Growth and Development

Growth It is a process involving cell division and cell enlargement. Cell divisions (Mitosis or Meiosis) is process which leads to an increase in cell number. Cells are usually small and unspecialized after cell division. Cell enlargement is a kind of process which leads to an increase in the volume of individual cells.

Different Ways to Measure Growth - Dry Mass Dry mass : Place in oven at a temperature slightly over 100 o C until its mass become constant. Advantage : Most accurate and commonly used in plant.

Different Ways to Measure Growth - Dry Mass II Disadvantage : The organism will be killed. Growth of the same organism cannot be measured continuously and large number of organisms are needed. Finally, time consuming.

Different Ways to Measure Growth - Fresh Mass Fresh Mass : Take the mass of the organism under normal conditions. Advantage : Easy to measure and no need to kill the organism. Disadvantage : Less accurate and changes in the water content of an organism are not related to growth.

Different Ways to Measure Growth - Size Size : Measure the organism in different parameter such as length, height, surface area and volume. Advantage : Easy, quick and no need to kill the organism. Disadvantage : Not accurate enough because can measure in only one dimensions and measurement cannot truly represent its growth.

Development Development means the series of orderly changes that occur in the body structure and organization (or qualitative changes) of an organism. Starting from the zygotic stage until maturity. Often lead to an increase in the complexity of the organism.

Process Leading to Development Mainly by cell specialization or cell differentiation. Lead to changes in their shapes and structures of cells, so they can adapt to certain functions Cells will lost their further division ability after development

Complexity - The Level of Organization

Complexity - The Level of Organization II Cells  Tissues  Organs  Systems  Organism Cells differentiate into different cell types and similar cells integrate into tissue which can perform one or more function(s) Combination of different tissues form organ, which function as a unit.

Complexity - The Level of Organization III Systems are organized by different type of organs, which carry out a set of functions in a co-ordinate way to ensure that the organism works as an integrated whole.

Growth and Development in Animals Cells are grown by repeated mitotic divisions. These processes generate complexity, which start from zygote to embryo and then the foetus with tissues organs and finally, systems developed before birth.

Growth and Development in Animals II growth curve of human five stages –fast grown in first three-years of life and during adolescence –the other stages are relatively slow growth

Growth and Development in Animals III If the bodies of a man at different ages are drawn to the same length, and then the proportion of different body parts is compared, it can be seen that different parts of the body grow at different rates.

Growth and Development in Plants Root tip is the site for growth and development of the root of plants.

Three Region of Root Tip Region of Cell Division: –contain actively-dividing cells –new cells are produced continuously by mitosis. Region of Elongation: –the region of maximum growth in root –young cells enlarge rapidly here mainly by an increase in length which involved cell elongation.

Three Region of Root Tip II Region of Differentiation: –cells undergo cell specialization (or cell differentiation), i.e. they change their shapes and structures to become specialized in different functions. –As a result, different tissues (e.g. xylem, phloem, epidermis with root hairs) start to appear in this region.

Growth Curve in Plant 1) Dry mass decreases during early stage of germination because respiration of food reserves in the seedling 2) Dry mass increases because leaves are producing food by photosynthesis 3) Dry mass decreases due to deposal of seeds or fruits

Growth and development at the shoot tip Growth in shoots is similar to roots. There also have 3 regions: region of cell division, region of elongation and region of differentiation.