chapter 30 Flashcards
1 modular unit is composed of?
internode and node
stems grow by adding new cells at tips…
shoot apical meristem
shoot apical meristem
group of totipotent cells that gives rise to new tissue
totipotent cell
immature cells that can give rise to any type of mature cell
site of rapid cell division
shoot apical meristem
Most of the increase in cell size
occurs after _____ cell division
is complete
mitotic
within elongating internodes, cells increase many times in length, and the ____ comes to occupy over ___ of the interior volume of the cell
vacuole, 90%
shoots are made by
the repeated productions of nodes and internodes
meristem identity gene
a gene that contributes to meristem stability and function
evolution of leaves (3)
- formation of flattened organs
- meristem identity gene down-regulated and leaf identity genes up regulate
- evolution of new meristem enabling leaves to explain into flattened photosynthetic structures that capture sunlight
a structure that connects a leaf to its stem
petiole
primordia
leaves begin as a bump which forms on the inside of the shoot apical meristem
3 types of leave structures
- alternate
- opposite
- whorled
bud scales
hard leaves that protect shoot apical meristem from water loss and damage due to winter cold
provide protection
climb
attract pollinators
primordium
singular
a plant cell that retains the capacity for cell division and gives rise to xylem and phloem
procambial cell
where are sepals, petals, stamens, carpels developed
primordia
what triggers the conversion of meristem to floral meristem?
protein florigen
floral meristems differetiate
- lose capacity for continued indeterminate growth
- floral organs develop from primordia, occurring in whorls
a chemical signal that influences physiology and development in both plans and animals
hormones
____ determine how leaves are arranged, where branches form, and how much internodes elongate
_____ which axillary buds grow into branches and guide the growth of a stem toward sunlight
hormones
hormones affect plant growth and development both by influencing ________ processes, such as the activity of membrane ____________, and by altering patterns of __________.
physiological, transport protein, gene expression
what are the 5 major hormones
- auxin
- gibberellin acid
- cytokinins
- ethylene
- abscisic acid
which hormones are for growth
- auxin
- givverellin acid
- cytokinins
which hormones are for senescence
- ethylene
- abscisic acid
which hormones have a single active form (3)
- auxin
- aba
- ethylene
which hormones have variety active forms (2)
- gibberelicc
- cytokinins
what does an auxin do? (3)
- it causes shoot to elongate
- determines where new leaves will form
- connects new leaves to xylem and phloem
synthesis and transport (auxin) 2
- synthesized primarily in shoot apical meristems and young leaves
- transported by polar transport through phloem
high levels of auxin trigger formation of new leaf ____
primordia
why does auxin accumulate in leaf primordia
because it promotes cell expansion so that the young leaves grow
why does auxin go down through the leaves
it causes cells to elongate and to produce more auxin transport proteins
The coordinated movement of auxin across many cells in a single direction is referred to as
polar transport
in the cell walls, cells are ____
uncharged auxins
in the cytoplasm cells are ____
negatively charged
PIN proteins
located only on the Basel side of each cell
where can auxin exit
only through the Basel end of cell aka PIN protein
gibberellin acid
- control internode elongation by reducing force needed for plan cell walls to explain
synthesis and transport of gibberellin acid
synthesized in the growing regions of both roots and shoots
cytokinins
- produced in plant meristems
- stimulates growth of branches from axillary buds
synthesis and transport of cytokinins
transported in both xylem and phloem
and synthesized in both root and shoot meristem
apical dominance
the suppression of growth of axillary buds by the shoot apical meristem, typically because of auxin and cytokinins
what do apical dominance do?
prevents branches from being formed too close to the shoot tip, yet new branches can still be formed if the shoot meristem is damaged
strigolactone
a plant hormone that inhibits the outgrowth of axillary buds
plants with strong apical dominance _______ and plants with weak apical dominance _________
- will have a main stem. with a few side branches
- will have many branches
ethylene
- reduces cell elongation
- triggers fruit ripening
- stimulates formation of air spaces in roots
Where is ethylene transported
can be transported in xylem
ABA aka abscisic acid
transported from roots to leaves in xylem
maintains seed dormancy
what does ABA trigger?
stomata closure
secondary growth
- shoot apical meristems and axillary buds enable plants to grow in length and to branch
floral meristem enables development of?
flowers
why do plants need to grow in diameter?
- strengthen the stem
- increase capacity of vascular system
the source of a new cell that allows plants to grow in diameter
lateral meristems
when do lateral meristems form?
when elongation is complete
plants produce ____ distinct lateral meristems that together result in ______ growth.
2, secondary
source of new xylem and phloem is called?
vascular cambium
plants with a secondary growth are usually?
woody
located on the outside of the vascular cambium, protects it from herbivores, mechanical damage, desiccation and sometime fire.
cork cambium
where are vascular cadmium derived?
form procambial cells within vascular bundle and parenchymal cells, both cells become meristamtic
what makes up the bark
all material produced to the outside of the vascular cambium, including secondary phloem
what is sapwood
transports water from roots to shoots (active xylem) becomes non functional after several years
heart wood
no longer transports water, but provide mechanical support, nutrient storage, contains resin so is more resistant to decay and darker
the cells produced by cork cadmium are called
cork
as cork cells mature, they come coated with?
Suberin
what is suberin
a waxy compound (non living cells) that protects cells against mechanical damage and entry of pathogens.
this layer impedes the diffusion of oxygen
suberin
lenticels
are regions of loosely packed cells in the cork that allow oxygen to diffuse into the stem
in gymnosperm, secondary xylem fulfills two roles of secondary growth
- provide tree with strength and stability
- transport water and nutrients from roots to leaves
tracheid or vessel fulfill both functions in gymnosperms wood?
tracheids
angiosperm wood, cells in secondary xylem mature into distinct types
- fibers
- vessel elements
fibers are?
thick cells with no lumen that provide support
root apical meristems
totipotent cells near the tip of roots produce new cells
after cell division, cells _______
alginate and differentiate
what protects the meristem and is rubbed off or damaged as root alongates?
root cap
auxin produced in shoot meristems transported _____ to roots via ____
down, phloem
as _____ moves through ______, it triggers formation of ________cells that become phloem and xylem
auxin, elongated zone, procamial
a single layer of cells just inside the endodermis from which new root meristems develop
pericycle
is transported from young developing leaves to differentiated vascular tissue.
auxin