Sliding filament theory can be best explained as
- actin and myosin filaments do not shorten but rather slide past each other
- when myofilaments slide past each other, myosin filaments shorten while actin filaments do not shorten
- when myofilaments slide past each other actin filaments shorten while myosin filaments do not shorten
- actin and myosin filaments shorten and slide past each other.
Answer
(1) actin and myosin filaments do not shorten but rather slide past each other
Solution
As per NCERT, contraction of a muscle fibre takes place by the sliding of the thin (actin) filaments over the thick (myosin) filaments.
During contraction the length of the A band is retained and the I bands get reduced, i.e. the filaments themselves do not shorten.
∴ Actin and myosin filaments do not shorten but slide past each other.
Answer: (1)