2. Limited (annual plants) Unlimited (perennial plants)
Chapter review…
Growth
Growth phases
Growth rate
Growth measurement
Absolute growth curve
Absolute growth rate curve
Definition
Phases of growth
Cell division
Cell enlargement
Cell differentiation
Wet/fresh mass
Dry mass
Growth curve
sigmoid
human
Limited (annual plants)
intermittent
Unlimited (perennial plants)
Growth under extreme condition
Seed dormancy
Aestivation
hibernation
Diapause

3. Growth Phases By the end of the lesson the students should be able to:
Objectives 1
By the end of the lesson the students should be able to:
(i) define the term growth
(ii) name the three phases of growth
(iii) describe the three phases of growth

4. Growth Phases
Introduction 2
A series of changes in the life of an organism –from zygote to adult – involves two major processes:
(i) Growth
(ii) Development

5. Growth Phases
Definition of Growth 3
Any irreversible and permanent increase in quantitative parameters that can be measured such as:
length
height
size
volume
number
of cells
cytoplasmic
mass
dry
mass
surface
area

6. Growth Phases Any qualitative change and involve cell differentiation:
Definition of Development 4
Any qualitative change and involve cell differentiation:
shape
specificity
complexity

7. Growth Phases Growth in Unicellular Organisms cytoplasmic mass size5
is controlled by the size of its cytoplasm that is controlled by its nucleus
when achieve a certain size, it divides to produce 2 daughter cells of smaller size
cell division is followed by the growth of 2 daughter cells until achieve the size of mature unicellular organism

8. Growth Phases Growth in Unicellular Organisms6
differentiation is very limited in unicellular
organism
reproduce asexually through binary
fission for population growth to take place

9. produce new daughter cells of smaller size
22.1 Growth Phases
Growth in Unicellular Organisms 7
1. Repeated divisions
produce new daughter cells
of smaller size
2. Limited growth
i.e. equals to those of parent cells’
also limited differentiation

10. Physical characteristic
Growth Phases
Growth in Multicellular Organisms 8
Size of organism
Increase in
Changes in
Appearance
height
Weight
Develop the complexity and function of the organism
Physical characteristic
Number of cells

11. Growth Phases Three phases: 3. Cell differentiation
Growth in Multicellular Organisms 8
Three phases:
3. Cell differentiation
2. Cell enlargement
1. Cell divisions

12. Growth Phases The basic process in growth
1. Cell Division 9
The basic process in growth
mitotic cell division in all somatic cells
Through mitosis, the number of cells increase

13. Growth Phases
1. Cell Division 10
Gave the living world an opportunity to increase the size of the organisms
Rate of division depends on the cell types, the species and other conditions – physical, chemical

14. the increase in the cell size and volume
Growth Phases
2. Cell Enlargement 11
the increase in the cell size and volume
increase in the cytoplasmic content,
e.g. number of organelles

15. Growth Phases 2. Cell Enlargement12
Plants - cells grow by adding organic material to their cytoplasm, or
- addition of water, into the large central vacuole, accounts for 90% of plant cell’s expansion

16. Growth Phases 2. Cell Enlargement13
Animals - cells grow by synthesizing a protein- rich cytoplasm,
a metabolically expensive process

17. each cell grows to the limit
Growth Phases
2. Cell Enlargement 14
each cell grows to the limit
the ability of the cell nucleus to support the increase in cytoplasmic volume
the cell divides before it reaches the limit

18. the cell undergoes change in form
Growth Phases
3. Cell Differentiation 15
the cell undergoes change in form
in order to perform specialized functions - same set of genetic information to produce a diversity of cell types

19. Growth Phases 3. Cell Differentiation16
the adult cell divides repeatedly
resulting in a group of cells
the cells start to differentiate from each other in its structure and chemical composition

