Transcript growth and development_oxf

1
parent plant
single cells
2
dish with nutrients
cell masses
3
small plants
adult plants
4
They are identical
to the parent plant.
5
1
What process does
the single plant cell
undergo to form a
mass of cells
6
2
How do the
unspecialized cells
give rise to a whole
plant
7
14.1 Concepts of growth
and development
growth
(生長)
development
complex
zygote
(發育)
multicellular
adult
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14.1
Concepts of growth and development
Growth
• an irreversible increase in size and
dry mass
• brought by:
1 Cell division
mitotic cell
division
increase in number
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14.1
Concepts of growth and development
Growth
• an irreversible increase in size and
dry mass
• brought by:
2 Cell enlargement
synthesis of
new materials
increase in size
10
14.1
Concepts of growth and development
Development
• an irreversible change in form and
increase in complexity
• brought by differentiation of cells
formation of specialized cells
to carry out different functions
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14.1
Concepts of growth and development
Development
• cells
tissues
organs
systems
• growth occurs at the same time
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14.1
Concepts of growth and development
Growth and development in
humans
Growth
Cell division
first mitotic
cell division
zygote
second mitotic
division
daughter
cells
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14.1
Concepts of growth and development
Growth and development in
humans
Growth
Cell division
Cell enlargement
repeated
divisions
a ball of cells
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14.1
Concepts of growth and development
Growth and development in
humans
Development
Cell differentiation
differentiate
red blood cells
cardiac muscle
cells
nerve cells
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14.1
Concepts of growth and development
Growth and development in
humans
Development
(increase in complexity)
similar cells
group together
tissues
organs
systems
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14.1
Concepts of growth and development
1a Growth is the irreversible increase
in size and dry mass of an
organism.
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14.1
Concepts of growth and development
1b Development is the irreversible
change in form and the increase
in complexity of an organism.
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14.1
Concepts of growth and development
2 Growth results from
cell division
and cell enlargement .
Mitotic cell division increases the
number of cells and cell
number
enlargement increases the size
of cells.
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14.1
Concepts of growth and development
3a Development results from
differentiation
differentiation of cells.
process of forming specialized
cells to carry out different
functions
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14.1
Concepts of growth and development
3b Similar types of specialized cells
group together to form tissues ,
organs
organs and systems .
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Growth and development in plants
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Dicot vs Monocot Seeds
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Seed Germination
seed
seedling
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Seed Germination
seed
seedling
dormancy
active grow
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Seed maturation involves dehydration
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Seed germination
Water during seed development, dormancy
and germination
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Seed germination
Water during seed development, dormancy
food reserve
and germination
water
embryo
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Seed germination
Water during seed development, dormancy
food reserve
and germination
water
embryo
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Seed germination
Water during seed development, dormancy
food reserve
and germination
water
embryo
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Seed (dicot) Germination
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X
Y
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c. In terms of the change in dry mass
during seed germination (before leaves
emerge), what kind of growth is
demonstrated?
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Where does growth and development
take place in plants?
34
14.2
Growth and development in plants
Regions of growth and
development
growth only happens in
meristems (分生組織)
a group of
undifferentiated cells
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14.2
Growth and development in plants
Regions of growth and
development
growth only happens in apical meristem
meristems (分生組織)
lateral meristem
able to divide by mitotic
cell division throughout
the plant’s life
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14.2
Growth and development in plants
Regions of growth and
development
shoot tip
apical meristem
• tips of roots and
shoots
• increase in
length
• primary growth
(初生生長)
root tip
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14.2
Growth and development in plants
Regions of growth and
development
lateral meristem
• periphery of
stems and roots
• increase in
thickness
• secondary growth
(次生生長)
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14.3 Measurement of growth
I record its height every
day. Do you know how
many parameters we
can use to measure the
growth of an organism?
