Apical Meristem - Structure, Defination, Overview

The apical meristem is a constituent element of the plant's biology. it is involved in the processes of plant growth and development. Apical meristem cells also represent a foundation for tissues and organs in a plant. These meristematic tissues are involved in growth as they produce new cells, which help plants grow in height, length, and complexity. Root and shoot apical meristem are described in the class 12 biology chapter Anatomy of flowering plants. It is an important topic while studying for NEET, AIIMS, nursing or paramedical entrance exams.

Read More:

• Anatomy of Flowering Plants
• Morphology Of Flowering Plants
• Monocot and Dicot Plants
• Anatomy of Root, Stem and Leaf

What Is Apical Meristem?

Apical meristem is the region where the cells in the plant's roots and shoots divide very quickly and are highly undifferentiated at the tips. These cells help in primary growth, which makes the plants grow in two directions: upward (shoots) and downward (roots). Cell division in the apical meristem helps in the elongation and development of several organs of the plant.

Types Of Apical Meristems

The apical meristems are of mainly two types:

Shoot Apical Meristem

• The shoot apical meristem is located at the tip of the plant shoot.
• It produces new stem tissues and flowers and leaves.
• In plants, this aids in upward growth.

Root Apical Meristem

• It is located at the root tip, it is covered with a root cap.
• This meristem aids in the downward movement of the root in soil.

Where Is Apical Meristem Found?

Apical meristem is found in two chief parts of the plants:

• Shoot Apical Meristem: The shoot apical meristem is the tip of the shoot part of a plant.
• Root Apical Meristem: The root apical meristem is the tip of the root, behind its covering root cap.

In Class 9, students are introduced to the following topics with a focus on how the apical meristems act as an assistive tool for the growth of plants above and below the soil surface.

Functions Of Apical Meristem

The apical meristem performs very important functions in the growth and survival of a plant. Some of the primary functions are as follows:

• Cell Division: The apical meristem continuously divides generating new cells for growth.
• Primary Growth: The apical meristem provides vertical growth, directly causing an increase in the dimensions of the plant body.
• Differentiation: The cells produced by the apical meristem start to differentiate into other tissues like leaves, stems, and roots.
• Shoot and Root Growth: This promotes the elongation of shoots and roots. Hence it enables a plant to effectively capture sunlight (through shoots) and nutrient uptake (through roots).

What Happens If The Apical Meristem Is Damaged Or Cut?

• It usually interferes with plant growth, especially if damage to the apical meristem is extensive.
• Damage or cutting of the shoot apical meristem can cause the plant to stop growing upward.
• In some cases, lateral buds known as axillary buds become dominant and cause the plant to spread out horizontally rather than growing upwards.
• On roots, damage to the apical meristem inhibits root growth and thus affects the uptake of water and nutrients in the plant.

Root And Shoot Apical Meristem Structure

There are specific areas that organise the shoot apical meristem and the root apical meristem as well:

Organisation Of Shoot Apical Meristem

• Central Zone: Comprises cells that slowly divide and replace the stem cell population.
• Peripheral Zone: Comprises the formation of lateral structures like leaves and branches.
• Rib Meristem: Comprise in the formation of the stem below the meristem.

Organisation Of The Root Apical Meristem

• Quiescent Center: It is a store of relatively quiescent cells and the reservoir for root growth.
• Proximal Meristem: Produces new cells and is responsible for the elongation of the root.
• Root Cap: It guards the apical meristem of the root as the root pushes its way through the soil.

Tips, Tricks, And Strategies For Understanding Apical Meristem

To get a better understanding of the apical meristem concept, here are some tips and tricks:

• Study Aids: Draw diagrams showing where the root and shoot apical meristems are located, as well as the zones in each.
• Mnemonic: "Use SAM and RAM, where the Shoot Apical Meristem (SAM) is on top, and the Root Apical Meristem (RAM) has to be at the bottom.".
• Multimedia: View animations or videos illustrating how apical meristems stimulate growth in plants.
• Real-Life Example: Observe plant growth in the surroundings. For example, cutting the tip of a plant arrests its vertical growth but promotes side branching.
• Flashcards: Use flashcards to memorize key functions and zones of the apical meristem.

Weightage Of Apical Meristem Questions In Exams

The weightage of questions related to apical meristem is given below:

Types Of Questions Asked On Apical Meristem In Exams

The table given below indicates the types of questions related to apical meristem topic asked in various exams:

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