Question

Consider the following statements:

[(a)] The banded appearance of the sarcomere is due to difference in the size and density of thick and thin filaments.
[(b)] The A band is the area containing thick filaments.
[(c)] A band includes the M line, the H band and the zone of overlap (thick and thin filaments).
[(d)] A band and I band are anisotropic and isotropic, respectively.
The incorrect statements are:

• A. a, b and c
• B. b and c
• C. b, c and d
• D. None

Hint:

A band = thick filaments (anisotropic, dark) I band = thin filaments (isotropic, light)

Answer 1

The Correct Option is D

Step 1: Statement (a) is correct. The striated (banded) appearance of a sarcomere is due to differences in the thickness, size, and density of actin (thin) and myosin (thick) filaments.
Step 2: Statement (b) is correct. The A band corresponds to the region occupied by thick (myosin) filaments.
Step 3: Statement (c) is correct. The A band includes:

M line (center),
H zone (region with only thick filaments),
Zones of overlap between thick and thin filaments.

Step 4: Statement (d) is correct.

A band is anisotropic (dark band),
I band is isotropic (light band).

Step 5: Since all statements (a), (b), (c), and (d) are correct, there are no incorrect statements.