Control and coordination in Plants

Control and Coordination in Plants

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Control and Coordination in Plants

Plants may seem still and quiet, but beneath their serene exterior lies a fascinating world of control and coordination. Unlike animals with nervous systems, plants don’t have brains or nerves. Yet, they can sense their environment, respond to stimuli, and regulate their growth and development. How do they achieve this seemingly complex feat?
Coordination in Plants - Types of Movements, Hormones, Examples & FAQs

Why is it Important?

Maintaining control and coordination is vital for plant life. It allows them to:

  • Grow towards sunlight: Plants can bend their stems towards the sun for optimal photosynthesis, the process by which they convert light energy into food.
  • Respond to gravity: Roots grow downwards to anchor the plant and reach water, while shoots grow upwards towards light.
  • Defend themselves: Plants can produce chemicals to deter herbivores or close their stomata (tiny pores) to conserve water during drought.
  • Reproduce: Flowering is precisely timed to attract pollinators and ensure successful seed production.

Plant Hormones and Signaling

Plants may not have a nervous system like animals, but they still have a complex way of communicating and coordinating their growth and development. This communication happens through chemical messengers called plant hormones. These hormones, produced in tiny amounts at specific sites within the plant, travel throughout the organism, influencing a wide range of processes.

Types of plant hormone. growth promoters and growth inhibitors include auxins, gibberelins, cytokinins, ethylene, abscicic acid

How Plant Hormones Work

Imagine a plant as a giant orchestra, with each cell acting as an instrument. Plant hormones act like the conductor, coordinating the entire performance. They work at incredibly low concentrations, but their effects are far-reaching. Here’s a simplified breakdown of how they achieve this feat:

  1. Production: Hormones are synthesized in specific tissues within the plant. For instance, auxin is produced in the shoot tips, while cytokinins are made in the roots.
  2. Transport: Once produced, hormones can travel through specialized channels within the plant or diffuse from cell to cell. This targeted movement allows them to reach specific areas where they are needed.
  3. Signaling: When a hormone reaches its target cell, it binds to a receptor protein on the cell membrane. This binding triggers a cascade of events within the cell, ultimately leading to changes in gene expression and cellular activity.

Different Plant Hormones and their Roles

Plants have a whole orchestra of hormones, each playing a distinct role. Here are some of the key players:

  • Auxin: The “growth director,” auxin promotes stem elongation, root development, and cell division.

Mechanism of Phototropism in Plants

  • Cytokinins: Auxin’s counterpart, cytokinins, encourage cell division and shoot growth. They also play a role in delaying leaf senescence (aging).
vector illustration of cytokinin Structure .
  • Gibberellins: These hormones are like the “growth accelerators,” promoting stem elongation, seed germination, and fruit development.
hand holding and caring a green plant over lighting background, planting tree, environment, background.agriculture, horticulture. plant growth evolution from seed to sapling, ecology concept.
  • Abscisic Acid (ABA): This hormone acts as the plant’s “stress manager,” helping it cope with drought, cold, and other environmental challenges.
Molecular formula of abscisic acid. Chemical formula of abscisic acid
  • Ethylene: Ethylene is a gaseous hormone with diverse functions, including fruit ripening, seed germination, and responses to wounding.
3d chemical structure of ethylene formula molecule. Scientific vector illustration isolated on white background.

Nervous System? Not Quite, But They Talk!

Imagine a plant sensing danger, sending a signal to its leaves, and triggering defenses. Sounds like something out of a science fiction movie, right? Well, it turns out plants can communicate and respond to their environment, but not in the same way animals do with a nervous system.

Plants Don’t Have Animal-Like Nerves


The classic definition of a nervous system involves specialized cells called neurons that transmit electrical signals. These neurons are like a network, carrying information throughout an animal’s body. Plants simply don’t have this kind of setup.

But Plants Can Still Talk!

Plants may not have neurons, but they have a fascinating way of communicating using electrical signals and chemical messengers called hormones.

