Which of the following is the correct sequence of events for muscle contractions? a) motor neuron action potential, meurotransmitter release, muscle cell action potential, release of calcium ions from sr, atp-driven power stroke, sliding of myofilamentsb) neurotransmitter release, muscle cell action potential, motor reuron action potential, release of calcium ions from sr, sliding of myofilaments, atp-driven power strokec) muslce cell action potential, neurotransmitter release, atp-driven power stroke, calcium ion release from sr, sliding of myofilamentsd) neurotransmitter rlease, motor neuron cation potential, muscle cell action potential, release of calcium ions from sr, atp-driven power stroke

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.

answer:

the water molecules are transferred from the roots to the stem or top parts of the tall tree because of important properties of water which are adhesion, cohesion and capillary action. cohesion is the property of water molecules keeps water molecules in a combined state by sharing of bonds between them at the atomic level. adhesion allows the interaction of water molecules with other substances or substrate. adhesion will cause the attachment of water molecules to the wall of the vessel (xylem) of the plant. capillary action occurs when the adhesive force to the vessel wall is stronger than the cohesive force between water molecules. capillary action mimics the transfer of water from a tube or pipe. in this way water utilizes its property to transfer water from down to top level of the plant.