Plant Growth And Development Flashcards
Growth is regarded as…
Fundamental and visible(conspicuous)character of organisms
It is accompanied by 1….2…..
Catabolic and anabolic processes
Growth?
Growth is an irreversible permanent increase in size of an organ or its parts or even a single cell
Growth occur at an expense of….
Energy
Plant growth indeterminate/determinate?
Indeterminate
The growth is unique because
Plants retain the capacity for unlimited growth throughout their life.
This ability of the plants is due to the presence
of ……at certain locations in their body
This ability of the plants is due to the presence
of meristems at certain locations in their body
The cells of such meristems
have the capacity to …… and self……
The cells of such meristems
have the capacity to divide and self-perpetuate.
The product which looses the capacity to divide such cells make up?
The product, however,
soon loses the capacity to divide and such cells make up the plant body.They differentiate and mature.
Open form of growth ?
This form of growth wherein new cells are always being added to the
plant body by the activity of the meristem is called the open form of growth.
Shoot and root apical meristems are principlly responsible
primary growth of the plants
Shoot and root apical meristems principally contribute?
to the elongation of the plants along
their axis. Means increase in girth of dicot root and dicot stem.
In dicotyledonous plants and gymnosperms 1…2…3…appear later in life?
lateral meristems,
vascular cambium and cork-cambium appear
later in life.
Meristems which cause increase in girth In later life of a plant? In which they are active/not active ?
lateral meristems,
vascular cambium and cork-cambium that cause
the increase in the girth of the organs in which
they are active.
Growth, at a cellular level, is principally a
consequence of
increase in the amount of
protoplasm.
Growth is, therefore,
measured by a variety of parameters some of
which are:1 2 3 4 5 6 ?
1) increase in fresh weight
2) dry weight,
3)length
4) area
5) volume
6) cell number.
expressed as increase in cell number;
one single maize
root apical mersitem can give rise…
to more than
17,500 new cells per hour
cells in a
watermelon may increase in size by upto
3,50,000 times
In the former, growth is
expressed as increase in…
increase in cell number
The latter expresses growth as
expresses growth as increase in size of the cell.
While the growth of a pollen tube is measured
in terms of its…
length
Increase in surface area
denotes the growth in …
dorsiventral leaf
The period of growth is generally divided into
three phases…
meristematic
elongation
maturation
The
constantly dividing cells, both at the root apex
and the shoot apex, represent the
meristematic
phase of growth
The cells in meristematic region are rich in…
protoplasm
The cells of meristematic region posses..
possess large conspicuous
nuclei
The cell walls of meristematic region are…in nature 1…2..with..3
primary in nature,thin and cellulosic with abundant
plasmodesmatal connections
The cells
proximal (just next, away from the tip) to the
meristematic zone represent the
phase of elongation.
1..2..3..are the
characteristics of the cells in elongation phase.
Increased
vacuolation, cell enlargement and new cell wall deposition
Further away from the apex, i.e.,
more proximal to the phase of elongation, lies the…. which is
undergoing the phase of….
Further away from the apex, i.e.,
more proximal to the phase of elongation, lies the portion of axis which is
undergoing the phase of maturation
The cells of meristematic zone, attain their
maximal size in terms of 1….nd 2…
wall thickening and protoplasmic modifications.
Most of the tissues and cell types represent …
Maturation phase.
Growth rate?
The increased growth per unit time is termed as growth rate.
Growth rate is expressed mathematically
Possible
An organism, or a part of the
organism can produce more cells in a variety of ways. a and b
(a) Arithmetic
(b) Geometric growth
The growth rate shows an increase that may be
1..or..2..
arithmetic
or
geometrical
In arithmetic growth, following mitotic cell
division
1)how many cells divide?
2)other cells 1)…&..2)…
1) only one daughter cell continues to divide
2)while the other differentiates and matures.
The
simplest expression of arithmetic growth is
exemplified by…
a root elongating at a constant rate.
On plotting the length of the
organ against time graph which type of curve is obtained?
linear curve is obtained
Mathematically, arithmetic growth expressed as…
Lt=L0 + rt
In eqn Lt= L0 + rt
Lt=?
L0= ?
r =?
Lt= L0 + rt
Lt= length at time ‘t’
L0 = length at time ‘zero’
r = growth rate / elongation per unit time
In most systems, the initial growth is ….
(lag phase), and it increases rapidly thereafter – at
…….
In most systems, the initial growth is slow
(lag phase), and it increases rapidly thereafter –* at
an exponential rate (log or exponential phase). *
Here,
both the progeny cells following mitotic cell division
retain the ability to ….and continue to….
Here,
both the progeny cells following mitotic cell division
retain the ability to divide and continue to do so.
However, with limited nutrient supply, the growth
…. leading to …… phase.
However, with limited nutrient supply, the growth
Slows down leading to a stationary phase.
If we plot
the parameter of growth against time, we get a typical….curve
sigmoid or S-curve
sigmoid curve
is a characteristic of living…
organism growing in a
natural environment.
