Apical Meristem - Structure, Defination, Overview

Edited By Irshad Anwar | Updated on Jul 02, 2025 05:20 PM IST

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.

This Story also Contains

What Is Apical Meristem?
Types Of Apical Meristems
Where Is Apical Meristem Found?
Functions Of Apical Meristem
What Happens If The Apical Meristem Is Damaged Or Cut?
Root And Shoot Apical Meristem Structure
Tips, Tricks, And Strategies For Understanding Apical Meristem
Weightage Of Apical Meristem Questions In Exams
Types Of Questions Asked On Apical Meristem In Exams
Recommended Video On Apical Meristem

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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.

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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:

Exam Type	Weightage of Apical Meristem
CBSE Board Exams	4-6%
NEET	2-4%
Nursing Entrance Exams	2-3%
Paramedical Exams	1-2%

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:

Exam Type	Types of Questions
CBSE Board Exams	Definitions, short answers on location, and functions of apical meristem
NEET	MCQs on the role, location, and function of apical meristems
Nursing Entrance Exams	True/False questions on meristematic growth
Paramedical Exams	Case studies or scenario-based questions on plant growth disruptions

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Epidermal Tissue System	Ground Tissue System
Vascular Tissue System	Difference Between Monocot And Dicot Stem
Permanent Tissues	Parenchyma cells
Difference Between Tracheids And Vessels	Difference Between Xylem And Phloem

Recommended Video On Apical Meristem

Frequently Asked Questions (FAQs)

1. What is the difference between the structures of the root and the shoot apical meristem?

When we talk about the root apical meristem, the cells are synthesised in two different directions, while when we talk about the shoot apical meristem, cells are only synthesised in one direction.

2. Why are apical meristems called so?

The apical meristem is defined as a type of meristematic tissue that is present at the terminal parts of the plant, such as root tips and shoot apexes, so they are called apical. These help the plants grow.

3. How many types of apical meristem are present?

There are usually two main types of apical meristems classified according to location, i.e., the root apical meristem present at the tip of the root and the shoot apical meristem present at the tip of the shoot.

4. What are intercalary meristems?

An intercalary meristem is defined as a kind of primary meristematic tissue that possesses cells that can divide. These help promote the growth of the plant. They are present at the base of internodes. It is present in grasses.

5. What is Apical Meristem?

The apical meristem is the collection of undifferentiated cells located at the shoot and root tip responsible for the main plant growth.

6. What is the Function of Apical Meristem?

The primary role of the apical meristem is to allow for cell division as well as differentiation in order for the plant to grow upwards with shoots and downwards with roots.

7. What Happens if the Apical Meristem is Damaged or Cut?

If the apical meristem is damaged, the plant will fail to continue growth in this area, and lateral growth may become dominant. This is especially the case for shoot apical meristems that are cut.

8. Where is Apical Meristem Found Class 9?

The apical meristem is found at the apex (tip) of the shoot and root of plants, facilitating their elongation.

9. How does the apical meristem contribute to plant growth?

The apical meristem contributes to plant growth through cell division, elongation, and differentiation. It produces new cells that eventually form all the tissues and organs of the plant's shoot and root systems, allowing the plant to grow taller and develop new leaves, branches, and flowers.

10. What role do plant hormones play in regulating apical meristem activity?

Plant hormones, particularly auxins and cytokinins, play crucial roles in regulating apical meristem activity. Auxins promote cell elongation and maintain apical dominance, while cytokinins stimulate cell division. The balance between these hormones influences meristem size, cell division rates, and overall plant growth patterns.

11. How do environmental factors affect apical meristem activity?

Environmental factors such as light, temperature, and nutrient availability can significantly affect apical meristem activity. For example, increased light can stimulate meristem activity and promote growth, while extreme temperatures or nutrient deficiencies can slow or halt meristem function, affecting overall plant development.

12. How does the apical meristem contribute to leaf formation?

The apical meristem contributes to leaf formation through a process called leaf primordia initiation. Small groups of cells in the peripheral zone of the shoot apical meristem begin to divide rapidly and bulge outward, forming leaf primordia. These primordia then develop into fully formed leaves through further cell division, expansion, and differentiation.

