Because of the phloem or tube like structures
If your blood contains dissolved food, you are in BIG trouble, but only for a moment... after a moment you will be dead. The blood brings glucose to the cells, and the cells extract energy from the glucose. This is the most basic energy form for the cells; there are others.
Water is needed by all plants to carry nutrients from the soil to the cells and transport waste products away from the cells through a process called transpiration. Water also helps plants maintain their structure and turgidity.
water
blood
hemoglobin.
Iron filings can't be dissolved in water, but, over time iron filling in water will rust away.
Hemoglobin
Blood carries carbon dioxide out of cells.
artery
no
To carry oxygen and nutrients to the cells of the body, and to carry toxins and waste products away from them.
the blood cells help it from getting discinigrated.