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Growth and development__ar
1.
2. What is Growth ?What is Growth ?
• a permanent increase in size, weight & complexity
of an organism
• Irreversible and permanent process
• involves Cell Division (Mitosis) & Cell Enlargement
3. Growth can :
• Increase the number of cells
(mitosis process)
• Increase the size of organism
• Cell differentiation and
specialization of organism
4. What is Mitosis ?What is Mitosis ?
• Mitosis occurs when…
– cell divides during growth
– an organism reproduces asexually
– repairing a damage part of body
• 2 daughter cells have exactly the same
number & kinds of chromosomes as the parent
cell
• significance: keep the number of
chromosomes constant after cell division
6. Chromatin threads condense to form
distinct chromosomes. The chromosomes
become shorter & thicker - each seems to
consist of two identical chromatids
Stage of MitosisStage of Mitosis
7. Chromosomes line up in the middle part
(equatorial region) of the cell
Stage of MitosisStage of Mitosis
8. Two chromatids of each
chromosome separate & move to
opposite poles of the cell
Stage of MitosisStage of Mitosis
9. The chromatids become chromosomes
of the two daughter cells
Stage of MitosisStage of Mitosis
10. How to Measure Growth ?How to Measure Growth ?
• by height / length
– defect : do not take into account the growth
in other dimensions
• by fresh mass
- the mass of living organism without removing water
from the body
- easy and convenient method
- no need to kill the organism
- Disadvantage ?????
11. • by dry mass
– The mass of organism after all water has
been removed from the body by heat
– An accurate measurement of growth
– defect : too destructive (the organisms die)
– defect : too time consuming
16. Animal GrowthAnimal Growth
• Mitosis process occur – to increase
the number & size of cells
• different parts have different growth
rate
• eg. the brain grows first in baby
• eg. the reproductive system grows
only at puberty
22. 3. Slow growth
- Growth rate is slow
- Cells have reached maturity
- Growth rate is limited by external factors (food
storage) & internal factors (hormone)
4. Stationary
- Growth rate is zero
- Cell division occur to replace dead or damaged
cells only
- Rate of cell division is equal to the rate of cell
mortality
23. 5. Senescence / negative growth phase
- Growth rate is negative because of aging &
eventually die
- Lack of growth hormone
30. Essay Q : page 27
• P: Graph shows continuous growth pattern/ sigmoid curve
Stage A
• F1: Growth rate decrease
• E1: The mass decreases when endosperm is used for
growth
Stage B
• F2: Growth rate increases gradually
• E2: new cells are produced until it reach maximum point
31. Stage C
• F3: Maximum growth rate is achieved/
matured
• E3: Cells involve in division decrease and
undergo differentiation
Stage D
• F4: growth rate decrease/ ageing
• E4: loss of body mass
32.
33.
34.
35. Growth in plants
Primary growth Secondary growth
• Occur in all plants
• produce vascular
bundle (xylem &
phloem)
• to increase the length of
shoot tips & root tips
(apical meristem)
• Occur in woody plants
• produce secondary xylem,
secondary phloem, secondary
cortex & cork
• to increase diameter of stems
& trunks
36. Growth in PlantsGrowth in Plants
• Primary growth
– grow in length
• by apical meristem (the
plant tissue that retain
the ability for cell
division)
meristem
37. • First form of growth
• Takes place in the apical meristem tissues
in the apex of the shoot and the root.
• Tip of the shoot and the root are divided
into three regions
* cell division
* cell elongation
* cell differentiation
42. Zone of cell division
- occur at shoot & root tip (apical
meristem)
- Characteristics of meristematic cells :
- large nucleus
- small vacoule
- Cell division – mitosis occur to
produce new cells
- increase the number of cells
43. Zone of cell elongation
-Vacoule absorbs water to form
a large vacoule
- The Process is called
vacoulation
- The cell become enlarge &
elongate
- Characteristics of cells :
- large vacoule
- small nucleus
44. Zone of cell differentiation
-The cells differentiate into a specialised
cell for carrying out specific function
- Example : xylem & phloem
46. Secondary growthSecondary growth
• Secondary growth
– grow in diameter
(only in dicotyledonous
plants)
– by cambium
to produce secondary xylem
and secondary phloem
which forms annual ring
– cork cambium : to form cork layer
to replace the broken epidermis
(6-yrs)
50. Secondary growth
- Vascular cambium divide laterally joins to form a
complete cambium ring
Cambium
ring
phloem
xylem
Vascular
cambium
epidermis
cortex
51. -vascular cambium divide tangentially to form
secondary xylem in the inner layer & secondary
phloem are formed in the outer layer
- the primary xylem will be pushed towards the pith
- the primary phloem will be pushed towards the
epidermis
52.
53. • cork cambium divide actively by mitosis
to form secondary cortex towards the
vascular bundle and form the outer cork
towards the epidermis
• The division process by the vascular
cambium and cork cambium occurs
repeatedly and continuously
• The division cause the increase of the
diameter of stem
• The division cell process is called cell
mitosis
64. Structure q no.5
a) 2 differences of the growth curve of rat &
grasshopper
i. The shape of growth curve of rat is sigmoid
but the shape of growth curve of g/h is step
shape/staircase
ii. The growth curve of rat shows continuous
growth but the growth curve of g/h shows
discontinuous growth
67. Do all parts of the radicle grow during the experiment ?
Ans: No. Growth occurs only in the region behind the
tip.
pin cork
cotton
wool
cork
beaker
strip of
filter paper
water
radicle marked
at 1mm intervals
68. Where is the region of maximum growth in the root ?
Ans: The region of elongation which is located
immediately behind the tip.
pin cork
cotton
wool
cork
beaker
strip of
filter paper
water
radicle marked
at 1mm intervals
69. Growth Patterns in PlantsGrowth Patterns in Plants
dry
mass
time
annual plant
