According to cell theory, flowers, blood, bacteria and skin are made of cells. The cell theory states that; All living organisms are made up of cells (unicellular or multicellular), the cell is the basic unit of life and cells come from pre-existing cells.
Cells are the smallest and basic structural and functional unit of all living organism. Cells are usually microscopic and may be eukaryotic (cells with a true nucleus) or prokaryotic (cells that lacks a true nucleus).
Flowers are living organisms (plants) and are made of cells. Blood is a specialized body fluid that is composed of cells. Also, bacteria and skin are made of cells.