Which valve prevents blood to flow from the right atrium to the right ventricle

How did the research presented in the article affect scientists' understanding of the evolution of eukaryotes

What is the statement plant growth is affected by the color light

Some tools have graduations to show multiple measurements. for example, a ruler may have graduations for both millimeters and centimeters. when measuring the length of an earthworm, which graduations would allow for the most accurate measurement? millimeters centimeters decimeters meters