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14.3
Measurement of growth
1 Size
By measuring …
a length or height
suitable for organisms
or structures which
grow mainly by
elongation
e.g. length of root
of a seedling
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14.3
Measurement of growth
1 Size
By measuring …
b surface area
suitable for flat
structures
transparent grid
paper
e.g. surface area
of a leaf
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14.3
Measurement of growth
1 Size
By measuring …
c volume
suitable for
structures with
irregular shapes
change in volume
= volume of pear
e.g. fruit
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14.3
Measurement of growth
1 Size
Advantages
• organisms remain alive, allowing
continuous measurement
• easy and convenient
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14.3
Measurement of growth
1 Size
Disadvantage
• measured in one dimension, growth in
other dimension is ignored
e.g. shrub may
grow laterally
without any
increase in
height
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14.3
Measurement of growth
2 Fresh mass
= total mass under normal conditions
(including water)
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14.3
Measurement of growth
2 Fresh mass
Advantages
• organisms remain alive, allow
continuous measurement
• easy and
convenient
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14.3
Measurement of growth
2 Fresh mass
Disadvantage
• affected by water content, leads to
great variation
affected by environmental
conditions and behaviour of
organisms
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14.3
Measurement of growth
3 Dry mass
= mass when all water is removed from
the organism’s body
= mass of organic matter present
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14.3
Measurement of growth
3 Dry mass
oven slightly
above 100°C
constant
mass is
obtained
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14.3
Measurement of growth
3 Dry mass
Advantage
• Not affected by water content of
organisms
• which fluctuates a lot due to
environmental conditions
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14.3
Measurement of growth
3 Dry mass
Disadvantages
• organisms are killed after measurement
• Cannot make continuous
measurement
large sample
size is needed
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14.3
Measurement of growth
3 Dry mass
Disadvantages
• time-consuming, not suitable for large
organisms
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14.3
Measurement of growth
Parameter for measuring growth:
size
i.e. measuring length, height ,
surface area and volume
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14.3
Measurement of growth
Parameter for measuring growth:
size
Advantage:
• The organism remains alive ,
so its growth can be measured
continuously
• Easy and convenient
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14.3
Measurement of growth
Parameter for measuring growth:
size
Disadvantage:
• Size is measured in one
dimension, growth in other
dimension can / cannot be
taken into account
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14.3
Measurement of growth
Parameter for measuring growth:
fresh mass
i.e. measuring mass with water
retained
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14.3
Measurement of growth
Parameter for measuring growth:
fresh mass
Advantage:
• The organism remains alive ,
so its growth can be measured
continuously
• Easy and convenient
57
14.3
Measurement of growth
Parameter for measuring growth:
fresh mass
Disadvantage:
• Affected by water content
which varies with different
environmental conditions and
behaviour of the organism
behaviour
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14.3
Measurement of growth
Parameter for measuring growth:
dry mass
i.e. measuring mass with water
removed
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14.3
Measurement of growth
Parameter for measuring growth:
dry mass
Advantage:
• An accurate method to
measure the amount of organic
matter in an organism
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14.3
Measurement of growth
Parameter for measuring growth:
dry mass
Disadvantage:
• The organism is killed , so its
growth can / cannot be
measured continuously
• A large number of specimen is
needed
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14.3
Measurement of growth
Parameter for measuring growth:
dry mass
Disadvantage:
• Time-consuming
• Not suitable for large
organisms
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14.4 Growth curves
I have recorded the length of the main
roots of young seedlings for a week.
How should I present the data?
Use a growth curve.
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S-shaped growth curve
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14.4
Growth curves
Growth curves of annual
plants
annual plant (一年生植物)
• lives for only one growing season
• growth curve has 3 stages and
an S-shape
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14.4
Growth curves
Growth curves of annual
stage 1
plants
50
Stage 1
40
Stored food is
broken down to 30
provide energy 20
for growth
10
dry mass
decreases
0
dry mass (g)
5 10 15 20 2566
time (weeks)
14.4
Growth curves
Growth curves of annual
stage 1
2
plants
50
Stage 2
40
Green leaves
30
are formed to
make food by
20
photosynthesis
10
dry mass
increases
0
dry mass (g)
5 10 15 20 2567
time (weeks)
14.4
Growth curves
Growth curves of annual
stage 1
2
plants
50
Stage 2
40
Green leaves
30
are formed to
make food by
20
photosynthesis
10
mass
ratedry
of photosynthesis
> rate of respiration
increases
0 > consumption
food production
5 10 15 20 2568
dry mass (g) time (weeks)
14.4
Growth curves
Growth curves of annual
stage 1
2
plants
50
Stage 3
3
40
Dispersal of
fruits and seeds 30
dry mass
20
decreases
10
0
dry mass (g)
death
5 10 15 20 2569
time (weeks)
14.4
Growth curves
body weight / height
Growth curves of humans
birth
0
foetal growth
age
(years)
70
14.4
Growth curves
body weight / height
Growth curves of humans
rapid growth
03
infancy (嬰兒期)
age
(years)
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14.4
Growth curves
body weight / height
Growth curves of humans
growth slows down
03
13
childhood (兒童期)
age
(years)
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14.4
Growth curves
body weight / height
Growth curves of humans
03
13
18
adolescence (青年期)
rapid growth
age
(years)
73
14.4
Growth curves
body weight / height
Growth curves of humans
height remains steady
03
13
18 65
adult stage (成年期)
age
(years)
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14.4
Growth curves
body weight / height
Growth curves of humans
cell division
still occurs to
replace worn
out cells
age
(years)
03
13
18 65
adult stage (成年期)
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14.4
Growth curves
body weight / height
Growth curves of humans
death
negative
growth
03
age
(years)
13
18 65
old stage (衰老期)
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14.4
Growth curves
Growth rates of different body
parts
Different body parts
also grow at different
times and different
rates.
