If rbcs carry oxygen, what does plasma carry?

Proteins, etc: Plasma is a yellowish liquid portion of whole blood after red blood cells, white blood cells and platelet are removed by centrifuge. It contains many proteins, hormones, and electrolytes essential for our life. For proteins, it includes immunoglobulin (for immunity), clotting factors (for hemostasis reducing bleeding), lipoproteins (carry lipid), enzymes and hormones, etc.