Stages and Factors Influencing Organism Growth
Growth can be explained as an irreversible continual increase in the size of a part of the body or even of a single cell. In other words, growth is considered the most fundamental attribute of any living organism. It is also accompanied by several metabolic processes taking place at the cost of energy in the body. The systems can be one of the two types, either anabolic or catabolic.
When we look at the context of growth in plants, we observe that the seeds germinate and then grow into seedlings, which subsequently develop into the structure or form of an adult plant or a tree. These are the different stages of growth and development of plants, which are infinite.
In the biological context, there is a tiny variation between both the terms growth and development. These are the terms and phrases that are used for the identification of a series of events in the lifetime of an organism or a plant.
Definition of Growth and Development in Organisms
Growth refers to an increase in the organism's/plant's body size and mass with time. whereas, when an organism or a plant grows mentally, physically, as well as physiologically, the processor of that phase is recognized and named as the development of that organism/plant.
Growth happens over the lifespan of an organism, but not consistently. It happens at a faster rate until the animals and plants have matured or attained maturity. After that stage, the growth slows down steadily and stops beyond a certain time.
The process of development is the one in which an organism or a plant experiences full mental growth and maturity. The organism develops mentally, physiologically, and physically during this phase. The process in which the shape and structure of an organism get developed is termed morphogenesis. And, the process in which there are significant changes in the internal and external organs, tissues, and cells of the body of an organism is known as differentiation.
Types of Growth in Organisms
Primary Growth: This growth happens as a result of the mitotic divisions. It happens in the meristematic cells, which are located at the roots and shoots of a plant. As a result, it leads to an extension in the length of the plant. This is known as primary growth.
Secondary Growth: The secondary meristem, which leads to an increase in the plant diameter recognized as secondary growth.
Vegetative Growth: The growth of a plant before flowering, which includes the formation and development of its roots, leaves, and stem, is termed vegetative growth.
Reproductive Growth: plants reproduce through flowers. So, the stage at which plants begin to flower, that growth is termed reproductive growth.
Basic Characteristics of Growth
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The Formative Phase
The most important and mandatory process in the growth of any plant is the division of cells. Every new cell is formed as a result of the division of the previous cells. A kind of cell division that involves both qualitative and quantitative division of cells and occurs during the growth of a plant is termed mitosis.
This process takes place in two steps:
Karyokinesis: the division of the nucleus
Cytokinesis: the division of the cytoplasm
A large number of cells carry out this process in higher plants at the meristematic location.
Some daughter cells retain this while some enter the next stage of growth, known as the cell enlargement.
Cell Enlargement
This stage of cell enlargement and cell differentiation involves the formation of protoplasm, vacuoles, hydration, and cell wall. The cell wall is then made thicker and permanent. The size of organs and tissues becomes enlarged in this stage.
Cell Maturation
This is the last stage. The cells adopt a specific shape and size according to their functions.
Factors Affecting the Growth and Development in Organisms
Hormones in animals and growth regulators help plants grow at a steady pace. Some of the factors which influence the growth of different living organisms can be divided into two distinct categories, which include internal and external factors. Internal factors include heredity, enzymes, and hormones. while the external factors include light, water, temperature, and minerals or nutrients.
Conclusion
Growth and development are essential attributes of a living organism. They may have different definitions based on the context, but in a general way of understanding, growth refers to anything that is increasing in numbers, size, mass, etc. whereas development is defined as the continuous growth of living organisms over a course of time in their life span. Development is also associated with maturity and acquiring various skills by organisms, which not only shows that they are actually growing but also proves their successional development as well.
FAQs on Growth and Development of Organism Explained
1. What is the main difference between growth and development in biology?
The primary difference lies in their nature. Growth is a quantitative process, referring to the permanent and irreversible increase in the size, mass, or volume of an organism or its parts, primarily through cell division and enlargement. For example, a plant getting taller. Development, on the other hand, is a qualitative process that includes all the changes an organism undergoes throughout its life cycle, from germination or birth to maturity and death. It encompasses growth, differentiation (cells specialising for functions), and maturation. Essentially, growth is a part of development.
