Muscle Contraction MCQs for Biology

Which protein interacts with actin to cause muscle contraction?

• Tropomyosin

• Myosin

• Troponin

• Titin

The smallest unit of muscle that contracts is called:

• Muscle fiber

• Sarcomere

• Myofibril

• Tendon

Which ion is needed for muscle contraction?

• Sodium (Na+)

• Potassium (K+)

• Calcium (Ca2+)

• Magnesium (Mg2+)

ATP is needed in muscle contraction to:

• Make muscles relax

• Detach myosin from actin

• Store calcium ions

• Make new muscle fibers

The sarcoplasmic reticulum helps muscle contraction by:

• Producing energy

• Releasing calcium ions

• Supporting muscle fibers

• Transmitting nerve signals

During muscle contraction:

• Actin shortens

• Myosin shortens

• Sarcomeres shorten

• Muscle fibers get longer

What binds to troponin to start muscle contraction?

• ATP

• Calcium ions

• Magnesium ions

• Sodium ions

Which part of the sarcomere stays the same length during contraction?

• A band

• I band

• H zone

• Z line

In a resting muscle, the actin binding sites are covered by:

• Troponin

• Tropomyosin

• Myosin heads

• Calcium ions

Which molecule provides energy for muscle contraction?

• Glucose

• ATP

• Creatine phosphate

• Fatty acids