13. How do cytokinins and auxins interact to regulate apical meristem function?

Cytokinins and auxins interact in a complex balance to regulate apical meristem function. Cytokinins promote cell division and meristem maintenance, while auxins promote cell elongation and differentiation. Their relative concentrations in different parts of the meristem help establish distinct functional zones and guide overall meristem activity and plant development.

14. What are the key zones of the shoot apical meristem?

The shoot apical meristem typically consists of three main zones: 1) The central zone, containing slowly dividing stem cells, 2) The peripheral zone, where cells divide more rapidly and begin to differentiate, and 3) The rib zone, which contributes to the formation of the stem's inner tissues.

15. How does the structure of the root apical meristem differ from the shoot apical meristem?

The root apical meristem differs from the shoot apical meristem in that it has an additional structure called the root cap, which protects the meristem as the root grows through soil. The root apical meristem also has a quiescent center, a region of slowly dividing cells that maintains the stem cell population.

16. What is apical dominance and how does it relate to the shoot apical meristem?

Apical dominance is the phenomenon where the main central stem of a plant grows more vigorously than its side branches. It's controlled by the shoot apical meristem, which produces auxin. This hormone inhibits the growth of lateral buds, ensuring that the plant's resources are primarily directed towards vertical growth.

17. How does the apical meristem maintain its stem cell population?

The apical meristem maintains its stem cell population through a delicate balance of cell division and differentiation. Stem cells in the central zone divide slowly, replenishing themselves while also producing daughter cells that move to the peripheral zone. Signaling molecules and transcription factors help maintain this balance and prevent premature differentiation.

18. What is phyllotaxy and how is it determined by the apical meristem?

Phyllotaxy refers to the arrangement of leaves on a plant stem. It is determined by the patterns of leaf primordia initiation in the shoot apical meristem. The specific phyllotactic pattern (e.g., alternate, opposite, or whorled) is influenced by chemical signals and mechanical forces within the meristem, ensuring efficient light capture and resource distribution.

19. What is the difference between primary and secondary meristems?

Primary meristems, including the apical meristem, are responsible for primary growth (increase in length). Secondary meristems, such as vascular cambium and cork cambium, are responsible for secondary growth (increase in girth). The apical meristem is a primary meristem present from the plant's embryonic stage, while secondary meristems develop later in the plant's life.

20. What is the difference between determinate and indeterminate growth in relation to the apical meristem?

In determinate growth, the apical meristem eventually transforms into a terminal structure (like a flower), ending further growth of that shoot. In indeterminate growth, the apical meristem continues to produce new cells indefinitely, allowing continuous growth. This difference is crucial in determining plant form and reproductive strategies.

21. What role does the apical meristem play in plant tropisms?

The apical meristem is crucial in plant tropisms - directional growth responses to environmental stimuli. For example, in phototropism, light perception leads to auxin redistribution in the apical meristem, causing differential growth that bends the stem towards light. Similarly, the root apical meristem is involved in gravitropism, directing root growth downward.

22. How does the apical meristem transition from vegetative to reproductive growth?

The transition from vegetative to reproductive growth involves a shift in the apical meristem's activity. Environmental cues (like day length) and internal signals trigger changes in gene expression within the meristem. This causes the meristem to stop producing leaves and instead initiate the formation of floral organs, transforming into a floral meristem.

23. How does the concept of stem cell niche apply to the apical meristem?

The stem cell niche in the apical meristem refers to the microenvironment that maintains stem cell identity and function. It includes the stem cells themselves and surrounding cells that provide necessary signals. This niche, particularly in the central zone, ensures a constant supply of undifferentiated cells for ongoing plant growth and development.

24. What is the role of the apical meristem in seasonal growth patterns?

The apical meristem responds to seasonal cues, altering its activity accordingly. In temperate plants, it may slow or stop activity during winter, forming a winter bud. As conditions improve in spring, the meristem resumes active growth. This responsiveness to seasonal changes allows plants to synchronize their growth with favorable environmental conditions.

25. What are meristemoids and how do they relate to the apical meristem?

Meristemoids are small, undifferentiated cells that retain the ability to divide. While not part of the apical meristem itself, they are derived from it and play a role in the formation of specialized structures like stomata. Meristemoids represent an intermediate stage between the primary meristem and fully differentiated cells.