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14.4
Growth curves
Growth rates of different body
parts
relative growth
rate (%)
100
80
60
40
20
0
whole body
5
10
15
age
(years)
78
20
Our body
proportion
changes as
we grow
79
80
14.4
Growth curves
Growth rates of different body
parts
relative growth
rate (%)
100
80
60
40
20
0
brain
rapid growth during infancy
and early childhood
whole body
5
10
15
age
(years)
81
20
14.4
Growth curves
Growth rates of different body
parts
relative growth
rate (%)
100
80
brain
60
40
20
0
whole body
5
10
rapid
growth at
puberty
reproductive
organs
age
(years)
82
15
20
14.4
Growth curves
Growth rates of different body
parts
9-week new- 2 yrs 5 yrs 13 yrs 22 yrs
foetus born
head grows rapidly at early stage
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14.4
Growth curves
Growth rates of different body
parts
9-week new- 2 yrs 5 yrs 13 yrs 22 yrs
foetus born
relative size decreases with age
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14.4
Growth curves
Growth rates of different body
parts
9-week new- 2 yrs 5 yrs 13 yrs 22 yrs
foetus born
limbs grow slowly at early stage
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14.4
Growth curves
Growth rates of different body
parts
9-week new- 2 yrs 5 yrs 13 yrs 22 yrs
foetus born
relative size increases with age
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14.4
Growth curves
Growth rates of different body
parts
9-week new- 2 yrs 5 yrs 13 yrs 22 yrs
foetus born
trunk grows at a rate proportional to
87
14.4
Growth curves
Growth rates of different body
parts
9-week new- 2 yrs 5 yrs 13 yrs 22 yrs
foetus born
the rate of whole body
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14.4
Growth curves
Growth rates of different body
parts
9-week new- 2 yrs 5 yrs 13 yrs 22 yrs
foetus born
relative size remains the same
89
14.4
Growth curves
Growth rates of different sexes
body mass (kg)
60
50
40
30
20
10
boys
girls
different rates during
adolescence
age (years)
90
0 2 4 6 8 10 12 14 16 18
14.4
Growth curves
Growth rates of different sexes
body mass (kg)
60
50 girls reach
40 puberty earlier
30
20
10
age (years)
91
0 2 4 6 8 10 12 14 16 18
14.4
Growth curves
Growth rates of different sexes
body mass (kg)
60
50
40
30
20
10
boys grow faster than girls at
adolescence
girls reach puberty
earlier
0 2 4 6 8 10 12 14 16 18
age (years)
92
14.4
Growth curves
Growth rates of different sexes
body mass (kg)
60
50
40
30
20
10
boys grow faster than girls
girls reach puberty
earlier
girls grow faster than
boys
0 2 4 6 8 10 12 14 16 18
boys
girls
age (years)
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Different kinds of growth curves
Absolute growth
Absolute growth rate
Relative growth rate
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Growth patterns
Isometric Growth
95
Growth patterns
Allometric Growth – growth with a change
in relative proportion of body parts
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• Growth patterns
Limited vs unlimited Growth in human
height
age
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Growth patterns
Limited vs Unlimited Growth in some fish
catfish
98
Growth curve in annual plants
Sunflower plant in bloom
99
Growth curve in annual plants
3
1
2
4
100
Growth curve in annual plants
Rapid vegetative
flower, seed, fruit
growth
formation
seed dispersal
Seed germination
and death
101
Growth patterns
Limited vs unlimited growth in perennial plants
102
Growth curve in perennial
plants
103
14.4
Growth curves
1 Growth stages of annual plants:
Dry mass decreases during the
early stage of germination
because the stored food is
broken
brokendown
down to provide energy
for growth.
