You notice a buildup of dark clouds and shifting winds. what is likely?

If we observe a buildup of very dark color clouds and the gradual shifting of wind direction, then it should be clear that a severe weather condition is approaching, which might result in either thunderstorms or heavy rainfall, most probably with lightning.

               This could be due to the existence of a cold front where the warm air is removed by rising up, and results in the drop of temperature.

the answer is: the „power stroke“ step.

muscle contraction can be divided into a few steps:

1. the release of ach (acetylcholine) in the synaptic cleft, binding of ach for its receptor and consequently opening of the ca channels.

2. the release of ca, binding of ca for the troponin

3. troponin shifting the tropomyosin, which was blocking the active site on the actin

4. myosin heads attaching to actin by breaking down atp to adp+ pi

5.   formation of the ‘cross-bridge’ on the active site of the actin filament by myosin head

6. “power stroke” -the cross bridge pulls actin, which slides over the myosin

9.     7. the release of adp completes the cross-bridge movement and atp attaches to myosin, breaking the actin-myosin cross bridge.