  • Electrical Signals: When a plant part gets injured, for example, it can trigger an electrical wave that travels to other parts. This electrical message can warn other leaves to prepare for defense.
  • Chemical Messengers: Plants also use hormones to signal to different parts. These hormones can travel through the plant’s vascular system, similar to how blood carries messages in animals. Hormones can trigger various responses, like growth, flowering, or even attracting beneficial insects.

Environmental Responses in Plants

Plants may seem stationary, but they are surprisingly sophisticated organisms that can detect and respond to a wide range of environmental cues. This ability is essential for their survival and growth. Let’s delve into the fascinating world of environmental responses in plants!

Plant Detectives: Sensing the Environment

Plants lack the sensory organs of animals, but they possess a remarkable toolkit for perceiving their surroundings. Here are some key ways plants sense their environment:

  • Light: Plants have specialized photoreceptors that detect light intensity, duration, and wavelength. This information is crucial for processes like photosynthesis, flowering, and growth direction (tropisms, which we’ll discuss next).
  • Gravity: Plants can sense gravity through structures called statoliths. These starch-filled sacs within root tips and stems help roots grow downward and shoots grow upward.
  • Touch: Plants have touch-sensitive structures like trichomes (hairs) on their leaves and stems. Touching these can trigger defensive responses or growth adjustments.
  • Water: Plants can sense changes in water availability through specialized cells in their roots. This allows them to regulate water uptake and stomatal opening (tiny pores on leaves for gas exchange).
  • Temperature: Plants have mechanisms to perceive temperature fluctuations. This information helps them adapt to seasonal changes and avoid freezing damage.

Tropisms: The Power of Directional Growth

Tropisms are directed growth responses of plants in response to environmental stimuli. They are essentially a plant’s way of “growing” towards or away from something it needs or wants to avoid. Here’s why tropisms are significant:

Lesson Video: Plant Tropisms | Nagwa

  • Survival: Tropisms ensure plants grow in a way that maximizes their access to essential resources like sunlight and water, and minimizes exposure to harmful elements.
  • Development: Tropisms play a crucial role in plant development, influencing root growth direction, shoot orientation, and even leaf positioning for optimal light capture.
  • Reproduction: Tropisms can even influence flower and fruit development, ensuring better pollination and seed dispersal.

Symphony of Signals: Different Types of Tropisms

Plants exhibit a diverse range of tropisms, each fine-tuned to a specific environmental cue. Let’s explore some common types:

  • Phototropism: Growth towards light. Stems exhibit positive phototropism, reaching for sunlight for photosynthesis. Roots, conversely, show negative phototropism, growing away from light.

Mechanism of Phototropism in Plants,vector image

  • Gravitropism: Growth in response to gravity. Roots exhibit positive gravitropism, growing downward to access water and nutrients. Shoots display negative gravitropism, growing upwards towards light for photosynthesis.

Gravitropism. Geotropism. The Plant Differential Growth in Response to Gravity

  • Thigmotropism: Growth in response to touch. Climbing plants exhibit positive thigmotropism, using tendrils or other structures to grow around support structures.

Nastic movements -it is a directional movement in plants in response to touch. Mimosa pudica plant is folding up leaves when touched. Isolated vector flat illustration.

  • Hydrotropism: Growth in response to water availability. Roots exhibit positive hydrotropism, growing towards areas with more moisture in the soil.

Hydrotropism is the directional growth of plant's root towards water or moisture. hydrotropic movement. botany concept. tropic movement.


Control and coordination are essential for plant survival and success in diverse environments. Through hormonal signaling, the plant nervous system, and responses to environmental stimuli, plants adapt and thrive, demonstrating remarkable complexity and resilience in their interactions with their surroundings. Understanding these mechanisms enhances our appreciation for the extraordinary abilities of plants and their vital role in sustaining life on Earth.


