Practical #2 - Plant Form and Function Flashcards
What are the 3 basic types of cells in nonmeristematic tissues?
- Parenchyma
- Collenchyma
- Sclerenchyma
What are the attributes of a parenchyma cell?
- forms much of the ground tissue
- mesophyll of leaves, cortex and pith of stems
- Living when functionally mature
- Aid in metabolism, and storage.
- Most epidermis and edible parts of fruits are parenchyma cells
- Thin and flexible primary walls
- made of cellulose
- Developing plants use these before specializing further
What are the attributes of a Collenchyma Cell?
- Provide support for young stems
- Support vascular tissues, leaf veins, petioles
- Alive at functional maturity
-
Thicker primary walls than parenchyma cells
- composed of cellulose and pectin
- Unevenly thickened
- Think of strings in the stalks of celery
What are the attribute of sclerenchyma cells?
-
thick secondary walls
- for support in non growing regions of the plant
- made of cellulose and ligning
- Cannot elongate
- dead at functional maturity
- Examples
- vessel elements, tracheids
- fibers and sclereids
What is a meristemic cell and what are the 3 types?
- A cell that retains the capacity to undergo cell division
- apical meristem
- primary meristem
- lateral meristem
What is an apical meristem?
- locaed on the tips of young shoots and roots
- Increase the length
- these produce the primary meristem and lateral meristems!
What are Primary Meristems?
- consist of three kinds which are produced by teh apical meristem
- Primary meristem is responsible for primary growth (Increase in the length of stems and roots)
- 3 types:
- protoderm
- Procambium
- Ground Meristem
What are the functions of the Protoderm, Procambium, Ground Meristem?
-
Protoderm
- produces the otuer epidermis to stems and roots
-
Procambium
- produces the vascular tissues in stems and roots
-
Ground Meristem
- produces the ground tissues in stems and roots
What is the lateral Meristem?
- Increases the girth of indvidual stems and roots, but not leaves
- responsible for secondary growth
- 2 major types
- Vascular cambium
- Cork Cambium
What is the Vascular Cambium?
- prodcues tissues that increase the girth of the plant
- particularly - secondary xylem and secondary phloem
-
layer and layers of secondary xylem form wood over time
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-
layer and layers of secondary xylem form wood over time
- particularly - secondary xylem and secondary phloem
What is the Cork Cambium?
- Acts to produce a thick covering for large stems and roots
- Parenchyma cells in the cortex become he cork cambium
- Produces Cork Cells and Secondary cortex cells
-
Cork Cells
- have a waxy coating that acts as a barrier
- Along with cork cambium form the periderm
- Cortex Cells
-
Cork Cells
What produces bark?
- Scondary Phloem cells and the Periderm
- Bark replaces the epidermis over time
What are the 3 types of nonmeristematic Tissues?
- Dermal Tissues
- Vascular Tissues
- Ground Tissues
What do Dermal tissues consist of?
-
Epidermis
- acts as the outer skin of the plant
- Epidermis produces a wazy substance, cutin, that forms the cuticle.
What are the functions of Vascular Tissues? What are the types of Vascular Tissues
- Involved in the transport of materials through the plant, upward from roots to stems and leaves and downward from leaves to roots
- 2 types:
- Xylem - carries xylem sap from roots to active tissues of stems and leaves
- Phloem - carries phloem sap from one part of the plant to another
What are the 4 external features of a Stem?
- Node - portion of the steam from which leaves and buds and branches arise
- meristematic tissues are located here
- Internode - portion of the stem that lies between two nodes
- Lenticels - raised circular slit-like structures on the bark of young woody twigs that funtion in gas exchange
- Buds - undeveloped shoots
- Covered by bud scales
- Terminal Buds (Apical buds)
- Axillary buds (Lateral buds)
Epidermis of the stem structure
- Single layer of parenchyma cells, derived from the protoderm
- Outer wall covered with waxy substance - cutin, which forms the cuticle
-
Guard Cells surround the stomata…but these are most abundant on leaves
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Stem Cortex structure
- multilayered, complex tissue
- Originates from the ground meristem
- consists mainly of collenchyma and parenchyma cells
Stem Vascular tissue structure
- Primary Xylem, Primary Phloem, Vascular Cambium
- Vascular tissues arise from the procambium
- Normally condensed into bundles
- Vascular cambium is found between the xylem and phloem (fascicular cambium)
Pith, Stem Structure
- Located in the center of the stem and is composed of parenchyma cells, originating from the ground meristem
- Sometimes they break down leaving the center hollow
What are the differences in primary tissues origins between Monocots and Eudicots
- In monocots the vascular bundles are scattered thoughout the ground tissue of monocot stems.
- Cortex and pith are indistinguishable, so all tissue derived from the ground meristem are called ground tissue
Phloem Transport Structures
-
Sieve-Tube Members
- Cells that make up the phloem tube.
- Arranged end to end
- Contain porous end walls sieve plates
- alive at functional maturity
- no nuclei and ribosomes
-
Companion Cells
- adjacent to and connected to sieve-tube members.
- Retain nuclues and alive at maturity
- Assist sieve-tube members in metabolism and function