[填空题]
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1.Identify the part of the cells labelled A and B.
arrow points to the nucleus; arrow points to the plasma membrane
2.Outline why blood is classified as a tissue.
3.State where the stem cells needed to produce red blood cells are located.
4.Progenitor cells are produced by dividing stem cells. These cells will eventually differentiate even further. Blood cells have a common progenitor cell. Describe the process that happens to these progenitor cells.