104
14.4
Growth curves
1 Growth stages of annual plants:
Dry mass increases after green
green
leaves
leaves are produced because
food production is faster than
food consumption.
105
14.4
Growth curves
1 Growth stages of annual plants:
Dry mass decreases when the
plant disperses its fruits and
seeds
seeds .
106
14.4
Growth curves
2 Growth occurs in
all parts of the
human body.
107
14.4
Growth curves
3 Growth stages in humans:
Growth occurs rapidly during
infancy.
108
14.4
Growth curves
3 Growth stages in humans:
Growth then slows down during
childhood and becomes rapid
again in adolescence.
109
14.4
Growth curves
3 Growth stages in humans:
A person reaches the maximum
size in adulthood .
110
14.4
Growth curves
3 Growth stages in humans:
Growth becomes negative
during the old stage.
111
14.4
Growth curves
4 Relative sizes of different body parts
change with age because they have
different
different growth rates.
112
14.4
Growth curves
5 Girls enter puberty earlier
than
boys, therefore girls have a faster
growth rate than boys during the
early stage of adolescence.
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14.2 Growth and development
in plants
I still don’t understand
‘growth’ and ‘development’.
Let’s discuss the
situation in
plants.
114
14.2
Growth and development in plants
Seed germination
process by which a seed
germination
grows and develops into
(萌發)
a seedling
115
14.2
Growth and development in plants
Seed germination
radicle
seed coat
Day 2
The radicle emerges.
mung bean seed
water
116
14.2
Growth and development in plants
Seed germination
seed cut open
117
14.2
Growth and development in plants
Seed germination
Day 2
1 Seed absorbs water through the
micropyle and the seed coat breaks.
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14.2
Growth and development in plants
Seed germination
Day 2
2 Insoluble food in cotyledons is
converted to soluble form by enzymes.
119
14.2
Growth and development in plants
Seed germination
Day 2
3 Soluble food is transported to the
plumule and radicle for growth and
development.
120
14.2
Growth and development in plants
Seed germination
radicle
Day 3
Root hairs increase
the surface area for
absorbing water and
minerals.
root hairs
121
14.2
Growth and development in plants
Seed germination
hooked hypocotyl (下胚軸)
Day 4
The hypocotyl
elongates and brings
the cotyledons up.
plumule tip protected
by cotyledons
122
14.2
Growth and development in plants
Seed germination
hypocotyl
Day 5
The hypocotyl
straightens.
123
14.2
Growth and development in plants
Seed germination
hypocotyl
Day 5
The cotyledons carry
out photosynthesis for
a few days.
cotyledons turn green
124
14.2
Growth and development in plants
Seed germination
young leaves
Day 6
Young leaves develop
to make food by
photosynthesis.
Cotyledons fall off.
cotyledons
125
14.2
Growth and development in plants
Conditions for seed
germination i) Water
a softens seed coat and
makes cotyledons swell
seed coat breaks,
radicle can emerge
126
14.2
Growth and development in plants
Conditions for seed
germination i) Water
b activates enzymes
help convert insoluble
food reserves into
simpler and soluble
forms for growth
127
14.2
Growth and development in plants
Conditions for seed
germination i) Water
c acts as a solvent
transports soluble food
to growing regions
128
14.2
Growth and development in plants
Conditions for seed
germination ii) Warmth
allows enzymes to
work effectively
129
14.2
Growth and development in plants
Conditions for seed
germination iii) Oxygen
necessary for
respiration to provide
energy for growth
130
Two centres of activity in
seed germination
131
14.2
Growth and development in plants
Regions of growth and
development
growth only happens in
meristems (分生組織)
a group of
undifferentiated cells
132
14.2
Growth and development in plants
Regions of growth and
development
growth only happens in apical meristem
meristems (分生組織)
lateral meristem
able to divide by mitotic
cell division throughout
the plant’s life
133
14.2
Growth and development in plants
Regions of growth and
development
shoot tip
apical meristem
• tips of roots and
shoots
• increase in
length
• primary growth
(初生生長)
root tip
134
14.2
Growth and development in plants
Regions of growth and
development
lateral meristem
• periphery of
stems and roots
• increase in
thickness
• secondary growth
(次生生長)
135
14.2
Growth and development in plants
At the root tip
region of differentiation
(分化區)
region of elongation
(延長區)
region of cell division
(細胞分裂區)
136
14.2
Growth and development in plants
At the root tip
region of cell division
• produces new cells by
mitotic cell division
• protected by root cap
apical meristem
root cap (根冠)
137
14.2
Growth and development in plants
At the root tip
region of cell division
dense cytoplasm
(no vacuole)
nucleus
138
14.2
Growth and development in plants
At the root tip
region of elongation
• cells come from region
of cell division
• cells enlarge by taking
in water by osmosis and
forming small vacuoles
139
14.2
Growth and development in plants
At the root tip
region of elongation
small vacuole
thin cell wall
140
14.2
Growth and development in plants
At the root tip
region of differentiation
• small vacuoles fuse to
form large vacuoles
• cellulose fibres are made
and added to cell walls
141
14.2
Growth and development in plants
At the root tip
region of differentiation
• cell walls become thicker
and more rigid
• cells differentiate to
perform specific functions
142
14.2
Growth and development in plants
At the root tip
region of differentiation
old root hair
young root hair
xylem
larger vacuole
thicker cell wall
143
14.2
Growth and development in plants
At the root tip
144
14.2
Growth and development in plants
Increase in length
of root tip is mainly
due to increase in
number of cells.
