Problem 6 - Campbell Biology

Question

Which of the following arise(s), directly or indirectly, from meristematic activity? (A) secondary xylem (B) leaves (C) dermal tissue (D) all of the above

Step-by-Step Solution

Answer

The correct answer is (D) all of the above.

Step 1: Understand Meristematic Activity

Meristematic activity involves the regions of plants where cells are capable of continuous division and growth. These regions include apical meristems, which contribute to primary growth, and lateral meristems, which contribute to secondary growth.

Step 2: Evaluate Secondary Xylem

Secondary xylem is produced by the vascular cambium, a type of lateral meristem. Hence, secondary xylem arises from meristematic activity.

Step 3: Evaluate Leaves

Leaves develop from the apical meristems, which are located at the tips of roots and shoots. These apical meristems are responsible for the primary growth of the plant, including the formation of new leaves.

Step 4: Evaluate Dermal Tissue

Dermal tissue originates from the protoderm, which is derived from the apical meristem. Thus, dermal tissue also arises from meristematic activity.

Step 5: Conclusion

Since secondary xylem, leaves, and dermal tissue all arise directly or indirectly from meristematic activity, the correct answer is (D) all of the above.

Key Concepts

apical meristem

Apical meristems are critical for the growth of plants. These regions are found at the tips of roots and shoots. They are responsible for a type of growth known as primary growth.

This primary growth allows plants to increase in length. This is crucial for plants to reach sunlight and for roots to explore more soil for nutrients and water.

• Apical meristems are composed of undifferentiated cells that can divide and form various specialized tissues.
  
• As these cells divide, they contribute to the elongation of the plant body.
  

Importantly, leaves also develop from apical meristems. Without apical meristem activity, plants wouldn't be able to grow taller or develop new leaves, which are essential for photosynthesis. Thus, the meristematic activity occurring in apical meristems supports the ongoing primary growth of plants.

lateral meristem

In contrast to apical meristems, lateral meristems are responsible for the secondary growth of plants. This type of growth increases the thickness or girth of the plant.

There are two main types of lateral meristems: vascular cambium and cork cambium.

• Vascular cambium produces secondary xylem (wood) and secondary phloem, contributing to the plant's increased diameter.
  
• Cork cambium forms the protective outer layer known as cork.
  

Together, these two lateral meristems enable woody plants to grow wider and stronger, giving them the structural support they need to grow taller and live longer. Without lateral meristems, plants like trees wouldn't be able to develop the thick, sturdy trunks essential for their survival.

plant growth

Plant growth involves both primary and secondary growth, facilitated by meristematic tissues.

Primary growth, driven by apical meristems, ensures the elongation of roots and shoots, allowing the plant to expand in height and spread its root system.
Secondary growth, controlled by lateral meristems, increases the plant's thickness and provides robustness and structural integrity.

• Primary growth is essential for the plant's initial stages and helps in reaching light and gathering more nutrients.
  
• Secondary growth is crucial for mature plants, particularly trees, as it helps in increasing their strength and support.
  

Both processes are vital for a plant's development. Meristematic activity, occurring in both apical and lateral meristems, ensures that plants can grow, thrive, and reproduce effectively. The dynamic activity of these meristems is essential for the continual development and adaptability of plants.