Question

Plant shows continuous growth throughout their life because of (a) Mitosis (b) Amitosis (c) Meiosis (d) All of these

Short answer

The answer is (a) Mitosis.

Step-by-step solution

Understand the Cellular Division Processes

In biology, there are three primary types of cellular division: mitosis, meiosis and amitosis. Mitosis is a process where a single cell divides into two identical daughter cells (cell replication). Meiosis, on the other hand, is a type of cell division that reduces the number of chromosomes in the parent cell by half and produces four gamete cells. This process is required to produce egg and sperm cells for sexual reproduction. Lastly, Amitosis is a direct cell division in which, following nuclear division, there is a simple cleavage of the cell body into two parts, each of which contains a nuclear half.

Link Cellular Division Process to Plant Growth

Continuous growth refers to the fact that plants continue to grow for as long as they live, unlike humans and animals which stop growing after reaching a certain age. This continuous growth is due to the activity of 'meristems', a type of plant tissue that possesses the ability to constantly divide and produce more cells. The type of cellular division that is responsible for this continuous division and growth is mitosis.

Confirm the Answer

Reviewing this information, one can deduce that of the given options, mitosis is the cellular division process that enables continuous growth in plants.Thus, the answer is (a) Mitosis.

Key concepts

Mitosis

Mitosis is a fundamental process in plant growth. It refers to the method by which a single cell divides to produce two identical daughter cells. This division is vital for plant development, allowing growth in size and mass. During mitosis, the cell goes through several phases:

• Prophase: Chromosomes are condensed into visible structures.
• Metaphase: Chromosomes align at the center of the cell.
• Anaphase: Chromosome pairs are pulled apart to opposite ends of the cell.
• Telophase: The cell splits and two new nuclei form.

Mitosis is key in plants as it replaces old cells, repairs damaged tissues, and supports growth from meristem tissue. This ensures that plants can continually produce new cells throughout their lifespan.

Continuous Growth

Plants are unique in that they exhibit continuous growth throughout their entire lifetime. Unlike most animals, plants do not have a predetermined size or shape. This growth pattern is attributed to their ability to continuously form new cells. Continuous growth happens primarily in specific regions known as meristems located at root tips and shoot tips. These meristems are zones of actively dividing cells, facilitated by mitosis. Key factors allowing continuous growth include:

• Environment: Availability of nutrients, water, and light enhances growth.
• Hormones: Substances like auxins and gibberellins regulate expansion.
• Genetics: Inherent growth potential based on species.

By maintaining active meristems that perpetually divide, plants can grow endlessly, adapting to their surroundings for survival and reproduction.

Cell Division

Cell division is a crucial process in biology, powering both growth and reproduction. In plants, cell division is predominantly achieved through mitosis. Mitosis in plant cell division involves duplication of chromosomes and division of a mother cell into two genetically identical daughter cells. This ensures that new cells have the same number and type of chromosomes as the parent cell. Reasons cell division is vital for plants include:

• Growth: Increasing the number of cells contributes to larger plant size.
• Repair: Damaged cells are replaced to maintain plant health.
• Differentiation: Cells specialize in forming different tissues and organs.

The seamless operation of cell division is essential for a plant’s life, enabling it to grow, adapt, and reproduce efficiently.

Meristems

Meristems are specific regions in plants consisting of undifferentiated or partially differentiated cells. These regions are responsible for the indeterminate, continuous growth of plants. Meristems can be categorized into several types:

• Apical meristems: Located at the tips of roots and shoots, driving primary growth which increases length.
• Lateral meristems: Found along the sides of stems and roots, contributing to secondary growth, which increases girth.
• Intercalary meristems: Found at the bases of leaves or internodes, helping in rapid regrowth.

Meristematic cells are unique because they can divide continuously. This characteristic is essential for growth, as well as generating new tissues for repair and replacement. Understanding meristems offers insights into how plants maintain their growth and functions over time.