CH. 34 & friends Flashcards
Most angiosperms belong to one of two major clades:
Monocots & Eudicots. These two clades account for 97% of flowering plant species.
Monocots
Generally narrow leaved flowering plants (like grasses, lilies, and orchids) Have one Cotyledon (v.s. 2) Vascular bundles in the stem that are scattered. (v.s. in circles) Major leaf veins are parallel have fibrous root system (vs taproot) have flowers which contain parts that occur in 3’s (v.s. 4 or 5) pollen grains contain 1 furrow or pore (v.s. 3)
Eudicots
broad leaved flowering plants (like soybeans, roses,sunflowers, and maples.) Have two Cotyledon (v.s.1) Vascular bundles in the stem are arranged in concentric circles (v.s. being scattered) Major leaf veins are reticulate (meaning they form a network.) Have taproot system (v.s. fibrous) have floral (instead of flowers) which contain parts that occur in 4’s & 5’s (v.s.3) pollen grains contain 3 furrows or pores (v.s. 1)
Cotyledon
“A leaf in the embryo” A cotyledon is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon usually becomes the embryonic first leaves of a seedling
Tissue
organized group of cells that work together as a structural and functional unit
plant systems are classified in three tissue systems
dermal, ground and vascular
dermal tissue system
Forms the epidermis (outer covering) and usually consists of a single cell layer known as the epidermis (outer covering).
(Leaves typically have two layers of epidermis).
Found above and below ground
The dermal system is a concept, the protective layer on the outside of the plant. All plants start with an epidermis, but as a plant becomes woody the epidermis is shed and replaced by a tougher layer (bark).
cells of epidermis
small and round initially. usually have a small central vacuole or none at all.
Once cell division ceases in the epidermis of an organ, the epidermal cells expand.
The cells above the ground (called trichomes) secrete a protective extracellular layer called a cuticle as well as other functions
Some epidermal cells differentiate to form one of three specialized structures:
- Stomatal guard cells (form pores for gas exchange in leafs)
- Trichomes (provide protection against insects and damaging solar radiation)
- root hairs (increase root surface area greatly providing a larger uptake in water and minerals)
cuticle
limits water loss, reflects potentially dangerous solar radiation, and serves as a barrier against pathogens
Ground tissue system
virtually all of the tissue lying between the dermal tissue and the vascular tissue.
Makes up most of the plant body.
functions primarily in storage, Mechanical support, photosynthesis and other special metabolic activities (e.g. for defense). Also helps New growth and repairing damage.
If the stem is damaged, the ground tissue will start dividing and repair the damage.
The ground tissue has two major regions in eudicots;
pith and cortex
3 cell types found in ground tissue
parenchyma cells, collenchyma cells, and sclerenchyma cells. They are classified according to their cell wall structure.
parenchyma cells
most common cell type in plants. large vacuoles, thin cell wall. only a primary cell wall. play an important role in photosynthesis retain the capacity to divide and give rise to new cells
collenchyma cells
similar to parenchyma cells but modified for flexible support. (lets stems blow in wind without snapping) primary cell wall is thick in corners. no secondary wall provide support to nonwoody stems, growing organs, and leaf petioles.
sclerenchyma cells
thick secondary cell walls that enable these cells to preform their primary function: support Many cells undergo programmed cell death and preform their supporting function while dead.
2 types of sclerenchyma cells
elongated fibers and variously shaped sclerids. (pg714)
Vascular tissue system
The plants plumbing/transporting system. Its the distinguishing system in vascular plants.
•transport of water, minerals, carbohydrates, and other substances
The Vascular tissue systems two constituent types of tissue
Xylem and Phloem
Xylem
distributes water and mineral ions taken up by the roots to all the cells of the stems and leafs
Xylem in Angiosperms Contains Two Types of Water-Conducting Cells called Tracheary Elements (Tracheary elements: a collective term that encompasses both tracheids and vessels)
phloem (function)
preforms a variety of functions including; transport, support, and storage.
Phloem conducts sugar, amino acids, certain minerals, hormones, and other substances throughout the plant body
Sieve tube elements
Sieve tube elements are long, thin cells with cytoplasmic channels (sieve pores) in their end plates (sieve plates).
In flowering plants the charateristic cells of the phloem are sieve tube elements.
like vessels these cells meet end to end and form long tubes that transport carbohydrates & many otheerr materials from their sorces to consume/ store them.
Cell walls contain plasmodesmata which enlarges pores.
the end walls look and act like sieves and are thus called sieve plates.
Most organelles are missing from the sieve tubes because they would be in the way of the sugar transport but they are still living cells.
The sieve tubes are metabolically active and they cannot afford to have a thick secondary cell wall.
companion cells
specialized parenchyma cells that contain all the organelles normally found in a plant cell; they are not conducting cells but provide materials to maintain the protoplast of sieve-tube elements
They function as a “life support system” for sieve tube elements.
companion cells do transcription and translation for the sieve cell, and they have a single nucleus
Vessel elements
in flowering plants individual cells that make up vessels which compose an “open pipeline” for water cunducting. theyre laied out end to end. short and wide
tracheids
evolutionarily more aincent then vessel elements .
when they die their internal composition disintegrate and pits remain between the cells allowing water and minerals to move between cells (and thus thru xylem tissue)
Tisue location in the roots
tissue location in leafs
Tissue location in stems
Unicelllular trichomes:
act as physical barrier and entrapment devices
Glandular trichomes:
secrete anti-herbivory compounds. columns full of nasty things for insects. These cells have very thin walls and burst open when an insect encounters it, giving the insect a mouthful of nasty substances.
stomata
a pore that serves as passageways between the enviroment and the leafs interior.
When open CO2 can enter enter photosynthetically active tissues, O2 can leave, but water is also lost in the process.
Stomata consist of two guard cells, which change shape to open or close an opening called a stomatal pore
Leaf
Photosynthesis
Special modifications: storage (e.g. base of onion leaves); support (e.g in pea tendrils)