26. What is the significance of the apical meristem in plant evolution?

The apical meristem has been crucial in plant evolution, allowing for the development of complex body plans and diverse growth forms. Variations in meristem structure and activity have contributed to the evolution of different plant lineages, from simple bryophytes to complex flowering plants, enabling plants to colonize and thrive in various terrestrial environments.

27. What is the quiescent center in the root apical meristem and why is it important?

The quiescent center is a group of slowly dividing cells at the heart of the root apical meristem. It's crucial for maintaining the stem cell population in the root meristem. The quiescent center acts as an organizer, sending signals to surrounding cells to maintain their stem cell identity and prevent premature differentiation.

28. What is the role of the apical meristem in determining plant architecture?

The apical meristem plays a crucial role in determining plant architecture by controlling the rate and pattern of stem elongation, leaf formation, and branching. Through its influence on phyllotaxy, internode length, and lateral bud development, the apical meristem shapes the overall form and structure of the plant.

29. How does the apical meristem contribute to plant adaptations to environmental stress?

The apical meristem can respond to environmental stress by altering its activity. For example, under drought conditions, it may slow cell division and produce smaller, thicker leaves to conserve water. In response to shade, it may increase stem elongation to reach more light. These plastic responses allow plants to adapt to changing environmental conditions.

30. How do epigenetic factors influence apical meristem function?

Epigenetic factors, such as DNA methylation and histone modifications, play important roles in regulating gene expression in the apical meristem. These modifications can influence cell fate decisions, meristem maintenance, and the transition to flowering. Epigenetic regulation allows for flexible responses to environmental conditions without changing the DNA sequence.

31. What is the role of sugar signaling in apical meristem function?

Sugar signaling plays an important role in apical meristem function. Sugars act not just as energy sources but also as signaling molecules. They can influence cell division rates, affect the expression of key regulatory genes, and interact with hormone signaling pathways. Sugar availability and signaling help coordinate meristem activity with the plant's overall energy status.

32. How does the structure of the apical meristem differ between monocots and dicots?

While both monocots and dicots have apical meristems, there are structural differences. Dicot shoot apical meristems typically have distinct tunica and corpus layers, with the tunica dividing anticlinally. Monocot meristems often lack this clear layered structure. These differences reflect the distinct developmental patterns and leaf arrangements in these two groups.

33. How does the apical meristem contribute to plant defense mechanisms?

The apical meristem can contribute to plant defense in several ways. It can produce defensive compounds or structures (like trichomes) in newly formed tissues. The meristem's ability to quickly generate new growth can help plants recover from herbivore damage. Additionally, systemic acquired resistance signals can prime the meristem to respond more quickly to future threats.

34. What is the significance of plasmodesmata in apical meristem function?

Plasmodesmata, the cytoplasmic channels connecting plant cells, are crucial for apical meristem function. They allow for the movement of signaling molecules, hormones, and even some proteins and RNAs between cells. This cell-to-cell communication is essential for coordinating cell division, differentiation, and maintaining the overall organization of the meristem.

35. How does wounding or removal of the apical meristem affect plant growth?

Wounding or removal of the apical meristem, such as through pruning or herbivory, can dramatically alter plant growth. It often results in the release of lateral buds from apical dominance, leading to increased branching. In some cases, a new apical meristem may form from nearby tissue, allowing the plant to resume vertical growth.

36. How do plant pathogens affect the apical meristem?

Some plant pathogens specifically target the apical meristem, as it's a crucial control center for plant growth. Viral, bacterial, or fungal infections can disrupt meristem function, leading to abnormal growth patterns, stunted development, or even plant death. The meristem's response to pathogens is an important aspect of plant defense mechanisms.

37. What is the relationship between the apical meristem and axillary meristems?

Axillary meristems, located in the axils of leaves, are derived from cells of the apical meristem. While the apical meristem drives primary growth at the shoot tip, axillary meristems remain dormant due to apical dominance. If the apical meristem is damaged or its dominance is reduced, axillary meristems can activate, leading to branching.

