In a few generations, this population of beetles changed. A group of bugs includes 13 black bugs and 4 green bugs. After a few generations, there are 13 green bugs and 4 black bugs.

Which is the most likely explanation for the change?
The beetle population moved to a greener habitat.
A natural disaster almost caused the extinction of the population.
The beetle population’s food sources decreased dramatically.
A mutation resulted in a new color of ins

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.