Question

hcrease in gith of the plant as a result of the activities of primary and secondary lateral meristems is called (a) pimary growth (b) lateral growth (c) secondary growth (d) intercalary growth.

Short answer

(c) secondary growth

Step-by-step solution

Understand plant growth types

Growth in the height of the plant primarily happens due to the cell division in the apical meristems, which is referred to as primary growth. This leads to the lengthening of the plant. In contrast, growth in the thickness of the plant is due to activities in both primary and secondary lateral meristems, with the latter being responsible for the secondary growth that increases the girth or diameter of the plant.

Identify the correct option

Given that the question refers to an increase in the girth of the plant as a result of the activities of primary and secondary lateral meristems, we identify this type of growth as 'secondary growth'.

Choose the correct answer

From the understanding of plant growth and the options provided, we conclude that the correct answer is (c) secondary growth.

Key concepts

Primary Growth in Plants

Primary growth in plants is a fundamental process that leads to an increase in the plants' length. This growth occurs at the apical meristems, which are located at the tips of roots and shoots.

Apical meristems are regions of intense cell division, where cells proliferate rapidly and then elongate, contributing to the lengthening of the plant. As these new cells mature, they help to form various plant organs, such as leaves, flowers, and branches.

Understanding primary growth is crucial for gardeners and farmers as it influences the height and overall size of plants, which can be important for plant care and crop yields. For instance, in agriculture, promoting primary growth can lead to taller and potentially more productive plants.

Lateral Meristems

Lateral meristems are responsible for the secondary growth in plants, which includes an increase in girth or thickness. Unlike apical meristems, lateral meristems are found in the circumference of the plant stem and root.

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

Vascular Cambium

The vascular cambium is responsible for producing new vascular tissues - xylem and phloem. The xylem helps transport water and nutrients from the roots to other parts of the plant, while phloem carries sugar and organic substances.

Cork Cambium

The cork cambium generates the outer protective layer known as the bark. Together, these meristems contribute to the plant's overall sturdiness and ability to transport water and nutrients efficiently.

Apical Meristems

Apical meristems are dynamic regions found at the growing tips of the plant, such as the top of the stem and the roots' tips. They are composed of undifferentiated, or totipotent, cells capable of continuous division.

These cells give rise to all the specialized cells needed for the plant to grow taller and develop fully. For example, apical meristems are directly involved in the development of leaves and flowers. Thus, understanding the role of apical meristems is essential for grasping how plants grow and develop from a seed into a mature organism, capable of reproduction.

Plant Growth Types

Plants exhibit two main types of growth: primary and secondary.

Primary Growth

As covered earlier, primary growth occurs at the apical meristems and results in the plant's elongation. It's the growth that occurs first and is primarily observed in all seedlings as they sprout and begin to mature.

Secondary Growth

Secondary growth is responsible for increasing the plant's thickness and involves both primary and secondary lateral meristems. This type of growth is common in woody plants, trees, and shrubs, contributing to the thickness of their stems and roots over time.

Recognizing these growth patterns is helpful for anyone interested in botany, agriculture, or forestry, as they play a key role in plant structure and development.