Plant Tissue Systems Flashcards
What is a tissue?
A tissue consists of a group of one or more cell types which carry out specialized function(s)
Name the 3 main tissue systems of vascular plants
- Dermal tissue system
- Vascular Tissue system
- Ground Tissue System
Where do cells undergo changes in during differentiation?
Cytoplasm
Cell wall
Organelles
What is the dermal tissue system?
It is the outer protective covering of plants
Ex: Epidermis
Write the features of the epidermis
- Protective layer in stems and roots of the primary plant body and leaves
- Tightly packed single cell layer
- Normally covered by a cuticle which is a waxy epidermal coating in aerial parts
- Specialized cells such as guard cells, trichomes and root hairs are also found in the epidermis
- Epidermis in the older regions of stems and roots is replaced by a protective layer called periderm after secondary growth
What is the cuticle?
A waxy, epidermal coating in aerial parts of the plant
What specialized cells are found in the epidermis?
Guard cells
Root hair cells
Trichomes
What is the periderm?
A thick and tough covering formed after secondary growth, replacing the epidermis in older regions of stems and roots
What are the functions of epidermis?
- Defense against physical damage and pathogens
- Cuticle helps prevent water loss
- Root hairs involve in absorption of water and mineral ions
- Guard cells help gaseous exchange
- Hair like trichomes reduce water loss, shiny hairs reflect excess light
- Some trichomes secrete chemicals involved in defense against insects/ pathogens/herbivores
What is the function of cuticle?
Helps prevent water loss
What is the function of root hairs?
Absorption of water and mineral ions
What is the function of guard cells?
Gaseous exchange
What are trichomes?
Epidermal outgrowths such as hairs and glands
What are the functions of trichomes?
- Hair like trichomes reduce water loss
- Shiny hairs reflect excess light
- Some trichomes secrete chemicals involved in defense against insects/ pathogens/herbivores
Describe ground tissue system
- Ground tissue fills the gap between dermal tissue and vascular tissue
- They mainly consist of cortex (outside the vascular cylinder) and pith (inner to vascular cylinder)
- The ground tissue includes cells specialized for functions such as storage, support, short distance transport and photosynthesis
- There are 3 main types of cells present in the ground tissue.
- Parenchyma Cells
- Collenchyma Cells
- Sclerenchyma Cells
What are the 2 main parts of the ground tissue?
cortex (outside the vascular cylinder)
pith (inner to vascular cylinder)
What are the functions of the specialized cells in the ground tissue?
storage, support, short distance transport and photosynthesis
What are the 3 main types of cells present in ground tissue?
- Parenchyma Cells
- Collenchyma Cells
- Sclerenchyma Cells
What is the function of ground tissue system?
Ground tissue fills the gap between dermal tissue and vascular tissue
Describe parenchyma cells
- Living even at functional maturity
- Mature cells have relatively thin and flexible primary cell walls, and most cells lack secondary cell walls
- They have a large central vacuole
Describe the cell wall of parenchyma cells
- Mature cells have relatively thin and flexible primary cell walls
- Most cells lack secondary cell walls
What are the functions of parenchyma cells?
- Performs most metabolic functions of plants (ex: synthesis of various organic products)
- Storage (some cells in root and stem contain plastids (leucoplasts) which can store starch)
- Most parenchyma cells retain the ability to divide and differentiate under suitable conditions. This ability is important in wound repair
- These abilities also make it possible to multiply and differentiate cells even from a single parenchyma cell in tissue culture practices
What ability of parenchyma cells is important for wound repair
- Most parenchyma cells retain the ability to divide and differentiate under suitable conditions. This ability is important in wound repair
Write the functions of leucoplasts of parenchyma cells
Storing starch
What is a metabolic function performed by parenchyma cells?
Synthesis of various organic products
Describe collenchyma cells
- They are generally elongated
- They have thicker primary cell walls than parenchyma cells
- Their walls are unevenly thickened
- Young stems and petioles often have strands of collenchyma just below the epidermis
- Even at functional maturity, they are living, flexible, elongating, with stems and leaves they support
Describe the cell walls of collenchyma cells
- They have thicker primary cell walls than parenchyma cells
- Their walls are unevenly thickened
Where are collenchyma cells found?
Young stems and petioles often have strands of collenchyma just below the epidermis