1. Which protein mainly forms the thick filament of a skeletal muscle sarcomere?
A.
Actin
B.
Myosin
C.
Troponin
D.
Tropomyosin
Correct Answer:
Myosin
Explanation:
Thick filaments are primarily made of myosin molecules.
2. What is the globular part of a myosin molecule called?
A.
Myosin head
B.
Myosin disc
C.
Myosin ring
D.
Myosin plate
Correct Answer:
Myosin head
Explanation:
Each myosin molecule has a globular head that projects from the thick filament.
3. Which part of the myosin head binds to actin during muscle contraction?
A.
Actin-binding site
B.
Z-line site
C.
Troponin site
D.
Titin site
Correct Answer:
Actin-binding site
Explanation:
The myosin head contains an actin-binding site that allows it to attach to actin during contraction.
4. Which activity is present in the myosin head?
A.
ATPase activity
B.
DNA polymerase activity
C.
Peptidase activity
D.
Lipase activity
Correct Answer:
ATPase activity
Explanation:
The myosin head has ATPase activity and uses energy from ATP during muscle contraction.
5. In a sarcomere, thick filaments are mainly located in which band?
A.
I band
B.
A band
C.
Z band
D.
H zone only
Correct Answer:
A band
Explanation:
The A band corresponds to the length of the thick filaments, including regions where they overlap with thin filaments.
6. The central region of a thick filament where myosin heads are absent is called the:
A.
Bare zone
B.
Z line
C.
I band
D.
Terminal disc
Correct Answer:
Bare zone
Explanation:
The bare zone is the central part of a thick filament that lacks projecting myosin heads.
7. Myosin molecules in a thick filament are arranged mainly in which pattern?
A.
Random pattern
B.
Bipolar pattern
C.
Single-layer pattern
D.
Circular pattern
Correct Answer:
Bipolar pattern
Explanation:
Myosin molecules are arranged in a bipolar manner, with their tails toward the center and heads directed outward.
8. Which part of myosin forms the long central portion of a thick filament?
A.
Myosin tail
B.
Myosin head
C.
Actin-binding site
D.
ATP-binding pocket only
Correct Answer:
Myosin tail
Explanation:
The long tails of myosin molecules associate to form the main shaft of the thick filament.
9. What do the projecting myosin heads of a thick filament form during contraction?
A.
Cross-bridges
B.
Z lines
C.
Sarcomeres
D.
T tubules
Correct Answer:
Cross-bridges
Explanation:
Myosin heads project from the thick filament and form cross-bridges when they attach to actin.
10. Which molecule provides energy that is used by the myosin heads of thick filaments?
A.
ATP
B.
DNA
C.
Glucose only
D.
Oxygen only
Correct Answer:
ATP
Explanation:
Myosin heads use energy released from ATP hydrolysis to perform their role in contraction.
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