root

• What are the two main types of flowering plants based on cotyledons?

  Monocotyledonous and Dicotyledonous
• What are the characteristics of roots?


  • Descending part
  • Non-green
  • No nodes and internodes
  • Buds and leaves usually absent
  • With root cap
  • Neutral/negative phototropic
  • Positive hydrotropic
  • Positive geotropic
• What type of root system is mainly found in monocots?


  Fibrous or diffuse root system
• Describe the fibrous root system.


  It consists of similarly sized, slender primary roots that grow shallow in the soil and send out smaller secondary roots.
• What type of root system is primarily found in dicots?


  Taproot system
• What is the structure of a taproot system?


  • Long and thick central primary root
  • Grows deep into the soil
  • Sends out smaller secondary roots
• What is the primary root formed from during germination?


  It is formed when the radicle elongates.
• What are secondary roots and where do they originate from?


  Secondary roots are branch roots that arise from the primary root and originate from the pericycle.
• What are adventitious roots?


  Adventitious roots do not develop from primary roots but arise from stems, leaves, or other plant parts.
• What are the functions of roots?


  • Anchor the plant in the soil
  • Absorb water and dissolved nutrients
  • Adapted for specialized functions in some plants
• What is the root cap?


  It is a thimble-shaped mass of parenchyma cells at the tip of each root that protects the root from mechanical injury.
• What is the role of mucigel released by dictyosomes in the root cap?


  Mucigel acts as a lubricant and protects the root cap.
• What is the quiescent center in the root tip?


  It is made up of 500-1000 mature cells arrested in G1 that can become active when meristematic cells are damaged.
• What are the regions of the root tip?


  1. Root cap
  2. Quiescent center
  3. Subapical region

  • Zone of cellular division
  • Zone of cellular elongation
  • Zone of cellular maturation
• What is the apical meristem responsible for in the root tip?


  It is responsible for cell division in the root tip.
• What is the function of the pericycle in roots?


  The pericycle is a meristematic layer that is involved in branch root formation.
• What are the components of the vascular tissue in roots?

  • Xylem
  • Phloem
  • Conjunctive parenchyma
• How does xylem differ in dicots and monocots?


  Dicots have protostelic xylem forming a lobed solid core, while monocots have siphonostelic xylem.
• What is primary growth in roots?


  • Growth in length
  • Occurs at the root tip
  • Involves apical meristem
• What is secondary growth in roots?


  • Growth in width
  • Involves lateral meristems (vascular cambium and cork cambium)
  • Found only in dicot roots
• From where do lateral roots arise in the stele?


  Lateral roots arise from the pericycle of the stele.
• What are some modifications of roots?

  • Food storage
  • Propagative roots
  • Pneumatophores
  • Aerial roots
  • Photosynthetic roots
  • Contractile roots
  • Buttress roots
  • Parasitic roots
  • Symbiotic roots (e.g., mycorrhizae)
• What is the mutualistic relationship in symbiotic roots of legumes?


  Legumes form root nodules with bacteria that fix atmospheric nitrogen for the plant.
• What is the role of mycorrhizae in symbiotic roots?


  Mycorrhizae form a partnership with plants to increase nutrient absorption and provide protection against pathogens.