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Maharashtra State BoardSSC (Marathi Semi-English) 9th Standard [इयत्ता ९ वी]
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Syllabus

Transportation of Water in Plants

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Topics

  • Root Pressure
  • Transpiration Pull
  • Experiment

Root Pressure:

Root pressure is the process by which water and minerals from the soil are absorbed by root cells and transported upward through the plant. This happens due to a difference in concentration between the water and minerals in the soil and those inside the root cells.

Working:

  1. Absorption: The root cells absorb water and minerals from the soil, causing them to swell and become turgid (firm due to water pressure).
  2. Pressure Creation: The turgid cells exert pressure on adjacent cells, pushing water and minerals into the xylem (the tissue responsible for water transport).
  3. Formation of a Water Column: As water and minerals are continuously pushed forward, they create a continuous column of water inside the xylem.
  4. Upward Movement: This root pressure is strong enough to lift the water column upward in small plants, shrubs, and small trees.

Root pressure ensures that water and minerals are steadily transported to the upper parts of the plant, supplying the necessary nutrients for growth and photosynthesis. However, in tall trees, additional mechanisms like transpiration pull are required to move water to greater heights.

Absorption with the help of roots

Transpiration Pull:

Transpiration pull is a mechanism by which plants transport water from the roots to the leaves through the xylem. This process relies on water loss in the form of vapour through tiny pores on the leaves called stomata.

  • It maintains the continuous upward flow of water and nutrients from the roots to the leaves.
  • It regulates temperature in plants by cooling them through water evaporation and helps in maintaining water balance within the plant.
  • Transpiration pull is a vital process that supports plant hydration, nutrient distribution, and overall growth.

Steps in Transpiration Pull:

  1. Water Loss Through Stomata: Stomata are surrounded by guard cells that control their opening and closing. Through these pores, water evaporates from the surface of the leaves into the atmosphere.
  2. Creation of a Water Deficit: When water evaporates, the water level in the epidermal cells of the leaf decreases, creating a deficit.
  3. Upward Movement of Water: To compensate for the lost water, more water is drawn up from the xylem. This movement creates a continuous column of water being pulled upward from the roots to the leaves, driven by the evaporation process.
  4. Role of Transpiration: Transpiration not only helps in water movement but also aids in the absorption of water and minerals by creating a suction force. It ensures the distribution of nutrients to all parts of the plant.
  5. Night-Time Role of Root Pressure: While transpiration pull is the dominant mechanism during the day, root pressure assists in pushing water upward during the night when stomata are closed.

Transpiration through Leaves

Experiment

1. Aim: To demonstrate how water is transported through the xylem in plants.

2 Requirements: a small plant (e.g., balsam or tuberose) with roots intact, a beaker, water, eosin or safranin stain, and a stand to hold the plant upright.

3. Procedure:

  • Take a small plant with its roots and wash them thoroughly to clean any soil or dirt.
  • Fill a beaker with water and add a few drops of eosin or safranin stain to colour the water.
  • Place the cleaned plant in the stained water, ensuring the roots are submerged.
  • Secure the plant in an upright position using a stand.
  • Leave the setup for 2-3 hours.
  • Observe the stem and the veins of the leaves for any changes in colour.

Root Pressure

4. Conclusion: After a few hours, the stained water is observed to travel through the stem and into the veins of the leaves, turning them red. This shows that water is transported through the plant's xylem vessels, from the roots to other parts of the plant. This experiment illustrates the process of water transportation in plants.

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