Prevents blood movement from left ventricle to left atrium

Astudent is looking through a microscope at some cells of an onion root tip. many of these cells are undergoing division since the root tip grows quickly and requires more cells. which cell most recently underwent metaphase? w x y z

What would happen if the tubing with the yellow band was placed in a beaker of distilled water?

Describe your dna model. which part do the straws represent? the pushpins? the paper clips and the black dots you made with the marker?