Growth And Development

Question 1

– 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

Answer 1

Growth

Question 2

increase in size is commonly measured in one or
two directions, e.g. _________ and __________ of
the stem or
fruit

Answer 2

length; diameter

Question 3

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

Answer 3

dry weight

Question 4

• (or morphogenesis) growth and
  differentiation of cells into tissues, organs,
  and
  organisms

Answer 4

Development

Question 5

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

Answer 5

Cell growth and development

Question 6

– one mature cell divides into two
separate but equal daughter cells

Answer 6

cell division

Question 7

– each daughter cell
increases
volume or size after absorbing
water

Answer 7

cell enlargement

Question 8

– a cell after attaining its
final size or volume becomes specialized in
many ways

Answer 8

cell differentiation

Question 9

cell may divide in different planes

________ when the new cell wall of the
daughter cell is perpendicular to the
closest surface

Answer 9

anticlinal

Question 10

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)

Answer 10

periclinal

Question 11

-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

Answer 11

Phases of Plant Growth and Development

Question 12

> > determinate – plant grows up to a
certain
size, then stops to grow and
eventually dies
»
indeterminate – plant grows by
meristems
that continuously replenish
themselves

Answer 12

Types of growth:

Question 13

– plant grows up to a certain
size, then stops to grow and
eventually dies

Answer 13

determinate

Question 14

– plant grows by meristems
that continuously replenish
themselves

Answer 14

indeterminate

Question 15

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

Answer 15

Growth points

Question 16

: specialized tissues found in
various
parts of the plant (e.g. apical
and axial
shoot tips, root tips)

Answer 16

meristems

Question 17

: 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)

Answer 17

intercalary meristems

Question 18

: these generate cells that
lead to the expansion of width or
diameter of an organ (vascular

Answer 18

Lateral meristems

Question 19

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

Answer 19

Germination

Question 20

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

Answer 20

Primary Growth Patterns

Question 21

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

Answer 21

Primary Growth

Question 22

__________(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

Answer 22

Secondary Growth

Question 23

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

Answer 23

vascular cambium

Question 24

the inner face of the vascular cambium gives
rise to the _______ whereas the outer side
gives
rise to phloem

Answer 24

xylem

Question 25

xylem cells eventually form what we call “_____________”

Answer 25

annual
growth rings

Question 26

________ of the stem is composed of
tracheids, vessel elements and fibers

Answer 26

woody portion

Question 27

the _______ is composed of meristematic
cells
outside the secondary phloem
during secondary growth the epidermis derived
from
primary growth dries and separates
from the stem

Answer 27

cork cambium

Question 28

the cells in the outer cortex (outside the secondary
phloem) become meristematic and divide to form
cork cells on the outer perimeter – these cork
cells which deposit waxy materials (called _________)
in their cell walls form the periderm that
replaces
the epidermis

Answer 28

suberin

Question 29

the bark of a stem consists of the ___________and________

Answer 29

periderm and phloem

Question 30

plants acquire a characteristic shape or form by

correlated growth of component parts (e.g.

apical and lateral buds), that is, the growth from lateral buds can profoundly change plant shape and appearance component organs likewise show characteristic shape or form that persists in time and in
space (e.g. the shape of the leaves, the length
and breadth of the roots, etc)
growth correlations are manifested in many ways such as apical dominance, differentiation,
harvest index, shoot-to-root ratio, etc
growth correlation effects are largely associated with phytohormones, sometimes competition for growth factors (nutrients, water, radiation)

Answer 30

Growth Correlation

Question 31

these are events or oscillations occuring in
plants and are not triggered by
fluctuations of the environment
the three common rhythms in plants are:
circadian (every 24 hours), infradian
(every more than 24 hours) and
circannual (once a year)

Answer 31

endogenous rhythms

Question 32

– events that are repeatedly
occurring every 24 hours (e.g. closing and
opening of leaves and flowers – leaves of
Mimosa sp. open during the day and close
during the night – this event persists even if
the plant is exposed to continuous darkness
events or processes under the control of
circadian rhythm: gene transcription,
cytosolic Ca level, enzyme activities,
stomatal opening, leaf movement, hypocotyl
expansion, etc.

Answer 32

circadian rhythms

Question 33

these are light-detecting pigments in the leaves
that are thought to be involved in resetting
the internal biological clock of many plants

Answer 33

Phytochromes

Question 34

• this is the result of correlative inhibition of lateral
buds by the apex
• correlative inhibition is associated with complete
or partial retardation of mitotic activity in the
meristem of the lateral bud
• excision of the apical portion of the stem is a
simple method of eliminating correlative inhibition
• indoleacetic acid (IAA) and cytokinin are believed
to play a role in correlative inhibition

Answer 34

Apical Dominance

Question 35

• this is initiated in certain “separation” layers which
are genetically limited to specific locations
called abscission zones
mineral deficiencies, drought, low radiation flux
may also trigger floral and fruit abscission
• abscissic acid (ABA) has been also implicated in
abscission

Answer 35

Abscission

Question 36

▪ hormones (or phytohormones) are organic
compounds synthesized in plants that at low
concentrations affect cell or plant growth and
development
▪ unlike animal hormones, plant hormones can act on
adjacent cells as well as distant cells

Answer 36

Growth Regulation (by hormones)

Question 37

_____ – this hormone is synthesized in shoot apical
meristems
✔ promotes cell elongation in stems and in
coleoptiles
✔ promotes development of lateral roots
✔ participates in stem and root growth responses to
light and gravity
✔ inhibits lateral bud growth thus it promotes
apical dominance
✔ stimulates differentiation of the vascular tissue
into phloem and xylem
✔ promotes root initiation
✔ delays fruit ripening
✔ promotes femaleness in dioecious flowers

Answer 37

auxin

Question 38

___________ – more than 70 gibberellic acids (GAs)
have been identified; the most widely
available
is GA3 but GA1is the most important in plants
✔ GA3 was extracted from a fungus
✔ GA1 is synthesized in the meristematic tissues in
the shoot and in developing seeds
✔ GA1 is transported in the plant via the phloem and
xylem
✔ promotes stem elongation
✔ stimulates cell division and elongation
✔ promotes bolting in long-day plants
✔ induces seed germination after stratification
✔ induce maleness in dioecious flowers

Answer 38

gibberellin

Question 39

in the absence of auxin, cytokinin is capable of inducing cell division in plant tissue cultures

this hormone is synthesized in root tips and in developing seeds

transported from the roots to the shoot via the

xylem promotes sprouting of buds when it is in

proper balance with auxin

promotes leaf expansion retards leaf aging

0 prolongs life of stored vegetables and cut

flowers

Answer 39

cytokinin

Question 40

☐ generally considered as a growth inhibitor

site of synthesis: mature leaves particularly

when the plant is exposed to drought

transported from leaves to the seeds and

roots via phloem

inhibits cell growth

☐ helps prevent water loss by inducing

stomatal closure

induces transport of photosynthates to

developing seeds

induces synthesis of storage proteins in

seeds

24

promotes seed and bud dormancy

☐ when applied to nursery stocks before shipment, this hormone maintains dormancy and increases capacity of the stock to resist damage

Answer 40

abscisic acid

Question 41

this gaseous hormone is synthesized in various tissues particularly those that are senescing and ripening

transported mainly by diffusion

☐stimulates fruit ripening promotes abscision of leaves, flowers and

fruits induces femaleness in dioecious flowers

Answer 41

ethylene