Final answer:
The tension generated in a skeletal muscle fiber is directly proportional to the number of cross-bridges formed between actin and myosin. Cross-bridges can only form where thick and thin filaments overlap, allowing myosin to bind to actin.
Step-by-step explanation:
The tension generated in a skeletal muscle fiber is directly proportional to the number of cross-bridges formed between actin and myosin. Cross-bridges can only form where thick and thin filaments overlap, allowing myosin to bind to actin. If more cross-bridges are formed, more myosin will pull on actin, and more tension will be produced.