Describe the sliding filament model of muscular contraction

Earth is tilted on its axis. which of these would not exist if earth had no tilt?

Aprimary producer stores 9,000 kcal. in the energy pyramid, if a primary producer is consumed by a first-level consumer, and that first-level consumer is consumed by a second-level consumer and the second-level consumer is consumed by a third-level consumer, how much energy is stored by the third-level consumer from the primary producer? *

Through which structure do the sperm travel to exit the testes?