To be effective, percutaneous transluminal coronary angioplasty (ptca) must be performed within what time frame, beginning with arrival at the emergency department after diagnosis of myocardial infarction (mi)?

This procedure needs be performed within 60 minutes time frame.
This commonly known as "door-to-balloon. 
Granting entry to  the blood in order to circulate unobstructed to the heart muscle, the PTCA is less invasive procedure to open up blocked coronary arteries.

The name of the instrument that the scientist uses is called a microscope.a microscope is used to view objects which is not visible to the naked eyes

Leaves specifically the gas exchange between plants and the environment. while plants undergo photosynthesis, they also partake in cellular respiration. respiration is the process that happens in the leaves of plants.