Stem cells

• Stem cells: unspecialised cells that can divide into specialised cells to replace damaged cells or cells that can't divide
• Bone marrow

  Blood cells
• Meristem

  Xylem

  Phloem

  Vascular cambium cells that produces these
• Erythrocytes

  • Flattened biconcave - increases surface area to volume ratio
  • Flexible - squeeze through narrow capillaries
  • No nuclei - more space for haemoglobin/oxygen
• Neutrophils

  • Flexible shape - allows them to engulf pathogens
  • Many lysosome - break down pathogens
• Sperm cell

  • Flagellum - move
  • Mitochondria - energy
  • Acrosome - penetrate surface of egg
• Epithelial cells

  • cilia - waft particles away
  • squamous - thin efficient exchange of gas
• Palisade

  • chloroplast - absorb sunlight
  • thin - CO2 easily diffuse into cell
• Root hair cell

  • Large surface area - absorption
  • thin permeable cell
  • mitochondria - active transport
• Tissue: A group of cells that work together to carry out a specific function.
• Organ: A group of tissues that work together to perform a specific function.
• Organ system: A group of organs that work together to perform a specific function.
• Cells: The basic unit of life that can carry out all the functions of life.