Lecture 3: Body basics; Ground tissue Flashcards
What does the epidermis control?
- water loss
- gas exchange
- leaf temperature
- invading organisms
- compound exchange
What are the 4 components of the epidermis
cuticle
epidermal cells
stomata and subsidiary cells
trichomes
What are the 3 ground tissues called?
parenchyma
collenchyma
sclerenchyma
What is the function of parenchyma
photosynthesis
storage
secretion
respiration
What is the function of collenchyma
support young growing organs
What is the function of sclerenchyma
strengthen and support plant parts no longer elongating
What are the characteristics of parenchyma?
- most common cell type found in all organs
- thin walled
- vacuolated
- living cells (up to maturity)
- polyhedral shape
- elongated or branched
true or false; parenchyma cells are very specialized eg. companion cells and albuminous cells in vasculature
true
What are companion cells and albuminous cells active in?
phloem exchange
true or false; parenchyma has air spaces? Why?
true; aquatic plants uses it for floatation eg. water lily or roots that are water logged
How does the intercellular space arise between parenchyma cells?
by splitting or rupturing
- by splitting middle lamella
- or rupturing of cell
true or false; the parenchyma cells dictate the apple crispiness
true
What are the parenchyma cell inclusions
- chlorenchyma (chloroplasts); leaves, stems
- tannins (cell vacuole); grapes
- protein & lipid bodies; soybeans
- red anthocyanin pigments in vacuole (strawberry)
- aerenchyma
- mucilage and/ or crystals in idioblasts
- wall ingrowth in TRANSFER CELL for transport
What are the two types of parenchyma
palisade parenchyma
spongy parenchyma
true or false; parenchyma retain the ability to divide at maturity
true
- important for regeneration after wounding
- adventitious rooting of cuttings
Describe collenchyma
- shape of cell
- thickness
- where is it found
- what is contained in its walls
- elongated living cells
- unevenly thickened primary cell walls
- found in stems; leaves; flowers; fruits; roots
- usually beneath epidermis in discrete strands (eg. celery) or continuous layers
- walls contain alternating layers of pectin + cellulose
Describe sclerenchyma
- dead cells with lignified secondary cell walls
- mature cells cannot elongate
- provides structural support
What are the two types of sclerenchyma
fibre
sclereids
Describe fibres
- shape
- magnitude of strength
- purpose of lignin
- do monocots have the strongest fibers
- what is organized into
- long, narrow cells with pointed tips eg. hemp cells up to 5.5 cm long
- extremely strong
- depends on lignin content
- monocots have the hardest fibres
- usually in bundles or a cylinder especially near xylem
What are the commercial uses of fibers
textile fibers (soft): cotton, hemp
Cordage fibers: agave (sisal), NZ flax
brush fibers (hard): palm, sorghun
paper: hemp, papyrus, mulberry, pine
What is the quality of paper determined by?
fiber size
lignin content
cellulose orientation
What does lignin reinforce
strength
What does cellulose provide
hydrophilicity, bonding
What does fibre length provide?
intertwining
What is Hemp - Cannabis sativa?
textile fibre that doesn’t secrete THC
What can Hemp provide?
- clothing
- paper
- building materials
- fuel
- cosmetics
- beverage
- food
- cleaners
- paint products
What can be harvested from Hemp
seed
seed oil
fibers
seed meal
true or false; does hemp makes you high?
false; but it can give you a headache
What do you call coconut fibers
coir
What are sclereids
- extremely variable in shape
- hard cell walls
- often pitted
eg. gritty texture of pears and feijoa
walnut seed coat - occurs singly or in aggregates throughout ground tissue
what type of cell do we mainly eat?
parenchyma
What kind of cells are mostly in capsicum
parenchyma; chlorenchyma
What kind of cells are mostly in pumpkin
parenchyma; filled with carotene pigments
What are bean cells filled of?
parenchyma cells filled with starch
true or false; parenchyma cells initiate adventitious roots on stem cuttings
true
definition of totipotent
capable of giving rise to any cell type
true or false; parenchyma cells are totipotent
true