Question

question 3
cross bridges form between:
a actin and myosin
b actin and tropomyosin
c troponin and tropomyosin
d myosin and troponin
e actin and troponin

Explanation:

In muscle contraction, cross - bridges are formed between actin (a thin filament protein) and myosin (a thick filament protein). Myosin heads bind to actin to create cross - bridges. Tropomyosin and troponin are regulatory proteins. Tropomyosin covers the binding sites on actin in a relaxed muscle, and troponin helps in the regulation of this process by binding to calcium ions. So, cross - bridges do not form between actin and tropomyosin (B), troponin and tropomyosin (C), myosin and troponin (D), or actin and troponin (E).

Answer:

A. actin and myosin