Problem 142 - Objective Biology for NEET

Question

The tissue made up of thin-walled rectangular cells responsible for the secondary growth is (a) Cortex (b) Xylem (c) Cambium (d) Pith

Step-by-Step Solution

Answer

The tissue responsible for secondary growth is (c) Cambium.

Step 1: Understanding Plant Tissue

Understanding the different types of plant tissues is a key point in solving the exercise. There are several types of plant tissues, including cortex, xylem, cambium, and pith. Each of these tissues has different functions in the plant.

Step 2: Identifying the Secondary Growth Tissue

Secondary growth in plants involves two types of tissues: vascular cambium and cork cambium. The cells of these tissues divide to produce new cells, leading to the thickening or second growth in stems and roots. So, among the options given, cambium is responsible for secondary growth.

Step 3: Choosing the Answer

Based on the above analysis, it is clear that the tissue responsible for secondary growth is cambium. Thus, the correct answer choice is (c).

Key Concepts

Understanding Plant Tissue

Plant tissues are vital for the structure and function of plants. In the context of secondary growth, it's essential to grasp the diversity of plant tissue types. Think of plant tissue as the building blocks of plants, where each type has a role in the plant's growth, nutrition, support, and survival.

For example, the cortex is involved in storage, the pith serves for storage and to transport nutrients across the plant's stems, and the xylem is crucial for water and nutrient movement from roots to leaves. Knowing these varied roles, we recognize that not all plant tissues contribute directly to secondary growth. This knowledge enhances our understanding of how plants develop structurally over time.

Diving into the Role of Vascular Cambium

The vascular cambium is one of the plant's most dynamic tissues. It's a thin layer of cells found between the wood (xylem) and bark (phloem) in the stems and roots of dicotyledonous plants. Functionally, it serves as a plant's growth engine, giving rise to secondary xylem (wood) and secondary phloem (inner bark).

Think of it as a magic ring in the stem's cross-section that continually multiplies, increasing the plant's girth during secondary growth. This growth is particularly evident in trees and shrubs, leading to the annual ring formation that tells the age of a tree and the environmental conditions it has endured.

Cambium Function and Its Importance

The cambium's function extends beyond just increasing the diameter of plants. It plays a crucial role in ensuring plants have the structural strength to stand tall and the ability to transport water and nutrients efficiently as they grow larger. Moreover, by producing new transport tissues, the cambium ensures that a mature plant maintains its metabolism, adapting to environmental challenges and damage.

The vascular cambium is, therefore, not just about growth, but also about the resilience and vitality of plants. Its role in secondary growth underpins the ability of trees and shrubs to live for many years, supporting ecosystems, and providing invaluable resources for human use.