38. How does the apical meristem contribute to plant regeneration?

The apical meristem plays a crucial role in plant regeneration. Its stem cells can give rise to entire new plant organs or even whole plants. In tissue culture, apical meristem tissue is often used to propagate plants vegetatively, as it can regenerate shoots and roots. This capacity for regeneration is a key aspect of plant plasticity and survival.

39. What is the role of the WUSCHEL-CLAVATA feedback loop in the shoot apical meristem?

The WUSCHEL-CLAVATA feedback loop is a key regulatory mechanism in the shoot apical meristem. WUSCHEL (WUS) promotes stem cell identity, while CLAVATA (CLV) genes restrict WUS expression. This balance helps maintain the proper size and organization of the meristem. Disruptions to this loop can lead to abnormal meristem size and function.

40. How does the apical meristem maintain its organization despite continuous cell division and differentiation?

The apical meristem maintains its organization through a balance of cell division, differentiation, and positional signaling. Stem cells in the central zone replenish themselves while producing daughters that differentiate. Gradients of signaling molecules and transcription factors help maintain distinct functional zones. This dynamic yet stable organization allows for continuous growth while preserving meristem structure.

41. What is the apical meristem and where is it located in plants?

The apical meristem is a region of actively dividing cells located at the tips of roots and shoots in plants. It is responsible for primary growth, which increases the length of stems and roots. In shoots, it's found at the very tip of the stem, while in roots, it's protected by a root cap.

42. How does nutrient availability affect apical meristem function?

Nutrient availability significantly impacts apical meristem function. Adequate nutrients are essential for cell division and differentiation. Nutrient deficiencies can alter meristem activity, affecting growth rates and patterns. Some nutrients, like nitrogen, can influence hormone balances in the meristem. The meristem's response to nutrient availability helps plants allocate resources efficiently for growth.

43. How do mobile signaling molecules regulate apical meristem function?

Mobile signaling molecules, such as small peptides, RNAs, and hormones, move between cells to coordinate apical meristem activity. For example, CLAVATA3 peptide moves from the outer layers to inner layers of the meristem to regulate WUSCHEL expression. These mobile signals help maintain meristem organization and coordinate growth responses.

44. What is the relationship between the apical meristem and plant hormones other than auxin and cytokinin?

While auxin and cytokinin are primary regulators, other hormones also influence apical meristem function. Gibberellins promote stem elongation, affecting internode length. Abscisic acid can inhibit growth under stress conditions. Brassinosteroids influence cell expansion and division. The interplay of these hormones fine-tunes meristem activity and plant development.

45. How does the apical meristem respond to mechanical forces?

The apical meristem can sense and respond to mechanical forces. Pressure from surrounding tissues can influence cell division planes and rates. Mechanical stress can also affect the expression of genes involved in meristem maintenance and organ initiation. This mechanosensitivity allows the meristem to adapt its growth to physical constraints and opportunities in its environment.

46. What is the role of the apical meristem in plant memory and acclimation?

The apical meristem can play a role in plant memory and acclimation to environmental stresses. Exposure to stress can lead to epigenetic changes in meristematic cells, potentially affecting how these cells and their progeny respond to future stresses. This form of "stress memory" in the meristem can contribute to improved plant adaptation over time.

47. How does light quality affect apical meristem activity?

Light quality significantly affects apical meristem activity. Different wavelengths of light can influence hormone production and signaling within the meristem. For example, red to far-red light ratios can affect stem elongation and branching patterns. Blue light can influence phototropic responses. These light-mediated effects on the meristem help plants optimize their growth in varying light environments.

48. What is the relationship between the apical meristem and plant circadian rhythms?

The apical meristem is influenced by and contributes to plant circadian rhythms. Many genes involved in meristem function show circadian expression patterns. The circadian clock can influence the timing of cell divisions and organ initiation in the meristem. This integration of circadian rhythms with meristem activity helps synchronize plant growth with daily and seasonal cycles.

49. What is the role of reactive oxygen species (ROS) in apical meristem function?

Reactive oxygen species (ROS) play a complex role in apical meristem function. While high levels of ROS can damage cells, controlled ROS production is important for normal meristem activity. ROS can act as signaling molecules, influencing cell division, differentiation, and stress responses. The balance of ROS production and scavenging is crucial for maintaining meristem health and function.