Question

Assertion :Assertion : On stimulation, a muscle cell releases calcium Ions $\left(Ca{l}^{2+}\right)$ from sarcoplasmic reticulum. Reason: Reason : By reacting with a protein complex, $Ca{l}^{2+}$ uncover active sites on the actin filaments.

• A. If both assertion and reason are true and reason is the correct explanation of assertion.
• B. If both assertion and reason are true but reason is not the correct explanation of assertion.
• C. If assertion Is true but reason is false.
• D. If both assertion and reason are false.

Answer 1

The correct option is A If both assertion and reason are true and reason is the correct explanation of assertion.

The endoplasmic reticulum present in the muscles secrete the calcium ions that bind to the active site on the muscle fibre an actin filament.

Actin filaments are the thin filaments that are composed of 3 proteins. The active site is covered so the sliding does not occur. The calcium ion binds and uncovers its active site so the sliding movement takes place.

So, the correct option is 'If both assertion and reason are true and the reason is the correct explanation of assertion.'