Problem 110 - Objective Biology for NEET

Question

Cambium wing forms cells towards (a) Inner side of ring (b) Outer side of ring (c) Both side of ring (d) They do not form cells

Step-by-Step Solution

Answer

The correct answer is (c) Both side of ring

Step 1: Understand what the cambium ring is

The cambium is a layer of tissue between the wood and the bark of the stem from which new growth in diameter (lateral growth) occurs in stems and roots. The cambium produces new cells which push older cells outwards.

Step 2: Where cells are formed

The cambium creates new cells, these new cells give rise to secondary xylem (wood) and phloem (bark). It forms cells towards both the inner side (towards the wood) and outer side (towards the bark) of the ring.

Step 3: Determine correct answer

Based on the previous steps, the cambium ring forms cells towards both sides of the ring.

Key Concepts

Lateral Growth

Lateral growth is a fascinating process, essential for the thickening of plant stems and roots. This type of growth increases the girth or width of plants, allowing them to better support their expanding structures. It all starts with the cambium, a thin layer found between woody and bark tissues. As the cambium divides, it adds layers of cells to both the inside and outside.
These new cells enable the plant to gain more structural stability, leading to thicker trunks and stems. It’s through lateral growth that trees can become massive and robust, supporting sprawling canopies. This process is crucial for plants that remain in a single location, as it allows them to extend above competing vegetation to capture sunlight, as well as growing wider to form strong, stable trunks.

Secondary Xylem

Secondary xylem, more commonly known as wood, is generated from the cells produced by the cambium. As plants experience lateral growth, these cells add to the internal structure of the plant. Secondary xylem provides essential support and plays a significant role in transporting water and nutrients from the roots upwards to the leaves and rest of the plant.
Each year, as the cambium continues to form new xylem cells, a tree adds to its woody layers, visible as rings in a cross-section of the trunk. These rings can help us determine the age of a tree and provide insight into environmental conditions over the years. In addition to structural support, secondary xylem is crucial for a plant's water management system, serving as a network for fluid movement throughout the plant.

Secondary Phloem

Secondary phloem, often referred to as part of the plant’s bark, plays an integral role in a plant's nutrient distribution. The cambium not only produces secondary xylem for water transport but also secondary phloem, functioning as the pathway for transporting sugars and other metabolic products downwards or to storage tissues.

• Secondary phloem is essential for distributing sugars produced via photosynthesis in the leaves to other parts of the plant for growth and storage.
• This tissue is crucial for the plant's survival during periods when photosynthesis may not be active, such as during winter or nighttime.
• Over time, as more secondary phloem is produced, older layers are pushed outwards and contribute to the formation of the bark.

Understanding the role of secondary phloem is vital to grasp how plants maintain their energy distribution networks.

Tissue Layer in Plants

The tissue layer in plants that we call the cambium is key to understanding plant growth. This narrow band of actively dividing cells between the xylem and the phloem forms a continuous ring around the stem or trunk. This layer plays a critical role in both lateral growth and in forming secondary xylem and phloem.
By constantly dividing and creating new cells, the cambium enables the plant to thicken. Unlike animals, which often grow through increasing the size of existing cells, plants expand by adding new cells via these specialized tissue layers. Thus, the cambium helps not only in growth but also ensures that a plant's structural and transport needs are met as it expands.
In essence, understanding the function and location of the cambium within the plant tissue systems is essential for appreciating how plants achieve large sizes and remain sustainable over long periods.