  • Control and coordination in plants involve the regulation of various activities and responses to stimuli to ensure proper growth and adaptation to the environment.
  • Coordination in plant biology refers to the harmonious integration of different physiological processes within plants to achieve specific functions or responses.
  • The coordination system present in plants involves the integration of hormonal signaling, electrical signaling, and responses to environmental stimuli.
  • Hormones in plants control various physiological processes including growth, development, tropisms, and responses to environmental cues.
  • Auxins are the primary hormones responsible for controlling plant growth by regulating cell elongation and differentiation.
  • Ethylene is the hormone responsible for initiating the ripening process in plants, leading to changes in color, texture, and flavor in fruits.


  1. What is the significance of control and coordination in plant life?

    • A. It regulates growth and responses to stimuli
    • B. It determines plant coloration
    • C. It controls plant reproduction
    • D. It enhances plant photosynthesis
  2. Which of the following is not a plant hormone?

    • A. Auxin
    • B. Gibberellin
    • C. Insulin
    • D. Melatonin
  3. What is the main role of auxins in plants?

    • A. Promoting seed germination
    • B. Stimulating cell division
    • C. Controlling fruit ripening
    • D. Regulating cell elongation
  4. Which hormone is responsible for stimulating lateral bud growth in plants?

    • A. Gibberellin
    • B. Cytokinin
    • C. Ethylene
    • D. Abscisic acid
  5. How do plants respond to touch stimuli?

    • A. Hydrotropism
    • B. Phototropism
    • C. Thigmotropism
    • D. Gravitropism
  6. Which hormone is primarily responsible for fruit ripening in plants?

    • A. Gibberellin
    • B. Cytokinin
    • C. Auxin
    • D. Ethylene
  7. What is the function of the plant nervous system?

    • A. Regulating plant reproduction
    • B. Transmitting electrical signals
    • C. Producing plant hormones
    • D. Controlling plant coloration
  8. Which type of tropism involves the response to moisture levels?

    • A. Thigmotropism
    • B. Hydrotropism
    • C. Phototropism
    • D. Gravitropism
  9. What role do gibberellins play in plant growth and development?

    • A. Promoting seed dormancy
    • B. Stimulating stem elongation
    • C. Inducing leaf senescence
    • D. Inhibiting root growth
  10. Which hormone regulates the balance between shoot and root growth in plants?

  • A. Ethylene
  • B. Gibberellin
  • C. Cytokinin
  • D. Auxin
  1. What is the main function of plant hormones?
  • A. Generating energy for photosynthesis
  • B. Maintaining plant coloration
  • C. Regulating growth and development
  • D. Enhancing plant respiration
  1. Which hormone is responsible for bending towards light in plants?
  • A. Gibberellin
  • B. Cytokinin
  • C. Auxin
  • D. Ethylene
  1. What are the main systems involved in control and coordination in plants?
  • A. Nervous system and circulatory system
  • B. Hormonal system and reproductive system
  • C. Hormonal system and environmental responses
  • D. Digestive system and excretory system
  1. What is the significance of gravitropism in plants?
  • A. Regulating responses to touch
  • B. Controlling fruit ripening
  • C. Orienting root growth
  • D. Stimulating seed germination
  1. How do plants respond to changes in gravity?
  • A. Phototropism
  • B. Thigmotropism
  • C. Gravitropism
  • D. Hydrotropism
  1. Which hormone delays aging in plants?
  • A. Gibberellin
  • B. Auxin
  • C. Cytokinin
  • D. Ethylene
  1. What role do cytokinins play in plant development?
  • A. Stimulating seed germination
  • B. Promoting cell division
  • C. Inducing leaf senescence
  • D. Inhibiting root growth
  1. Which hormone promotes stem elongation in plants?
  • A. Ethylene
  • B. Gibberellin
  • C. Auxin
  • D. Cytokinin
  1. What is the primary function of ethylene in plants?
  • A. Stimulating leaf growth
  • B. Regulating fruit ripening
  • C. Promoting root elongation
  • D. Inducing seed dormancy
  1. Which hormone is responsible for stimulating cell elongation in plants?
  • A. Auxin
  • B. Gibberellin
  • C. Cytokinin
  • D. Ethylene

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