Lecture 10 Flashcards
Name the parts of the root
•Epidermis
•Cortex
•Vascular tissues
What is the dermal tissue of the root system called
Epidermis
•Outermost layer of cells, like the skin of the root
What is the ground tissue system of the root system called
Cortex
•Tissue inside epidermis that stores starch and other substances for the growth of the root; it is made out of parenchyma tissue
Write a short note on the vascular tissue system
•In most roots, the vascular tissues form a central cylinder, but in some monocotyledons they form a hollow cylinder around a central pith
Function of the Xylem
•carries the water taken in by the root hairs and epidermis up the plant to the stems and leaves
Function of the Phloem
•carries the food produced by the leaves down to the roots to be stored in the cortex
Write a short note on the endodermis
•the inner boundary of the cortex; one cell layer thick; controls the movement of water and minerals into the xylem and phloem
Write a short note on the Pericycle
•a layer found inside the endodermis which may produce lateral roots
•also produces vascular cambium in dicots
What’s different about endodermis and cortex
the endodermis lacks air spaces and the cell walls contain suberin in a band (the Casparian strip) that extends around the radial and transverse cell walls, which are perpendicular to the surface of the root.
What is the pericycle composed of
•parenchyma cells with primary walls but these may develop secondary walls as the plant ages.
•Lateral roots arise in the pericycle.
Name the external root anatomy parts
• Root cap
• Region of cell division
• Region of elongation
• Region of differentiation or maturation
Name the major zones of root development
• Region of cell division
• Region of elongation
• Region of differentiation or maturation
Write a short note on the region of cell division
•this is where the cells start to divide through mitosis
Where is the apical meristem located
Region of cell division
Write a short note on the region of elongation
•in this area just above the apical meristem, cells become longer and wider
• This action helps to push the root tip through the soil
Write a short note on the region of Maturation
•at this point, the cells become specialized, or
differentiated, taking on specific primary functions
• For example, the development of root hairs, xylem, phloem,
Where does cell division occur
At the tip of the root
When does root growth occur
• Root growth occurs when cells in the meristem extend in the elongation zone
What is elongation driven by
• Elongation is driven by hydrostatic pressure within the cells pushing the root tip further down the soil profile
Where do root hairs form
Maturation zone
Which parts of the root are furthest from the root tip
The oldest parts
Write a short note on the apical meristem
•found at the root tip, is where new cells develop
• It is covered by the root cap – protects it from damage as it passes through coarse soil particles
In the apical meristem how many times do cells divide per day
Once or twice a day
What does the transitional meristem arise from
The tips of roots and shoots
What forms the epidermis
The Protoderm
What forms the ground tissue
The ground meristem
What forms the primary phloem and xylem
The Procambium
What forms the vascular cylinder
Procambium
What forms the cortex
Ground meristem
What does the vascular cylinder contain
- Xylem=transports water and soluble nutrients from roots to shoot
- Phloem = transports sugars from photosynthesis to roots
Write a short note on the region of maturation or differentiation
• root hairs develop as protuberances from epidermal cells
• increase the surface area for the absorption of water
• cuticle exists on root but not on root hairs
Write a short note on root hairs
• Root hairs are outgrowths from the epidermis
•They have a high surface area:volume so increase the root surface area in contact with the soil
• Their capacity to absorb water and nutrients is huge, their small diameter
means they can fit between small pores
•They are short-lived (days), so die back and the older parts of the root would be hairless
Write a short note on the root cap
• The root cap is a cone of cells which protects the meristem and secretes mucilage
• The root cap protects the root as it pushes through the soil
• Root cap cells are constantly sloughed off
• The mucilage provides an environment for bacteria and fungi which live in the rhizosphere (the immediate environment of the root)
