Early development and Plant Tissues Flashcards
Embryogenesis
Formation of the embryo
-first two stages of seed development
-stable she’s plant body plant
Areas of the plant embryo is in what patterns
Apical-basal pattern
-chalazel end->embryo
-micropilar end->suspensor
Radical pattern-concentrically arranged tissue
What two areas is the embryo divided into
Embryo proper with Protoderm
Suspensor (attach embryo to mother)
Micropyler
Only opening to seed
Pericarp
Mature ovary wall of grasses
Monocot and dicot number of cotyledons
1 and 2
Procambium is the Origin of what tissue
Vascular
Endosperm role in seed
Consumed for starch
Nutrients transferred to cotyledons to be early storage organs
Stages of embryo
2 cell stage
6 cell proembryo
Globular stage (proceeds cotyledon development)
Heart stage (in eudicots)
Torpedo stage
Mature embryo
Maturation phase
Massive build up of food reserves
-starch
-storage proteins
-oils
Desiccation
Loss of 90% or more water content
-hardening of seed coat
-metabolism decreases
-dormant or quiescent
Germination and processes of it
Resumption of growth of the embryo requiring:
-water
-oxygen
-temperature
-imbibing of water
-activation of enzymes already present in seed
-glucose breakdown (anaerobic early, aerobic when seed coat is ruptured)
When seeds germinate in which ways can they do so?
Epigeous- cotyledons above ground, hypocotyl elongates
Hypogeous-cotyledons underground, hypocotyl does not elongate
The seed contains what
Embryo, stored food, seed coat
Before the embryo proper and suspensor have been established, what is the developing embryo referred to as?
Proembryo
Apical meristems
Tips of roots and shorts that consist of cells that are capable of repeated division.
Involved in elongation of plant
The suspensor is short lived and undergoes programmed cell death at the same time as which stage of development
Torpedo
Therefore not present in the mature seed
Plumule
The first bud of an embryo; the portion of the young shoot above the cotyledons
Epicotyl
Hypocotyl
Radical
The upper portion of the axis of an embryo or seedling, above the point of insertion of the cotyledons (seed leaves) and below the next leaf or leaves.
The portion of an embryo or seedling situated between the point of attachment of the cotyledons and the radicle.
The embryonic root
Hilum
Scar left on the seed coat after the seed has separated from its stalk or funiculus.
Commonly associated with the micropyle
During early germination, glucose breakdown may be entirely _____ but as soon as the seed coat is ruptured, the seed switches to an _____ pathway
Anaerobic
Aerobic
Minimum, maximum and optimum germination temperatures
Min: 0-5°c
Max: 45-49°c
Optimum: 25-30°c
Plant hormones for germination and dormancy
Abscisic acid promotes dormancy
Gibberellic acid promoted germination
Apical meristems and derivatives purpose
Growth, morphogenesis and differentiation
Growth:irreversible increase in size including cell division and cell enlargement
Morphogenesis: assuming a particular shape expansion followed by cell division
Differentiation: cells with identical genetic information become different from one another and the meristematic cells that generated them
Apical meristem differentiation pathways
Apical meristems produce:
Primary meristems:
-Protoderm
-ground meristems
-Procambium
Which produce primary tissues systems:
-dermal
-ground
-vascular
Basic types of plant cells
Parenchyma
Collenchyma
Sclerenchyma
Meristems
Groups of undifferentiated cells that divide and produce more undifferentiated cells
-initials
-derivatives (first step of differentiation)
Parenchyma
-most common type of plant cell
-general function is filling
-alive at maturity
-least specialized
-thing cell walls
-no secondary cell wall
-inexpensive
-chlorenchyma
-storage of food and water
Found in stems, leaves, seeds, fruits
Collenchyma
-flexible support cells with resistance to wind
-elongated, various shapes
-alive at maturity
-turgid -> support
-no secondary cell wall
-primary cell wall unevenly thickened
-found beneath epidermis in stems and petioles, and bordering veins in eudicots
Sclerenchyma
-rigid support
-secondary cell wall lignified
-dead at maturity
-expensive
-has fibers and sclereids
Sclerenchyma fibers and sclereids
Fibers:
-elongated
-thick secondary cell wall
