Question

Assertion: Intrafascicular cambium is primary lateral meristem. Reason: It is found in lateral side of plant main axis and derived from meristem of embryo.

Short answer

Both the assertion and the reason are true, but the reason is not the correct explanation for the assertion.

Step-by-step solution

Validate Assertion

The intrafascicular cambium is a type of cambium that occurs within the vascular bundles. It is indeed a primary lateral meristem since it plays a key role in secondary growth. Therefore, the assertion is true.

Validate Reason

The reason statement defines meristematic cells as the origin of intrafascicular cambium stating that it is found on the lateral side of the plant's primary axis. This is partially true - the meristematic cells are the source of the intrafascicular cambium. However, the lateral position is not exclusive to it and can include both on the plant's lateral and longitudinal sides.

Correlate Assertion and Reason

Although the reason does not wholly describe the location of the intrafascicular cambium, it aligns with the assertion that intrafascicular cambium is a primary lateral meristem. However, the reason is not a direct explanation for the assertion, thus they are somewhat related but the reason does not explain the assertion fully.

Key concepts

Primary Lateral Meristem

The primary lateral meristem is a type of meristematic tissue responsible for the formation of certain types of vascular tissues in plants. These tissues are essential for the plant's ability to grow in thickness, a process known as secondary growth. The primary lateral meristem, including the intrafascicular cambium, is crucial because it initiates the development of this cambial activity by producing cells that will become part of the plant's vascular system.
Some common characteristics of the primary lateral meristem include:

• Location within the plant, typically found in the vascular bundles.
• Comprising of undifferentiated cells that continue to divide and contribute to plant growth.

The primary lateral meristem is also significant because it enhances plant stability. As plants grow taller, increasing their girth helps support the upper parts of the plant where leaves and branches are located. This tissue ultimately ensures that the plant can continue to survive and thrive as it ages. Its ability to adapt by growing laterally is crucial for woody plants like trees, where stability and nutrient transport efficiency are paramount.

Secondary Growth

Secondary growth refers to the process by which plants increase in thickness or girth. This growth is primarily due to the activity of lateral meristems, such as the vascular cambium and cork cambium, which include the intrafascicular cambium. It marks a significant evolutionary advantage for plants, particularly in long-lived species like trees.
Several key aspects of secondary growth include:

• Enhancing the plant's ability to transport water and nutrients by expanding the vascular system.
• Providing additional support and structure, making plants more resilient to environmental challenges.

Secondary growth is quite distinct from primary growth, which involves elongation of the plant. While primary growth occurs at the tips of roots and shoots, secondary growth happens as the plant creates more vascular tissue and a more robust outer covering. This support becomes especially important for woody plants, allowing them to grow taller and expand their canopy to capture more sunlight for photosynthesis.

Meristematic Cells

Meristematic cells are the powerhouse of a plant's growth processes. Found in regions of the plant that can continuously divide, these cells are responsible for both primary and secondary growth. A unique feature of these cells is their ability to remain undifferentiated, which allows them to give rise to various specialized cells that form the plant's organs and tissues.
Key features of meristematic cells include:

• Small size and thin walls, making them efficient in division and expansion.
• Dense cytoplasm and large nuclei, which are indicative of their active role in cell division.
• Lack of vacuoles, permitting more space for mitotic activities.

These cells can be found in different parts of the plant, structured into different types of meristems, such as apical meristems, which aid in primary growth, and lateral meristems, like the intrafascicular cambium, responsible for secondary growth. The adaptability and versatility of meristematic cells are vital for the survival and vertical and lateral growth of plants, supporting resilience and adaptation in various environments.