Question

Which of the following is not the characteristic of the cells in elongation phase? (a) Cell enlargement (b) New cell wall deposition (c) Decrease in volume (d) Both (a) and (b)

Short answer

(c) Decrease in volume

Step-by-step solution

Process of Elimination

Review the characteristics associated with the elongation phase in cells, and cross-reference each option. \n(a) Cell enlargement: this is often observed in the elongation phase, so this option is incorrect. \n(b) New cell wall deposition: also a characteristic of the elongation phase, so this is also incorrect.\n(c) Decrease in volume: this is contrary to the general idea of elongation, wherein cells usually increase in volume, not decrease. Therefore, the best answer to the question 'Which of the following is not the characteristic of the cells in elongation phase?' is (c).\n(d) Both (a) and (b): As both (a) and (b) are characteristics of the elongation phase, this option is incorrect.

Final Answer

The correct answer is (c), a decrease in volume, as it contradicts what happens in the elongation phase of cell growth. Volume typically increases, not the opposite, which makes (c) the best response.

Key concepts

Cell Growth Phases

The cell growth process is an essential part of plant development and involves several distinct stages. Each phase plays a vital role in ensuring the proper formation and function of the plant. In simple terms, growth phases ensure that the cell proceeds in an ordered manner from its birth to its eventual specialized function in the plant.

There are typically three primary phases of cell growth:

• Cell Division: This is where new cells are generated through the process of mitosis, resulting in a group of cells ready to grow and differentiate.
• Cell Elongation: Occurs after the division phase. During this stage, cells increase in size significantly, mainly in one direction. It's a dynamic process characterized by cell enlargement and new cell wall deposition.
• Cell Differentiation: The final phase where cells become specialized to perform specific functions in the plant. These specialized cells contribute to the formation of plant tissues and organs.

Cell growth phases ensure each plant cell performs efficiently, contributing collectively to the plant's overall growth and health.

Cell Enlargement

Cell enlargement is a crucial step within the growth process and primarily occurs during the elongation phase. In this stage, the cells grow vastly in size, often becoming several times their initial volume. This increase is essential as it aids in developing the plant's structure, allowing it to grow taller and more robust.

Key factors influencing cell enlargement include:

• Water Uptake: Water plays a significant role in cell enlargement by entering the vacuole, an internal plant cell structure, and generating turgor pressure. This pressure causes the cell to expand.
• Hormones: Plant hormones such as auxins stimulate cell elongation by altering the cell wall's properties, making it more flexible and able to stretch.
• Nutrient Supply: Adequate availability of nutrients supports various metabolic activities that power the growth process.

Cell enlargement is fundamental for plant height and girth, essentially giving plants the ability to compete for sunlight and optimize photosynthesis.

Cell Wall Deposition

Cell wall deposition is a companion process to elongation, playing a vital role in maintaining cell integrity as it enlarges. The cell wall acts like an outer shell providing structural support and protection to plant cells.

Here are some important aspects of cell wall deposition:

• Cell Wall Composition: The primary components include cellulose, hemicellulose, and pectin, which together form a strong yet flexible barrier. This barrier enables cells to maintain shape while expanding.
• Process of Deposition: After water uptake aids in the enlargement of the cell, new cell wall materials are synthesized and deposited along the stretching cell walls.
• Flexible and Rigid Components: While initial deposition involves more pliable components, secondary deposition—involving lignin—occurs when cells reach their final size, providing additional strength.

Overall, cell wall deposition ensures the structural integrity of the plant is maintained, which is crucial for withstanding environmental stress and preventing cellular damage during growth.