It is typical for all cells, tissues
and organs of a plant.
exponential growth can be expressed as by eqn…
W1= W0 ert
W1= W0 ert here
W1= ?
W0 = ?
r = ?
t = ?
e=?
W1= final size (weight, height, number etc.)
W0 = initial size at the beginning of the period
r = growth rate
t = time of growth
e=?
e = base of natural logarithms
Here, r is the relative growth rate and is also the
measure of the ability of the plant to produce new
plant material, referred to as efficiency index.
efficiency index?
measure of the ability of the plant to produce new
plant material, referred to as efficiency index.
Final size of w1 depends on?
Wo= initial size
Quantitative comparisons between the growth of living system can
also be made in two ways :
(i)absolute growth rate. (ii) Relative Growth Rate
1)Absolute growth rate?
measurement and the comparison of total
growth per unit time is called the absolute growth rate.
2)Relative growth rate ?
The growth of
the given system per unit time expressed on a common basis, e.g., per
unit initial parameter is called the relative growth rate.
Essential elements for growth…1…2…&…3…
water
oxygen
&
nutrients
The plant cells grow in size by cell enlargement which
in turn requires ….
water
Turgidity of cells helps in …
Extension growth
Thus,
plant growth and further development is intimately linked ….
to the water
status of the plant
Water also provides the medium for ….
needed for …..
Water also provides the medium for enzymatic activities
needed for growth.
Oxygen helps in releasing metabolic energy essential
for ….
growth activities.
Nutrients (macro and micro essential elements) are
required by plants for the synthesis of ….and act as source of
….
synthesis of protoplasm and act as source of
energy.
every plant organism has an optimum ……
best suited for its growth.
temperature range
Any ….. from this range could be
…..
Deviation, detrimental for survival
Environmental signals such as …&…
also affect certain phases/stages of growth.
light and gravity
The cells derived from root apical and shoot-apical meristems and
cambium differentiate and mature to
perform specific functions.
differentiation=?
The cells derived from root apical and shoot-apical meristems and
cambium differentiate and mature to perform a specific function. This act leading to maturation is called diffentiation.
During differentiation,
cells undergo few to major … both in their … and …
structural changes
cell walls and
protoplasm.
For example, to form a tracheary element, the cells would
lose their protoplasm ex of?
Ex of differentiation
They also develop a very strong, elastic
…..carry water to long distances even
under ….
lignocellulosic secondary cell walls, extreme tension.
Dedifferentiation?
The living differentiated
cells, that by now have lost the capacity to divide can regain the capacity
of division under certain conditions. This phenomenon is termed as dedifferentiation
For example, formation of meristems – interfascicular
cambium and cork cambium from fully differentiated parenchyma cells.
Ex of ?
Dedifferentiation
.
redifferentiation?
such meristems/tissues are able to divide and produce
cells that once again lose the capacity to divide but mature to perform
specific functions, i.e., get redifferentiated.
tissues in a
woody dicotyledenous plant that are the products of redifferentiation.
growth in plants
is open, i.e., it can be
…
it can be indeterminate or determinate.
cells positioned away from root apical
meristems differentiate as ….
root-cap cells
even differentiation in plants is open, because
because cells/tissues arising out of
the same meristem have different structures at maturity.
The final
structure at maturity of a cell/tissue is also determined by the …
location of
the cell within.
cells positioned away from root apical
meristems differentiate as
Root cap cells
while those pushed to the
periphery mature as …
epidermis.
Development?
Development is a term that includes all changes that an organism goes
through during its life cycle from germination of the seed to senescence.
Plasticity,?
Plants follow different pathways in response to environment or phases
of life to form different kinds of structures. This ability is called plasticity.
Plasticity ex
1
2
3
1)heterophilly in cotton
2)coriander
3)larkspur
In such plants, the
leaves of the … are different in shape from those in … plants
juvenile plant,
mature
plants
difference in shapes of leaves produced in air
and those produced in water in buttercup also ….
represent the
heterophyllous development due to environment
phenomenon of heterophylly is an example of ….
plasticity
…, ..and… are very closely related
events in the life of a plant.
growth, differentiation and development
Development in plants (i.e., both growth
and differentiation) is under the control of …and… factors.
intrinsic and extrinsic
Intrinsic factors
includes both intracellular (genetic) or intercellular factors
(chemicals such as plant growth regulators)
Extrensic factors
light,
temperature,
water,
oxygen,
nutrition, etc
The plant growth regulators (PGRs) are small, simple molecules of diverse
…..composition.
diverse
chemical composition.
Plant growth regulators
indole compounds
adenine derivatives
derivatives of carotenoids
terpenes
gases
Indole compounds
(indole-3-acetic
acid, IAA)
adenine derivatives
(N6-furfurylamino purine, kinetin),
derivatives of carotenoids
(abscisic acid, ABA)
terpenes
(gibberellic acid,GA3)
gases
(ethylene, C2H4).