145
14.2
Growth and development in plants
It is mainly due to
elongation of cells.
146
14.2
Growth and development in plants
At the shoot tip
young
leaf
apical meristem
region of cell division
region of elongation
region of
differentiation
147
14.2
Growth and development in plants
At the shoot tip
148
14.2
Growth and development in plants
At the periphery of stems and
roots
lateral meristem
• found between
xylem and phloem
in woody plants
• new cells differentiate
into secondary xylem
and phloem
149
lateral meristem (cambium)between xylem
and phloem
150
14.2
Growth and development in plants
At the periphery of stems and
roots
lateral meristem
epidermis
primary xylem
primary phloem
cortex
direction of growth
151
lateral meristem form a ring of dividing tissue at
the periphery of a stem
lateral meristem
152
14.2
Growth and development in plants
At the periphery of stems and
roots
increase in thickness
153
14.2
Growth and development in plants
At the periphery of stems and
roots
increase in thickness
secondary xylem
(次生木質部)
• pushed inwards
and becomes wood
secondary phloem
(次生韌皮部)
154
14.2
Growth and development in plants
At the periphery of stems and
annual ring (年輪)
roots
years later …
155
First year secondary growth
156
Spring wood and autumn wood
157
158
Primary
&
Secondary
growth
in a
woody stem
159
A Lenticel on bark
160
14.2
Growth and development in plants
1 Major processes in seed germination:
• Seed absorbs water and swells.
Stored food in the cotyledons
is converted to soluble form for
the growth of the plumule and
radicle.
161
14.2
Growth and development in plants
1 Major processes in seed germination:
• Root
Roothairs
hairs develop from the
radicle. They absorb water and
minerals from the soil.
162
14.2
Growth and development in plants
1 Major processes in seed germination:
• The hypocotyl grows out of
the soil. The cotyledons
become green and carry out
photosynthesis.
163
14.2
Growth and development in plants
1 Major processes in seed germination:
• The plumule forms young
leaves to make food.
164
14.2
2
Growth and development in plants
Water , warmth and oxygen
are needed for seeds to germinate.
165
14.2
Growth and development in plants
3 Growth occurs in
apical meristem
at the tips of roots and shoots and
lateral
lateral meristem at the periphery
of stems and roots.
166
14.2
Growth and development in plants
4 Primary growth increases the
length
length of a plant while secondary
growth increases the thickness
of the stems and roots.
167
14.2
Growth and development in plants
5a Cells in region of cell division
divide by mitotic cell division
to produce new cells.
168
14.2
Growth and development in plants
5b Cells in region of elongation
enlarge
enlarge by taking in water.
169
14.2
Growth and development in plants
5c Cells in region of differentiation
specialize to perform particular
functions
functions .
170
1
What process does the single plant
cell undergo to form a mass of cells?
A single plant cell divides repeatedly
by mitotic cell division to form a mass
of cells.
171
2
How do the unspecialized cells give
rise to a whole plant?
Through cell division, cell enlargement
and cell differentiation, the unspecialized
cells develop into a whole plant with
specialized organs like leaves, stems
and roots.
172
Growth
Development
irreversible
increase in
irreversible
increase in
size or dry mass
resulted
from
cell division
complexity
resulted from
cell differentiation
cell enlargement
173
Growth
can be measured by
the change in
size
fresh
mass
dry
mass
174
Growth
Development
in plants
start
from
whole body
germination
root
tip
in humans
occur in
shoot
tip
occur in
periphery of
stems & roots
175