1. Which band in a sarcomere is known as the dark band?
A.
A band
B.
I band
C.
Z line
D.
H zone
Correct Answer:
A band
Explanation:
The A band appears dark because it contains thick myosin filaments, along with regions where actin and myosin overlap.
2. Which type of filament is present throughout the length of the A band?
A.
Actin filament
B.
Myosin filament
C.
Troponin filament
D.
Tropomyosin filament
Correct Answer:
Myosin filament
Explanation:
The A band corresponds to the entire length of the thick myosin filaments.
3. What happens to the length of the A band during muscle contraction?
A.
It becomes longer
B.
It becomes shorter
C.
It remains constant
D.
It disappears completely
Correct Answer:
It remains constant
Explanation:
During contraction, the A band maintains a constant length because the myosin filaments do not shorten.
4. The A band contains which arrangement of muscle filaments?
A.
Only thin actin filaments
B.
Only thick myosin filaments
C.
Thick myosin filaments and regions of actin overlap
D.
Only Z lines
Correct Answer:
Thick myosin filaments and regions of actin overlap
Explanation:
The A band includes the full length of myosin filaments and the areas where actin filaments overlap them.
5. Which band remains unchanged in length when a sarcomere contracts?
A.
A band
B.
I band
C.
Z line
D.
Thin filament region
Correct Answer:
A band
Explanation:
The A band remains unchanged because contraction involves sliding of filaments rather than shortening of the myosin filaments.
6. The width of the A band is mainly determined by the length of which structure?
A.
Thin actin filaments
B.
Thick myosin filaments
C.
Z lines
D.
Sarcolemma
Correct Answer:
Thick myosin filaments
Explanation:
The A band extends over the length of the thick myosin filaments, so its width is mainly determined by them.
7. Which statement correctly describes the A band in a skeletal muscle sarcomere?
A.
It is the light band containing only actin
B.
It is the dark band associated with myosin
C.
It is the boundary between two sarcomeres
D.
It contains no contractile proteins
Correct Answer:
It is the dark band associated with myosin
Explanation:
The A band is the darker region of a sarcomere and is associated with the thick myosin filaments.
8. During contraction, the A band does not change because the thick filaments:
A.
Break apart
B.
Move out of the sarcomere
C.
Maintain their length
D.
Change into thin filaments
Correct Answer:
Maintain their length
Explanation:
The thick myosin filaments maintain their length during contraction, so the A band also remains constant.
9. Which region includes the parts where actin and myosin filaments overlap?
A.
A band
B.
Z line only
C.
I band only
D.
Sarcolemma
Correct Answer:
A band
Explanation:
The A band includes the regions of overlap between thin actin and thick myosin filaments.
10. In a relaxed sarcomere, the A band is best identified as the region that:
A.
Contains the length of the myosin filaments
B.
Contains only the space between Z lines
C.
Has no thick filaments
D.
Contains only connective tissue
Correct Answer:
Contains the length of the myosin filaments
Explanation:
The A band extends across the entire length of the thick myosin filaments in the sarcomere.
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