Unit 4- Plant Tissues Flashcards
What is division of labour?
Specialization of cells to carry out a specific function
- tissues are structurally adapted to perform a specific function
What is an organ?
Many tissues grouped together to form a structure with a specific function
What is an organ system?
Groups of organs with closely related structures working together to perform a specific function
What is meristematic tissue?
- Actively dividing cells forming new cells through mitosis
- Cells are not yet differentiated/ specialized to perform a specific function
- Found in growth regions of plant: root, stem + shoot
What is permanent tissue?
- Derived from meristematic tissue
2. Result of cell enlargement + cell differentiation ( has a specific function)
What is simple tissue?
- Cells of the same type
- Perform the same function
- parenchyma, sclerenchyma, collenchyma
What is complex tissue?
- Cells of different types
- Perform more than one function
- epidermal tissue, vascular tissue
What is the structure of apical meristems?
- Small + cubic
- Thin- walled
- Large, prominent nucleus
- Dense cytoplasm
- No vacuoles
- No intercellular spaces
What is the function of apical meristems?
Primary growth
- increase in stem and root length
Where are apical meristems found?
Tips of roots and shoots
Where are lateral meristems found?
- Sides of roots ad stems
2. Cambium- found between xylem and phloem in vascular bundles
What is the structure of lateral meristems?
- Long and flattened
- Thin-walled
- Large, prominent nucleus
- Dense cytoplasm
- Numerous small vacuoles
- No intercellular spaces
What is the function of lateral meristems?
- Secondary growth- increase in width of plant
- Vascular cambium- produce xylem + phloem
- increase diameter of stems
and roots in perennials - Cork cambium- thick layer of bark in stems
Where is epidermal tissue found?
• covers the surface of a plant organ
Structure of the epidermal cell?
- Thick outer wall
- Only 1 cell layer thick
- Tightly packed together
- May be modified
- stomata of leaves
- root hairs of roots
What are the functions of epidermal tissue?
- Protection of plant organs from desiccation & physical damage
- Produces cuticle layer- prevents plant from losing water through transpiration
- Single, transparent layer without chloroplasts
- allows light to penetrate mesophyll tissue
What is stomata?
- Tiny opening on a leaf
- Formed by guard cells ( modified epidermal cells)
- Found mainly in lower epidermis of leaves
Structure of stomata?
- Unevenly thickened walls
- inner (ventral) thicker than outer (dorsal) wall - Chloroplasts - not transparent
- Stoma- pairs of bean shaped cells
- Stomata like pore
Function of stomata?
- Regulates/ controls gaseous exchange + transpiration by opening and closing of he stomata like core
Where are root hairs found?
Roots
Structure of root hairs?
Unicellular outgrowths
Function of root hairs?
Outgrowths- increase surface area for water absorption
Where is parenchyma tissue found?
- In all plant organs
- pith + cortex of stem
- roots
- mesophyll of leaves - Forms bulk of leaves
What is parenchyma tissue?
- Simplest type of living tissue
- Living cells
- Basic tissue of plants
- Can be elongated in one plane
- e.g. Palisade cells in leaf
• aerenchyma- parenchyma tissue of plants growing in waterlogged soils
• chlorenchyma- parenchyma cells with chloroplasts
What is the structure of parenchyma tissue?
- Large vacuoles when mature
- Thin permeable cellulose walls
- lateral movement of water and minerals - Large intercellular airspace = loosely packed
- allow for gases (CO2 & O2) to circulate - Isodiametric
- sponge cells
Function of parenchyma tissue?
- Packing tissue- fills spaces between other tissues
- Storage tissue- stores water/ sugar/ starch in roots, stems or leaves
- Intercellular air spaces store gases for photosynthesis + respiration
- spaces allow water to pass through