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 as 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 bodies. 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 is infinite.
In the biological context, there is a tiny variation between both the terms- growth, and development. These are the terms and phrases which are used for the identification of a series of events in the lifetime of an organism or a plant.
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 as 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.
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 the 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 the flowering, which includes the formation and development of its roots, leaves, and stem, is termed as vegetative growth.
Reproductive Growth: plants reproduce through flowers. So, the stage at which plants begin to flower, that growth is termed as reproductive 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 as 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.
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 become enlarged in this stage.
This is the last stage. The cells adopt a specific shape and size according to their functions.
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.
Question 1) Explain the Internal and External Factors Affecting the Growth?
The external factors affecting growth and development are:
Light – Plants do photosynthesis to transform the energy obtained from light into chemical energy, which can then be utilized to carry out other activities.
Temperature – An optimum temperature is very important for every organism in order to live, grow, and reproduce. It can vary from organism to organism.
Water – water is another important element for plants. It is absorbed through the soil by the roots and is used in the procedure of carrying out photosynthesis and various other biochemical processes inside the plant body.
Minerals and Other Nutrients – Organisms require various minerals and nutrients to support their biochemical processes and metabolism. This will, in the end, help them boost their growth process.
The internal factors affecting growth and development are:
The internal factors which aid biological growth and development in plants contain hormones that are also known as plant growth regulators. They include names like Auxins, Gibberellins, Cytokinin, Ethylene, Abscisic acid. For the human growth and development, a hormone known as Somatotropin is responsible.
Question 2) When it Comes to Flowering Plants, there are Different Parameters and not a Single Parameter Used to Demonstrate its Growth and Development. Why is that so?
Answer The organs of a flowering plant such as stem, leaves, roots, fruits, flowers, etc. develop differently at their own pace in various stages throughout the lifespan of a flowering plant. These plant organs require specific variables to display their development. For fruits, corms, etc. weight is used as a parameter to indicate their growth. For leaves, the surface area is used to indicate growth. For stems and roots, length and girth are used as a parameter. Hence, there is more than one parameter to demonstrate the growth of flowering plants.