Problem 13 - Objective Biology for NEET

Question

The unique ability to retain the capacity of growth in plants is due to the presence of (a) Lifetime differentiation (b) Activator hormones (c) Chlorophyll to utilize energy lifetime (d) Meristems at certain locations

Step-by-Step Solution

Answer

The correct answer is (d) Meristems at certain locations.

Step 1: Analyzing options

Start by analyzing each option. Lifetime differentiation refers to the development of specific traits in a plant over its lifespan. Activator hormones are substances that promote growth and development in plants. The chlorophyll's responsibility is to harness energy from sunlight during photosynthesis, while meristems are specific regions in plants where cells are actively dividing and promoting growth.

Step 2: Understanding plant growth

The understanding of plant growth suggests that the ability to grow continuously is due to cell division occurring in certain areas, called meristematic regions. These are regions in plants where cells are actively dividing and promoting growth.

Step 3: Select the correct answer

Based on the analysis in step 1 and step 2, the most probable answer is option (d) Meristems at certain locations. Meristematic cells have the unique ability to continue dividing throughout the life of the plant, making them responsible for the plant’s continuous growth.

Key Concepts

Meristems

Plants have special regions called meristems, which are crucial for their growth. Meristems are like growth factories. They are found in parts of the plant where growth continuously occurs. These include areas like the tips of roots and shoots. These regions contain meristematic cells, which are small, with thin walls and a dense cytoplasm. Their unique feature is the ability to divide continuously.
Meristems are responsible for the plant's ability to grow throughout its life. They work by generating new cells, which can then grow and differentiate into various types of plant tissues. Without meristems, plants wouldn't be able to increase in size or produce new leaves and flowers. This is why meristems are sometimes referred to as a plant’s "growth engine."

• Located at root and shoot tips, as well as in other specific regions
• Contain cells that can divide and differentiate
• Essential for height and root system development

Cell Division

Cell division is a fundamental process in plant growth. When we talk about cell division in plants, we're usually referring to mitosis, which is a method of making identical copies of cells. Mitosis happens in the meristematic regions, allowing plants to grow taller and roots to grow deeper.
The process of cell division isn't just about multiplying cells; it's also about creating the right kind of cells. After division, these new cells can differentiate and become part of the plant's tissue. This differentiation is crucial because it leads to the formation of structures like leaves and stems. Proper cell division is essential for a plant’s overall health and structure.

• Occurs in meristematic regions, enabling growth
• Leads to differentiation and specialization of cells
• Supports the growth of new plant tissues and structures

Activator Hormones

Activator hormones in plants play a significant role in promoting growth and development. These hormones act like signals, helping the plant know when to grow. They don't cause growth directly but instead influence how and where growth should happen.
Common activator hormones include auxins, gibberellins, and cytokinins. Each of these hormones play specific roles: - **Auxins**: Encourage growth towards light by elongating cells. - **Gibberellins**: Help in stem elongation and seed germination. - **Cytokinins**: Promote cell division, ensuring cells multiply effectively. Together, these hormones form a network, guiding the plant's response to its environment. They ensure that growth happens efficiently and at the right times, making them essential for a plant's adaptability and survival. These activator hormones work closely with meristematic regions to ensure a well-coordinated growth process.

• Influence growth directions and patterns
• Include auxins, gibberellins, and cytokinins
• Essential for adapting growth according to environmental cues