-flexible, strong in groups
-storage and support
-associated with xylem and phloem
Sclereids:
-various shapes
-hardness-seeds “stones”
-protective function
-found throughout plant
Tissue systems and their main parts of plants
Dermal:
-epidermis
-periderm
Ground:
-parenchyma
-collenchyma
-sclerenchyma
Vascular:
-xylem
-phloem
Epidermis
Outer protective layer
-one cell thick
-most cells are relatively unspecialized
-cuticle of Cutin and waxes to prevent water loss
-aeration with stomata
-contains guard cells, trichomes and other specialized cells
Leaf epidermis is involved in ______ which in involved in circadian leaf movement and photo periodic induction of flowering
Light perception
Specialized dermal cells
-guard cells
-trichomes
-root hairs
Epidermis of a eudicot and monocot
Eudicot-stomata randomly placed in epidermis
Monocot-stomata in brick like fashion
Leaf epidermis is ______ to let light in
Translucent
Trichomes
Plant hairs
Functions:
-absorption: root hairs
-temperature regulation
-reflective
-reduce rate of water loss by creating a boundary layer to reduce gradient
-defensive: sharp, rigid
Trichomes can be the main area of ______ production
Secondary metabolites
Cotton puffs are examples of
Trichomes
Xylem
-hollow dead cells
-thick lignified cell walls
-primary from Procambium
-secondary from vascular cambium
-includes tracheids and vessels
Function: transport of water and mineral nutrients from roots. And support
Wood is formed from the accumulation of
Secondary xylem
Tracheids
-tapered ends that overlap
-pits (interruption of secondary wall)
-dead when functional
-lack perforations
Part of xylem
Chief water-conducting element of gymnosperms and seedless vascular plants; and some angiosperms
Vessels
Part of xylem
-much wider
-perforated plates
-dead when functional
-more efficient water conducting
Chief water-conducting element in angiosperms and gnetales
Periderm
Replaces epidermis as protective tissue in roots and stems; aeration of internal tissue via lenticels. In secondary growth
Cork cells, cork cambium, parenchyma-like cells
Sieve cell
Part of phloem
-food-conducting element in gymnosperms!!!!
-elongated and tapering shape
-alive at maturity
-no nucleus at maturity
-sieve areas (pores)
Albuminous cell
Part of phloem; specialized parenchyma believed to play a role in the delivery of substances to the sieve cell; including information molecules and ATP.
-elongated shape
-alive at maturity
-gymnosperms
-has lots of Plasmodesmata
Similar to
Companion cells of angiosperms
Sieve-tube element/ members
Part of phloem
-food-conducting element in angiosperms!!!!
-elongated shapes
-alive at maturity
Companion cell
Part of phloem; believed to play a role in the delivery of substances to the sieve tube element including information molecules and ATP
-alive at maturity
-specialized parenchyma cell
Simple and complex tissues with examples
Tissues composed of only one type of cell-parenchyma, collenchyma, sclerenchyma
Tissues composed of more then one type of cell-xylem, phloem, epidermis and periderm
Xylem derives from the ________
During secondary growth, the xylem is derived from the ______
Procambium
Vascular cambium
What substances are transported in phloem
-sugars
-amino acids
-lipids
-micronutrients
-hormones
-floral stimulus
-proteins
-RNA
Xylem characteristics
-hollow, dead cells
-thick, lignified cell walls
-primary from Procambium, secondary from vascular cambium
-tracheids and or vessels
Wood is made up of
Secondary xylem
Phloem characteristics
-transport of photosynthates: amino acids, sucrose, hormones
-located on outside of stems and roots
-made of fibers and parenchyma
Sieve plate
Larger openings in sieve tube meme era of angiosperms
Callose plugs
Stain dark and appear on injury of plant.
Similar function to torus
Torus
Membrane of bordered pits that blocks substances from moving to the next tracheid.
-prevent embolism: bubble of air in vessel
P protein
Stains with Callose upon injury
-not known function although appears to be related to wounding around amino acids
Ground tissue
Or fundamental tissue
-parenchyma
-Schlerenchyma
-collenchyma
Found in cortex or pith
Photosynthesis and storage function
Dermal tissue
-epidermis: outer protective layer, one cell thick
-fatty Cutin layer in cuticle
-each layer sometimes
