Aggregation of Cells

• Classification of Plant tissues

  • Meristem(undergo division)
  • Permanent (Do not undergo division)
• Two tyoes of Permanent tissue

  • Simple Permanent tissue(made up of only one tyoe of cells)
  • Complex Permanent tissue(made up of many kinds of cells)
• Types of Complex Permanent Tissue

  • Xylem
  • Phloem
• Types of Simple Permanent Tissue

  • Parenchyma
  • Collenchyma
  • Sclerenchyma
• Types of Sclerenchyma

  Sclerenchyma Fibres

  Sclereids
• Characteristics of Meristem:

  • living,thin walled
  • rounded/polygonal
  • Compactly arranged (no intercellular space)
  • thin,elastic cell wall
  • dense cytoplasm with distinct nucleus
  • absent plastids and crystals,present proplastids, ribosome, mitochondria, E.R
• Where are meristem usually found?

  Found at the apices of root and shoot
• The growth by the activity of intrafascicular cambium is called secondary growth-increases the girth / thickness of plant
• Examples of secondary Meristem

  • Cork cambium/ phellogen
  • intrafascicular cambium
  • vascular cambium/interfascicular cambium
  • wood cambium
  • accessory cambium
• Classification of Meristem based on location

  1. Apical Meristem
  2. Intercalary Meristem
  3. Lateral Meristem
• The shoot meristem is terminal while the root apical Meristem is sub terminal, i.e., located below the root cap
• Structures of apical Meristem

  Shoot apical meristem

  Reproductive shoot apex

  Root apical Meristem
• What are the theories proposed for the development of shoot apex?

  Apical cell theory

  Histogen cell theory

  Tunica corpus theory
• What is a Quiescent centre?

  A region in the apical meristem of a root where cell division proceeds very slowly or not at all
• What is the significance of quiescent centre?

  It acts as a reservoir. It ensure the regeneration and persistence of the root apical meristem.
• why is root apex subterminal?

  Due to the presence of root cap(calyptra)
• Characteristics of Parenchyma

  Living, isodiametric,thin walled oval/polygonal/spherical cells

  Present intercellular space b/w cells which are filled with air
• Types of Parenchyma

  Epidermal parenchyma

  Chlorenchyma(Palisade & spongy)

  Aerenchyma

  Prosenchyma

  Xylem and phloem parenchyma

  Idioblast

  Succulent parenchyma
• Use of succulent parenchyma

  Storage of water