Growth And Development Flashcards
– increase in volume (or size), weight,
number of cells
increase in size is commonly measured in one or
two directions, e.g. length and diameter of
the stem or
fruit; increase in area and
thickness of leaves
increase in dry weight is a more valid indicator of
growth than fresh weight because tissues,
organs highly vary in terms of moisture content
sometimes
increase in dry weight is an
inadequate
indicator of growth, e.g. seeds
germinated in
the dark show lower biomass
than the original weight of the seed due to
respiratory loss of CO2 despite the differentiation
of the shoot and root primordia
Growth
increase in size is commonly measured in one or
two directions, e.g. _________ and __________ of
the stem or
fruit
length; diameter
increase in __________ is a more valid indicator of
growth than fresh weight because tissues,
organs highly vary in terms of moisture content
sometimes
increase in dry weight is an
inadequate
indicator of growth, e.g. seeds
germinated in
the dark show lower biomass
than the original weight of the seed due to
respiratory loss of CO2 despite the differentiation
of the shoot and root primordia
dry weight
- (or morphogenesis) growth and
differentiation of cells into tissues, organs,
and
organisms
Development
Events: cell division, cell enlargement, cell
differentiation
cell division – one mature cell divides into two
separate but equal daughter cells
cell enlargement – each daughter cell
increases
volume or size after absorbing
water
cell differentiation – a cell after attaining its
final size or volume becomes specialized in
many ways
Cell growth and development
– one mature cell divides into two
separate but equal daughter cells
cell division
– each daughter cell
increases
volume or size after absorbing
water
cell enlargement
– a cell after attaining its
final size or volume becomes specialized in
many ways
cell differentiation
cell may divide in different planes
________ when the new cell wall of the
daughter cell is perpendicular to the
closest surface
anticlinal
cell may divide in different planes
_____________ when the new cell wall of the
daughter cell is parallel to the closest
surface (e.g. parallel to the surface of
the shoot or root)
periclinal
-Germination
-Seedling phase
-Juvenile phase: rapid vegetative growth;
flowering cannot be induced
-mature vegetative phase: flowering can be
induced or it can naturally occur
during
this phase
-reproductive phase: series of events that
starts
with flower initiation and ends
with
physiological maturity of the
seeds or
fruits
-senescence: final phase of growth
characterized by changes that
lead
sooner or later to death of the
whole or
part of the plant
Phases of Plant Growth and Development
> > determinate – plant grows up to a
certain
size, then stops to grow and
eventually dies
»
indeterminate – plant grows by
meristems
that continuously replenish
themselves
Types of growth:
– plant grows up to a certain
size, then stops to grow and
eventually dies
determinate
– plant grows by meristems
that continuously replenish
themselves
indeterminate
meristems: specialized tissues found in
various
parts of the plant (e.g. apical
and axial
shoot tips, root tips)
intercalary meristems: tissues between
differentiated tissues, e.g. basal
region
of the internode of grasses,
region
between leaf
sheath and
leaf blade
(responsible for the
extension of leaf
length)
lateral meristems: these generate cells that
lead to the expansion of width or
diameter of an organ (vascular
Growth points
: specialized tissues found in
various
parts of the plant (e.g. apical
and axial
shoot tips, root tips)
meristems
: tissues between
differentiated tissues, e.g. basal
region
of the internode of grasses,
region
between leaf
sheath and
leaf blade
(responsible for the
extension of leaf
length)
intercalary meristems
: these generate cells that
lead to the expansion of width or
diameter of an organ (vascular
Lateral meristems
Growth in seeds
– resumption of growth of the
embryo which is in a state of arrested
development
affected by: daylight hours, water, soil
temperature, oxygen, and in some species
solar radiation
starts with imbibition of water that leads to the
rupture of the seed coat thus facilitating the
entry of oxygen and aerobic metabolism
this is followed by the activation of the cells of
the root primordium leading to cell division,
elongation and differentiation
primary root then breaks through the seed coat
– this marks the end of germination
the cells of the shoot primordium are likewise
activated followed by cell division,
elongation and differentiation
the emergence of the coleoptile follows – this
completes the process of germination
Germination
capacity of an organ to grow – determined by rate
of cell division and enlargement
water uptake leads to cell enlargement
deposition of polysaccharides in the cell wall leads
to cell thickening
cell division at specific planes and cell expansion
at
specific directions are caused by selective
gene expression – this leads further to
variations in organ shape and function
Primary Growth Patterns
Growth in Plants
this occurs in apical meristems (e.g. shoot and
root tips)
lateral roots develop from the pericycle where a
clump of cells elongates and then pushes
out through the root cortex
Primary Growth
__________(in woody plants)
this occurs in lateral meristems like vascular
and
cork cambia (singular: cambium)
all gymnosperms (mostly in dicots; rarely in
monocots) exhibit secondary growth
Secondary Growth
the ______________ is composed of
parenchyma cells (cells that retain their
ability
to divide) – these cells divide into two
daughter cells wherein one daughter cell
differentiates while the other remains
meristematic
vascular cambium
the inner face of the vascular cambium gives
rise to the _______ whereas the outer side
gives
rise to phloem
xylem
