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

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

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

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

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

Growth Phases Growth in Unicellular Organisms cytoplasmic mass size 5 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

Growth Phases Growth in Unicellular Organisms 6 differentiation is very limited in unicellular organism reproduce asexually through binary fission for population growth to take place

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

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

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

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

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

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

Growth Phases 2. Cell Enlargement 12 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

Growth Phases 2. Cell Enlargement 13 Animals - cells grow by synthesizing a protein- rich cytoplasm, a metabolically expensive process

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

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

Growth Phases 3. Cell Differentiation 16 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

Growth Phases 3. Cell Differentiation e.g. 1: red blood cells 17 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

Growth Phases 3. Cell Differentiation 18 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

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

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

Measuring Growth Objectives 1 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

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

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

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

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

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

Measuring Growth Wet Mass 5 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

Measuring Growth Wet Mass inaccurate and inconsistent 6 The disadvantages inaccurate and inconsistent because it is affected by the fluctuation of the amount of water in the organism ( water ~ 70 - 90% wet mass ) shows greater variation due to the environment or the organism behavior

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

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.

Measuring Growth Dry Mass The advantages more accurate 9 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

Measuring Growth Dry Mass destruction of specimens 10 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