Q.What are stem cells? Explain its role in the field of medicine.

Step 1. Define stem cells: they are undifferentiated cells found in most multicellular animals, capable of undergoing repeated mitotic divisions while retaining their undifferentiated state (self-renewal), and possessing 'cellular potency' — the ability to differentiate into specialised cell types drawn from the three germ layers (ectoderm, endoderm, mesoderm). Step 2. Describe the two main mammalian types: embryonic stem (ES) cells, isolated from the epiblast of a blastocyst's inner cell mass, are pluripotent and effectively immortal in culture; adult (somatic) stem cells are found throughout life in various tissues (red bone marrow being a rich source), are mostly multipotent, and function as the body's built-in tissue-repair system. Step 3. Explain the medical role: stem cell research has the potential to revolutionise medicine because stem cells can regenerate damaged and diseased organs, meaning they can be used for cell-based therapies to replace or repair failing tissue; they are also used to test the safety and efficacy of new drugs on human cells before those drugs reach patients. Step 4. Mention the applied …

Define stem cells by their two defining properties (self-renewal and potency), describe the ES-cell/adult-cell distinction, and connect …

• Defining stem cells only as 'cells that can become other cells' without mentioning the equally essential self-renewal property. …