Which of the following is most accurate when discussing the sliding filament theory?
1. Nerve impulse (action potential) arrives at the neuromuscular
junction triggering the release of the neurotransmitter acetycholine
2. Sodium binds to the protein troponin which is located on the actin
myofilament
3. When energy (ATP) is released, troponin slides over actin and the
muscle shortens
4. Actin heads bend (cross bridge) to attached to the exposed binding
sites on the myosin myofilament

Why are carbon dioxide concentrations expected to increase? a carbon dioxide concentrations are expected to increase, because fossil fuel burning is expected to increase b. carbon dioxide concentrations are expected to increase, because of an increase in agriculture. c.carbon dioxide concentrations are expected to increase, because more land will have to be cleared for increasing populations and agricultural use. d. all of the above select the best answer from the choices provided mark this and return save and exit next submit submit