20. Growth Phases 3. Cell Differentiation e.g. 1: red blood cells17
e.g. 1: red blood cells
in embryonic stages, in the cells destined
to be the blood tissue
there’s an increase in the amount of
hemoglobin molecules and carbonic
anhydrase
 disappearance of nucleus
 enhance the ability for transportation of O2 and CO2

21. Growth Phases 3. Cell Differentiation18
e.g. 2: meristematic vascular cells
the meristematic cells differentiate into:
 xylem: transportation of water and minerals
 phloem: transportation of products of photosynthesis and hormones

22. 2 major factors of growth: extrinsic and intrinsic:
22.1 Growth Phases
Influential Factors 19
2 major factors of growth: extrinsic and intrinsic:
extrinsic factors
in plants:
light intensity, duration of light period, temperature, humidity, water, soil and minerals
in animals: nutrients, oxygen

23. intrinsic factors Influential Factors
22.1 Growth Phases
Influential Factors 20
intrinsic factors
 in plants: plant phytohormones e.g. auxins, gibberillins, cytokinins
 in animals: hormone secretions of glands e.g. hypothalamus, pituitary, thyroid, gonads – promote or inhibit growth in animals

25. Measuring Growth Objectives1
By the end of the lesson the students should be able to:
(i) describe the methods in measuring growth
(ii) define the terms dry mass and wet mass
(iii) describe the advantages and the disadvantages of measuring dry mass and wet mass of the
given specimens

26. Measuring Growth 2
Growth involves the increasing of protoplasm of an organism.
Growth can be estimated by measuring a particular parameter over a specific time.
The best parameter and commonly used to measure growth are:-
- Biomass ( dry or fresh )
- Length
- Width
- Size
Height
- Volume
- Number
- Surface Area 26

27. Measuring Growth Periodic linear measurement
Estimate length/ height 3
Periodic linear measurement
Eg: Measuring height for human being – the best way to measure the growth of an individual 27

28. Measuring Growth Periodic linear measurement - Plant
Estimate length/ height 3
Periodic linear measurement - Plant
height is not a suitable parameter
the growth is measure by the length of branches, size of leave leaves, root and the food storage structures underneath the ground.
Auxanometer
Measure Length of stem 28

29. Measuring Growth Surface Area /11
Surface area of a leave can be determine by draw the outline of the leave at a graph paper or square paper (1cm x 1cm) and count the square inside the leave outline
What is the surface are for the leave?
20 cm2 / 29

30. Measuring Growth 4
the more appropriate parameters for the measurement of growth in multicellular organisms are the weight or mass
wet mass/weight
dry mass/weight

31. Measuring Growth Wet Mass5
the mass of the organism in the normal condition
The advantages
easier and convenient to measure
no need to destroy the specimen
the same organism can be used for repeated
measurement

32. Measuring Growth Wet Mass inaccurate and inconsistent6
The disadvantages
inaccurate and inconsistent
because it is affected by the fluctuation of
the amount of water in the organism
( water ~ % wet mass )
shows greater variation due to the environment
or the organism behavior

33. Measuring Growth the mass of the organism after its water
Dry Mass: Definition 7
the mass of the organism after its water
content is fully eliminated
it implies the actual growth of the organism
the actual growth is the change/increase in the amount of other substances, apart from water

34. Measuring Growth Dry Mass: Methods 1. The specimen is destroyed…8
1. The specimen is destroyed…
2. …then transferred into the oven at 110°C to eliminate its water content.
3. Next, it is put inside a desiccator to
ensure the water is completely eliminated.
4. The dried specimen is weighed.
5. The above procedures are repeated until a constant value is obtained.

35. Measuring Growth Dry Mass The advantages more accurate9
The advantages
more accurate
the amount of water in an organism is not
constant, i.e. depends on the water intake
by the individual organism

36. Measuring Growth Dry Mass destruction of specimens10
The disadvantages
destruction of specimens
in repeated measurement, specimens of the
similar age, size are required (destroyed!) to
avoid or minimize errors in the measurement
Large samples of genetically identical organism
need to be grown under similar condition
Time consuming