ch. 35 Flashcards
cell
fundamental unit of life
tissue
group of cells working toward common functions
organ
several types of tissues that together carry out particular functions
different plant organs
roots and shoots
different organ systems of plant
root and shoot systems
purpose of roots
- anchors plant
- absorbs minerals and water
- stores carbohydrates
what is the first root to emerge?
primary root
what does the primary root branch to form
secondary and tertiary roots
what do secondary and tertiary roots do
improve anchorage and water absorption
what root system do tall plants with large shoot masses generally have
taproot system
taproot
develops from primary root and anchors plant to soil
where on the roots does absorption primarily occur?
tips of tertiary roots
small or trailing plants generally have what type of root system
fibrous root system
fibrous root system
spreads out like thick mat below soil surface
- primary root dies early on and doesn’t form taproot
adventitious roots
arise from stem and give rise to many branching lateral roots
root hairs
finger-like extensions of epidermal cells that form near the root tip and increase the absorptive surface of the root
what do most root systems form?
mycorrhizal associations
different types of specialized roots
buttress, “strangling” aerial”, pneumatophores, storage, prop
pneumo
lung or breath
phore
to bear
what does a stem consist of
- alternating system of nodes
- internodes
nodes
points at which leaves are attached
internodes
stem segments between nodes
what causes elongation of a young shoot
apical meristem of the apical bud
axillary bud
structure that has the potential to form a lateral branch, thorn, or flower
meristematic tissues within the axial buds does what?
remains dormant
- hormonally depressed from above
apical
at the tip or top
axill
arm pit
apical dominance
terminal bud released auxin, inhibiting growth of lateral buds
pruning (apical bud decapitation)
removing terminal bud allows dormant lateral buds to develop, producing bushier plants
primary function of stem
to elongate and orient shoot to maximize photosynthesis
ex. of modified stems
rhizomes, stolons, tubers
bulbs
structurally short stems with fleshy leaves or leaf bases
corms
rounded, underground storage organs consisting of a swollen stem base covered with scale leaves
leaf
main photosynthetic organ of most vascular plants
function of leaves:
- intercept light
- exchange gases
- dissipate heat
- defend plant from herbivores and pathogens
what do leaves consist of
- flattened blade
- stalk (petiole) which joins leaf to node of stem
what type of veins do monocot leaves have
parallel
what type of veins to eudicot leaves have
branching/netlike
types of specialized leaves
tendrils, spines, storage leaves, reproductive leaves,
3 tissue types that compose roots, stems, and leaves
dermal, vascular, ground
each tissue system is …
continuous throughout the plant
dermal tissue system in herbaceous plants
- consists of epidermis
- cuticle prevents water loss from epidermis
dermal tissue system in woody plants
- periderm (protective tissues) replaces epidermis in older regions of stems and roots
what surrounds stomata
guard cells - facilitate gas exchange through stomata
what does vascular tissue do
transport materials and provide mechanical support
2 vascular tissues
xylem and phloem
xylem
conducts water/dissolved minerals, travels upward from roots to shoot, consists of dead cells
phloem
transports sugars from where they are made (primarily leaves) to storage structures or sites of growth, consists of living cells
stele
vascular tissue of root or stem
stele of root in angiosperms
solid central vascular cylinder
stele of stems and leaves
divided into vascular bundles (strands of xylem and phloem)
ground tissue system
tissues that are neither dermal nor vascular
pith
ground tissue internal to the vascular tissue
cortex
ground tissue external to the vascular tissue
what does ground tissue include cells specialized for
storage, photosynthesis, support, transport
different cell types
- parenchyma
- collenchyma
- sclerenchyma
- water-conducting cells of xylem
- sugar-conducting cells of phloem
parenchyma cells
- thin/flexible primary wells
- lack secondary walls
- large central vacuole
- perform most metabolic functions
- divide/differentiate
collenchyma
- grouped in strands
- help support young parts of plant shoot
- unevenly thickened primary cell walls
- living at maturity
- flexible support without restraining growth
sclerenchyma
- rigid due to thick secondary walls containing lignin
- dead at functional maturity
- 2 types - sclereids and fibers
sclereids
- short/irregular in shape
- thick, lignified secondary walls
fibers of sclerenchyma
long and slender, arranged in threads
water-conducting cells of xylem
- 2 types: tracheids and vessel elements
- dead/lignified at maturity
tracheids
long, thin cells with tapered ends found in the xylem of all vascular plants
- water moves between tracheids through pits (thin regions lacking secondary cell wall)
vessel elements
- common to most angiosperm, few gymnosperms, seedless vascular plants
- align end to end to form long pipes (vessels)
- end walls of vessel elements have perforation plates that allow water to flow freely through the vessels
sugar-conducting cells of phloem
- alive at maturity
- lack organelles
- sieve cells
- sieve-tube elements
- sieve plates
sieve cells
seedless vascular plants and gymnosperms, sugars are transported through
sieve-tube elements
angiosperms, sugars are transported in sieve tubes
sieve plates
porous end walls between sieve-tube elements that allow fluid to flow between cells along sieve tube
what is each sieve-tube connected to a companion cell by
plasmodesmata
- nucleus/ribosomes of companion cell also serve the adjacent sieve-tube element
indeterminate growth
plant can grow through its life
- continuous growth due to activity of meristem
determinate growth
most animals and some plant organs cease to grow at certain size
apical meristem growth
- tips of roots and shoots
- primary growth
lateral meristem growth
- thickens woody plants
- secondary growth: vascular and cork cambium
vascular cambium
adds layers of secondary xylem and secondary phloem
cork cambium
replaces epidermis with periderm (bark)
primary growth of roots
- root tip covered by root cap, which protects root apical meristem as root pushes through soil
- growth occurs just behind root tip in 3 zones of cells:
1. zone of cell division
2. zone of elongation
3. zone of differentiation/maturation
primary growth of shoots
- shoot apical meristem is dome-shaped mass of dividing cells at shoot tip
- leaves of apical bud protect meristem
- axillary buds develop from meristematic cells left at bases of leaf primordial
how are axillary buds kept dormant
by chemical communication from apical bud
the closer an axillary bud is to the active apical bud…
the more inhibited it is
axillary buds are released from what if the shoot tip is removed or shaded
apical dominance
what emerges from axillary buds that have been released from dormancy
lateral shoots
what do leaves develop from
leaf primordial along sides of shoot apical meristem
what is a major avenue for loss of water
stomata
flowering plant life cycles
- annuals
- biennials
- perennials
annuals
complete life cycle in year or less
biennials
require 2 growing seasons
perennials
liver for many years
