I believe it is gene sex chromosones...
Organelle,
Cells,
Tissues,
Organs,
Organ System,
Organisms,
Populations,
Communities,
Ecosystems,
And Biosphere
Answer:
I would choose c
Explanation:
Please put me under brainliest?!
The answer is; A
When an impulse from the motor neuron reached the neuromuscular junction, the voltage-dependent calcium channels are activated and the neurotransmitter released from the presynaptic cleft. When the neurotransmitter binds to their receptors on the sarcolemma, the muscle fibers become depolarised; the calcium is released from their vesicles. The Ca2+ ions are important in the power stroke because they bind to troponin. Upon binding calcium, troponin moves tropomyosin away from the myosin-binding sites on actin. Powered by the energy from ATP molecule, the myosin is able to bind on the actin and slides over the actin filament.
