bands, and I bands.

• actin, myosin, and sarcomeres.

At rest, the tropomyosin molecule is held in place by

• actin molecules

• myosin molecules

• troponin molecules

• ATP molecules

• calcium ions

The region of the sarcomere that always contains thin filaments is the

• Z line

• M line

• H band

• A band

• I band

The series of membranous channels that surround each myofibril is the

• sarcoplasmic reticulum.

• sarcoplasm.

• sarcomere.

• sarcolemma.

• endomysium.

When a skeletal muscle fiber contracts, the

• H bands and I bands get larger.

• zones of overlap get larger.

• Z lines move further apart.

• width of the A band increases.

• All of the answers are correct.