Module 10 - Roots Flashcards
Root Tissues
Epidermis
Cortex
And Stele
Root origin
Embryonic Root - RAM
Adventitious Root - pericycle, endodermis, stem, leaf
Functions such as
anchorage, absorption,
and transport of minerals and water and storage of photosynthate were
established
Roots
Rhizoids vs ROOTS
Rhizoids from epidermis, roots from vascular tissue
root-like filaments growing out of epidermal cells of non-vascular plants particularly, bryophytes, which are useful in anchoring in place and absorbing nutrients and water
Rhizoids
Arise from vascular plants, ferns, and fern allies, gymnosperms, and angiosperms, always multicellular
Roots
Slow gravitropism is present in?
Basal Vascular plant species
Fast root gravitropism is present in
More recent common ancestor of the gymnosperms and angiosperms (seed plants)
Cells used for detection of gravitropism
Statocytes
Three types of roots
Tap
Fibrous
Adventitious
Hierarchy of roots
Primary->1st order->2nd Order->3rd order
Roots found surrounding the base just above the seminal roots
Brace roots
Roots larger than the adventitious roots to one side
Crown Roots
Other term for primary roots
Seminal Roots
Structural Adaptations of Roots
Larger plants address anchorage challenges with tap root systems, while smaller ones use fibrous roots.
Roots adapt with absorptive hairs and Casparian strips preventing nutrient backflow.
Subepidermal exodermis, like endodermis, limits apoplastic water loss in drought.
Mycorrhizal associations aid nutrient absorption, especially phosphorus, in mineral-deficient areas.
o innermost layer of cortex
o present in ALL roots and Dicot stems only
Endodermis
o outer layers of cortex
o roots of many plants especially majority of the Angiosperms
Exodermis
T/F Both exodermis and endodermis are ground tissues with casparian strips lined with suberin
F, endodermis lang
What is the innermost portion of the cortex
Endodermis
Outermost portion of the cortex
Exodermis or hypodermis
What are the functions of the casparian strip?
Prevents unimpeded apoplastic movement into the stele.
Prevents backflow of ions that entered symplastically into the stele.
Offers protection against pathogen invasion and potential root drying during stress.
Waterproofs the endodermal cell walls
Pathway wherein materials pass through the cell through the plasmodesmata
Symplastic Pathway
Pathway where the materials pass through the interconnected cell wall spaces
Apoplastic pathway
Functions of Root Cap
- Mechanical Protection
- Secretory Function
- Gravity Perception
New root cap cells, originating from the meristem, move outward over time, eventually shedding as the roots extend into the soil.
Mechanical Protection
Functions as an immune defense mechanism through the repulsion and killing of microbial pathogens
Root Extracellular Trap
Amyloplastids in statocytes that serve as sensors of gravity
Statoliths
T/F Roots can be endarch
False, all ROOTS ARE EXARCH
T/F In lateral root development, the pericycle divides both peri and anticlinally forming a root primordia while endodermis divides only anticlinally to protect the root primordia
True
