What structure is in the red circle? 

Name one of the gasses which flow through the opening the red arrow is pointing to.  

Identify the type of root system found below.

What structure is the arrow pointing to?

What structure is the arrow pointing to? 

What is your favorite plant?

Depolarization of the ventricles is represented on an electrocardiogram by the  

If the connection between the SA node and AV node becomes blocked,  

CD8 markers are to ________ T cells as CD4 markers are to ________ T cells.  

Blood returning to the heart from the pulmonary circuit first enters the