Plant growth regulators are variously
described as
plant growth substances, plant hormones or phytohormones
in literature.
The PGRs can be broadly divided into two groups based on their
functions in a living plant body.
Plant growth promoter and plant growth inhibitor
Plant growth promoters
1Auxin
2Gibberelline
3Cytokinine
Growth promoting activities 1-7
1.Cell division
2.Cell enlargement
3.Pattern formation
4.Tropic growth
5.Flowering
6.Fruiting
7.Seed form
Plant growth inhibitor
1.Abscissic acid (carotenoid)
2.ethylene
Growth inhibiting activities
1.Dormancy
2.Abscisaion
The PGRs of the other group play an important role in plant responses to …
responses to wounds and stresses of biotic and abiotic origin.
The gaseous
PGR, ethylene, could fit either of the groups, but it is …
largely an inhibitor
of growth activities.
the discovery of each of the five
major groups of PGRs have been …
accidental.
Charles Darwin and his son Francis Darwin used which plant for their experiment of phototropism?
Canary grass
the coleoptiles of canary grass
responded to ….
unilateral illumination by
growing towards the light source
(phototropism)
(phototropism)
growing towards the light source
it was concluded that the tip of coleoptile was
the site of
transmittable influence
transmittable influence caused
Bending of the entire coleoptile
Conclusion of experiment of phototropism is…
They proved bending due to a chemical substance but failed to give the name to that substance
Auxin was isolated by …
F.W. Went
Auxin was isolated by f.w went from tips of coleoptiles of
oat seedlings.
Auxins (from Greek ‘auxein’ :
to grow)
Auxin was first isolated from
human urine.
The term ‘auxin’ is applied to the
indole-3-acetic acid (IAA)
and to other
natural and synthetic compounds having certain growth regulating
properties.
They are generally produced by the
growing apices of the stems
and roots,
from where they migrate to the regions of
their action.
Auxins like…and… have been isolated from plants.
IAA and indole butyric acid (IBA)
…and…
are synthetic auxins.
NAA (naphthalene acetic acid) and 2, 4-D (2, 4-dichlorophenoxyacetic)
All these auxins have been used extensively in …and…
agricultural and horticultural practices.
Auxin help to initiate rooting in …
stem cuttings
stem cuttings, an application widely used for …
used for plant propagation.
Auxins promote flowering in..
Pineapples
They help to prevent ….and …drop at …. stages
Fruit and leaf drop at early stages
but promote the
…of …leaves nd fruits
abscission older mature leaves and fruits
Apical dominance is observed in
Higher plants
Apical Dominance
In most higher plants, the growing apical bud inhibits the growth of
the lateral (axillary) buds, a phenomenon called apical dominance.
Removal of shoot tips (decapitation) usually results
in the growth of lateral
buds also cause hedge formation due to this
Auxins also induce par…..
Parthenocarpy
Eg of parthenocarpy shown by auxin
Tomatoes
Auxins are widely used as
herbicides.
…widely used to kill dicotyledonous
weeds, does not affect … plants.
2, 4-D[2,4 dichlorophenoxy acetic acid] and 2,4,5-T[2,4,5,Trichlorophenoxy acetic acid] ,mature
monocotyledonous
…. used to prepare
weed-free lawns by gardeners.
Auxin
Auxin also
controls xy….
Xylem differentiation
Auxin also help in
cell division
Auxin prevents premature
fall of leaf
Bonsai formation
Tall trees are restricted to short height and increase girth promoting branching also achieved by cutting tips
Gibberellins are another kind of
promotory
PGR.
There are more than… gibberellins reported from widely different organisms such…and…
100..,
as fungi and higher plants.
They are denoted
as
GA1
, GA2
, GA3
and so on.
…was one of the first
gibberellins to be discovered
Gibberellic acid (GA3
)
Most studied gibberellic acid is
GA3
All GAs are
…
acidic
They produce a wide range of … in the plants.
physiological responses
Their ability to cause an increase in length of axis is used to increase the….
length of grapes stalks.
Gibberellins, cause fruits like … to …
and improve its …
Apple,elongate, shape
They also delay … Thus, the fruits can
be left on the tree longer so as to …
senescence,
extend the market period.
GA3 is used to
speed up the ..
malting process in brewing industry.
Sugarcane stores … as sugar in their ..
carbohydrate,stems
Thus,
increasing the yield by as much as
20 tonnes per acre.
Spraying juvenile conifers with GAs …. period, thus
leading to …
hastens the maturity,
early seed production.
Gibberellins also promotes bolting
(internode elongation just prior to flowering) in
beet,
cabbages
and
many
plants with rosette habit.
Bakanae disease also called
Foolish seedlings
Bakanae disease is a disease of ?
Rice seedlings
Bakanae disease was caused by
Fungus called gibberella fujikuroi
Bakanae disease was caused by
E.kurosawa 1926
Symptoms if disease were appeared when treated with …
sterile filter ate of fungus
The active substance later identified was
Gibberellic acid