2. What are the key characteristics that define growth in living organisms?
Growth in living organisms is defined by several key characteristics:
Increase in Mass and Size: This is the most visible sign of growth, as organisms accumulate more protoplasm.
Cell Division: Growth is fundamentally driven by the process of mitosis, where cells replicate to increase their number.
Cell Enlargement: Following division, individual cells increase in size, contributing to overall growth.
Irreversibility: True growth is a permanent increase; an organism does not shrink back to its original size under normal conditions.
It is an Anabolic Process: Growth involves metabolic processes that build up complex molecules from simpler ones, consuming energy.
3. What are the major internal and external factors that influence an organism's growth?
An organism's growth is regulated by a combination of internal and external factors.
External Factors include environmental conditions such as:
Light: Essential for photosynthesis in plants, which provides the energy for growth.
Temperature: Organisms have an optimal temperature range for metabolic activities that support growth.
Water and Nutrients: These are the raw materials required for building new cells and tissues.
Internal Factors are intrinsic to the organism:
Genetic Factors: The genetic makeup of an organism sets the blueprint and limits for its potential growth.
Hormones: In plants, hormones like auxins, gibberellins, and cytokinins promote growth, while in animals, hormones like somatotropin (growth hormone) play a crucial role.
4. Why is growth in plants measured using different parameters like length, weight, and surface area, instead of just one?
Growth in plants is a complex process where different organs grow at different rates and in different ways. Using a single parameter would be insufficient and misleading. For example:
Length is a good parameter for measuring the growth of stems and roots.
Surface Area is more appropriate for measuring the growth of leaves, as their primary function (photosynthesis) depends on the area exposed to light.
Fresh or Dry Weight is the best parameter for measuring the growth of fruits, seeds, or storage organs, where the accumulation of biomass is the key indicator.
Therefore, multiple parameters are used to get a complete and accurate picture of the overall growth and development of the entire plant.
5. How are the processes of growth and development interconnected in an organism's life cycle?
Growth and development are two distinct but inseparable processes. Growth provides the necessary material for development to occur. For an embryo to develop complex organs like a heart or brain, it must first grow in cell number and size. Conversely, development directs growth by a process called differentiation, where cells specialise to form tissues and organs. A simple increase in cell mass (growth) without the orderly sequence of changes (development) would only result in an unorganised cellular mass, not a functional organism. Thus, development gives meaning and structure to the quantitative increases achieved through growth.
6. Can you provide some examples of growth and development in plants and animals?
Certainly. In plants, a clear example is a seed germinating into a seedling and then growing into a mature tree. This involves growth (increase in height and girth) and development (formation of roots, stem, leaves, flowers, and fruits). In animals, an example is a tadpole undergoing metamorphosis into a frog. The increase in the tadpole's size is growth, while the process of losing its tail, developing legs, and adapting to land is development. Similarly, in humans, the transition from an infant to an adult involves physical growth (increase in height and weight) and developmental changes like puberty and the acquisition of cognitive skills.
7. What are the three primary phases of growth in organisms?
The process of growth in organisms, particularly in specific regions like plant meristems, can be divided into three distinct phases:
Phase of Cell Division (Formative Phase): This occurs in meristematic regions where cells are actively dividing through mitosis. These cells are typically small with dense cytoplasm and large nuclei.
Phase of Cell Enlargement (Elongation Phase): Following division, the newly formed cells absorb water and expand, increasing in size. This phase is responsible for the rapid increase in the length or size of an organ.
Phase of Cell Maturation (Differentiation Phase): In this final phase, the enlarged cells develop into their final, specialised forms to perform specific functions, becoming part of permanent tissues like xylem, phloem, or parenchyma.
