Lab 1 Flashcards
differentiation
process in which cells become specialized in structure and function
tissue
an aggregate of cells usually of a particular kind together with their intercellular substance that form one of the structural materials of an organism
meristem
a region of plant tissue consisting of actively dividing cells forming new tissue
primary meristem
meristem that produces the tissues of the primary plant structure
RAM and SAM
indeterminate growth meristem
produces parts of the plant that can grow for variable periods of time, and vary in size and shape dependent on the local environment
determinate growth meristem
usually produces part of the plant that has a predictable size and form, such as the flower
stem cell/initial cell
undifferentiated cell present in the meristematic tissues
cell from which all other cells with specialized functions are generated
histogen
zone of primary tissue from which the specific parts of a plant organ are believed to be produced
plerome, periblem, dermatogen and calyptrogen (not always)
procambium
primary tissue of roots and shoots that forms the vascular tissue
primary structure
first structure of the plant consisting of primary tissues
root
an organ in vascular plants that anchors the plant and enables it to absorb water and minerals from the soil
first organ to develop in germinating seed
root cap
a structure that covers the tip of a root, protecting the root from injury
it covers meristematic cells within the root tip
columella
central part of root cap, it is made up of cells arranged in files
the cells contain multiple amyloplasts (statoliths) with starch
the cells contribute to gravitropism by the movement of statolith to in cells
root border cells
cells that separate from the root tip of higher plants and disperse individually in the soil solution (or water)
their functions are: protection from phatogens, modification of chemical and physical soil properties, regulation of symbioses
statoliths
specialized plastids (amyloplasts) containing dense starch grains, that let plants know up from down = they take part in gravitropism
radicle
an embryonic root of a plant
it is the first organ to develop during germination
it grows downward into the soil, anchoring the seedling
adventitious root
roots that rise form the point other than radicle or root axis of the plant e.g. from stems or leaves; examples are aerial roots and prop roots above ground
seminal root
one of the first structures to emerge from a germinating seed
seminal roots make up the root with fibrous root system, where radicle is retarded
lateral root
a secondary plant root that extends horizontally from another root in secondary meristems, when the cell cycle and mitosis start in cells of pericycle
fibrous root system
monocots and ferns
fibrous root system forms a dense network of roots that is closer to the soil surface
the roots making it up are called seminal roots and they branch out
the radicle is retarded or it does not grow
tap root system
dicots
they are made up of a central large root, which develops from the radicle and it is called a taproot
from the taproot, lateral roots develop
root hair zone
primary root structure
small and thin extensions of the root
it is important for water and nutrients uptake bc it has the largest surface thanks to the root hairs
rhizodermis/epiblem
primary surface layer of the root, similar to epidermis but of different origin and function
the cells adhere strongly to each other, they have thin, primary cell walls, large central vacuole
includes root hairs
very little cuticle
root hair
outgrowths of a root’s epidermal cells that allow for greater surface area for absorption of nutrients and water
also pathogen protection
adherence to the soil
participation in rhizosphere formation
trichoblast
specialized cells from which the root hairs of epidermal cells have originated
primary cortex
made up of endodermis, primary cortex parenchyma and epidermis
transport and store nutrients and provide support
stele
pericycle and strands of vascular tissue - composed of vascular bundles , which are formed from primary xylem and primary phloem
pericycle is inactive procambium
rhizosphere
the narrow region of soil or substrate that is directly influenced by root secretions and associated soil microorganisms known as the root microbiome
exodermis
cell layers just under the epidermis to prevent water loss
exodermis represents an unicellular cell layer located at the outer surface of the root directly below the root epidermis
parenchyma
fundamental tissue composed of thin-walled living cells, there are different types ground parenchyma, hydrenchyma, chlorenchyma, storage parenchyma, aerenchyma
endodermis
the innermost layer of the cortex in plant roots; a cylinder one cell thick that forms the boundary between the cortex and the vascular cylinder
casparian strips
suberin lamellae
could be secondary wall thickenings
it consist also of passage cells that stay in the second stage of development and provide pathways for transport of water and nutrients and entrance of mycorrhizal fungi
symplast
the continuum of cytoplasm connected by plasmodesmata between cells
transport across plasmalemma and cytoplasm through plasmodesmata
apoplast
the continuum of cell walls plus the extracellular spaces
transport through unmodified, cellulose cell walls and intercellular spaces
Casparian strip
hydrophobic cell wall impregnations; they form a barrier forcing ions to pass through the selectively permeable plasma membrane into the cytoplasm rather than move along the cell wall
control of water and solute transport
forces symplast
pericycle
the outermost layer of the vascular cylinder of a root, where lateral roots originate
mitoticaly inactive procambium
site for the initiation of lateral roots as the secondary meristem
vascular bundle
plant stem structure that contains xylem and phloem tissue
it can be found in the stele
phloem
the vascular tissue in plants that conducts sugars and other metabolic products downward from the leaves
most of the phloem is alive
primary phloem
vascular tissues originating from apical meristem growth it is present in primary structures it is important for transport of nutrients
protophloem
the part of the primary phloem that differentiates early, while adjacent cells are still elongating
metaphloem
the part of the primary phloem that differentiates late, after adjacent cells have completed their elongation
xylem
vascular tissue that carries water upward from the roots to every part of a plant
most cells are dead
primary xylem
formed at root and shoot apex early in development, they form vascular bundles in leaves and young stems
protoxylem
the part of the primary xylem that differentiates early, while adjacent cells are still elongating
metaxylem
the part of the primary xylem that differentiates late, after adjacent cells have completed their elongation
