Plant Tissue System Flashcards
In what do changed occur in a cell during cell differentiation?
Changes in
Cytoplasm
Organelle
Cell wall
What are the three main tissue systems of vascular plants
Dermal tissue system
Ground tissue system
Vascular tissue system
What is the outer protective covering if plants
Dermal tissue system
What is an example for dermal tissue system
Epidermis
What are the characteristics of epidermis
- Tightly packed single cell layer
- Protective layer in stems and roots of primary plant body and leaves
- Normally covered by a cuticle
- Specialized cells such as guard cells and trichomes and root hairs are found .
What is cuticle
A waxy epidermal coating in aerial parts
Functions if epidermis
-Defence against pathogens
-Cuticle help prevent water loss
-Root hair involve in absorption of water and mineral ions
-Gaurd cells help in gaseous exchange
*Hair like trichomes reduce water loss
*Shiny hair reflect excess light
*Some trichomes secrete chemicals involved in defence against pathogens/herbivores
Epidermis in the older regions of stems and roots are replaced by
Periderm after secondary growth
What are trichomes
Epidermal outgrowths such as hairs and glands
What is the main function of ground tissue
Fills the gap between dermal tissue and vascular tissue
What are the two parts of ground tissue
Cortex
Pith
What are the ovations if cortex and pith in relation to the vascular tissue
Cortex - outer to the vascular tissue
Pith - inner to the vascular tissue
The ground tissue consists of cells specialized for functions such as
Storage
Photosynthesis
Short distant transport
Support
What are the three main types of cells present in ground tissue
Parenchyma cells
Collenchyma cells
Sclerenchyma cells
What are the characteristics of parenchyma cells
Living even at functional maturity
Mature cells have primary cell walls(relatively thing and flexible), most cells lack secondary walls
Have large central vacuole
What are the functions if parenchyma cells
Perform most of the metabolic functions of the plants
Storage
Most of the parenchyma retain the ability to divide and differentiate under suitable conditions. Wound repair, tissue culture.
What are plastids
Some cells in root and stems contain plastids (leaucoplast) which store starch
What are the characteristics of collenchyma cells
Generally elongated
Thicker primary cell walls
Walls are unevenly thickened
Living even at functional maturity
Found just below the epidermis of young stems and petioles
What is the function of collenchyma cells
Give mechanical support to leaves and stems without restraining growth
What are the features if sclerenchyma cells
Have secondary cell wall produced after cell elongation
Secondary cell wall is thickened with large amount of lignin
Dead cells at maturity
What are the two types if sclerenchyma cells
Sclereids
Fibres
What are the features of sclereids
Shorter and wider than fibres
Irregular shape
Thick lignified secondary cell wall
Location of sclereids
Places where growth has stopped
Nut shells
Seed coat
Flesh of coarse fruits
Features of fibres
Usually grouped in strands
Long, slender and tapered
A use of fibres
To commercially obtain fibres
Coconut husk
Hemp fibres
Function of sclerenchyma
Provide support and strength
Xylem consists of
Vessel elements
Tracheids
Fibres
Parenchyma cells
In angiosperm and some gymnosperms
What mainly conduct water in xylem
Vessel element and tracheids
What gives mechanical strength to xykem
Fibres
What are the functions of parenchyma in xylem
Storage
Radial transportation
What types of plants contain vessel element
All angiosperm
Some gymnosperms
Features of xylem vessel element
Cylindrical and long
Wider, shorter and thinner cell walls than tracheids
Secondary walls thickened with lignin
Perforation plates are found at end walls of vessel elements. Other walls are interrupted by pits.
Water flows freely through perforated plates
Function of xylem vessel element
Provide support to prevent collapse under tension of water support
What plants have tracheids
All vascular plants
Features of tracheids
Long thin cells with tapering ends
Secondary cell wall thickened by lignin and often interrupted by pits
Water moves from end to end by pits
Thickening lignin provides support to prevent collapse under water transport
What are the components of phloem tissue
Sieve tube elements
Companion cells
Parenchyma cells
Fibres
In angiosperm
What is the dead cell in phloem
Fibres
What are the plants that lack sieve tube element and companion cells
Seedless vascular plants
Gymnosperms
What do the plants that lack sieve tube elements have instead
Long narrow cells called sieve cells
What are the organelles that are absent in sieve tube elements
Nucleus
Ribosomes
A distinct vacuole
Cytoskeletal elements
Features of sieve tube elements
Cytoplasm reduced to thin peripheral layer
Absence of nucleus, ribosomes , distinct vacuole and cytoskeletal elements
Absence of these allows passing of nutrients more freely
Chains of sieve tube elements align to form sieve tubes
The end walls of between sieve tube element contain porous plate called sieve plate
Sieve plate allows movement of fluid from one sieve element to next
What is the non conducting cell in phloem
Companion cell
Features of companion cells
Non conducting cells
Found alongside each sieve tube element and connects with it by numerous plasmodesmata
Nucleus and ribosomes of it also serves to adjacent sieve tube element
Some companion cells in leaves help with phloem loading and unloading
