What are two examples of environmental events that have caused mass extinctions?

What is the next step in muscle contraction after the actin changes shape? (apex)

Name the two stages involved in protein synthesis and explain what occurs in each of the two stages. be sure to also indicate where each process takes place. plz don't give one sentence answers : d

Which situation is an example of not doing work? lifting a couch throwing a baseball running up stairs carrying a box