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🌿 Plant Physiology – The Vital Functions in Plants (Part 2)

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🌱 Transpiration – The Loss of Water in Plants

Transpiration is the process through which plants lose water vapor from their leaves, primarily through small openings called stomata. Although it may seem like an unnecessary loss of water, transpiration is essential for plants' survival. It helps with the uptake of water and minerals from the soil, cooling the plant, and maintaining the flow of nutrients.

Types of Transpiration:

1. Cuticular Transpiration: Water vapor diffuses directly through the cuticle of the plant.

2. Stomatal Transpiration: Occurs through the stomata, pores found mainly on the underside of leaves.

3. Lenticular Transpiration: Water vapor loss through lenticels, small pores in the stems and branches of some plants.

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💧 Mechanism of Transpiration

The process of transpiration is driven by the following factors:

• Evaporation: The water inside the plant evaporates into the atmosphere.

• Water potential: The loss of water creates a negative pressure, pulling more water from the roots to replace the lost moisture.

• Cohesion and Adhesion: Water molecules stick to each other (cohesion) and to the plant’s vascular tissues (adhesion), allowing water to move upward.

The Role of Stomata in Transpiration

Stomata are tiny pores surrounded by guard cells that regulate water loss by opening and closing in response to environmental conditions. During the day, stomata open to allow gas exchange for photosynthesis but also allow water vapor to escape. At night, when photosynthesis doesn’t occur, the stomata close to conserve water.

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Transpiration and Water Transport in Plants

The process of transpiration creates a transpirational pull, which helps draw water from the roots through the plant's vascular system. The xylem vessels play a significant role in this process, carrying water and dissolved minerals from the roots to other parts of the plant.

Importance of Transpiration:

1. Cool the plant: By evaporating water from the leaves, transpiration helps maintain an optimal temperature.

2. Nutrient transport: Transpiration assists in the upward movement of minerals and nutrients from the soil to the plant.

3. Turgor pressure: The loss of water through transpiration helps maintain turgor pressure in plant cells, which keeps the plant upright and supports growth.

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🌾 Mineral Nutrition in Plants

Mineral nutrients are essential for plant growth and are taken up from the soil. Plants need macronutrients in large quantities and micronutrients in smaller quantities to perform various functions like cell division, energy transfer, and protein synthesis.

Macronutrients in Plants:

1. Nitrogen (N): Essential for protein synthesis, chlorophyll formation, and growth.

2. Phosphorus (P): Vital for ATP production, root development, and DNA synthesis.

3. Potassium (K): Important for stomatal function, enzyme activation, and stress tolerance.

4. Calcium (Ca): Crucial for cell wall structure, cell division, and maintaining membrane integrity.

5. Magnesium (Mg): A key component of chlorophyll and helps in enzyme activation.

6. Sulfur (S): Needed for the synthesis of amino acids, vitamins, and enzymes.

Micronutrients in Plants:

1. Iron (Fe): Essential for chlorophyll synthesis and electron transfer during photosynthesis.

2. Copper (Cu): Involved in respiration and photosynthesis.

3. Zinc (Zn): Important for protein synthesis and growth regulation.

4. Manganese (Mn): Plays a role in photosynthesis and enzyme activation.

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🌾 Uptake of Mineral Nutrients by Roots

Roots absorb water and dissolved minerals from the soil through the root hairs, which increase the surface area for absorption. The process of nutrient uptake can be active (requiring energy) or passive (no energy required).

Active Transport:

Minerals are moved into root cells against a concentration gradient, requiring energy in the form of ATP.

Passive Transport:

Minerals move along with water through osmosis and diffusion.

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🧪 Role of Xylem in Mineral Transport

The xylem tissue is responsible for transporting water and dissolved minerals from the roots to the leaves and other parts of the plant. Xylem cells are dead and have thick walls to allow the unidirectional flow of water.

Xylem Structure:

1. Tracheids: Long, tapering cells that help in the movement of water and provide structural support.

2. Vessel elements: Shorter, wider cells that form continuous tubes for the efficient transport of water.

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⚡ NEET PYQ Alerts – Transpiration and Mineral Nutrition

1. The loss of water from plant leaves is called:

   • A) Photosynthesis

   • B) Respiration

   • C) Transpiration

   • D) Germination

   • Answer: C) Transpiration

2. Which of the following nutrients is essential for chlorophyll formation?

   • A) Nitrogen

   • B) Magnesium

   • C) Phosphorus

   • D) Calcium

   • Answer: B) Magnesium

3. The process by which plants absorb water and nutrients from the soil is called:

   • A) Evaporation

   • B) Osmosis

   • C) Transpiration

   • D) Absorption

   • Answer: D) Absorption

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🌿 Conclusion and What’s Next?

In Part 2, we delved into transpiration, the loss of water from plants, and the vital process of mineral nutrition, which is essential for plant health and growth. Understanding these processes is key to appreciating how plants interact with their environment.

In Part 3, we will discuss plant growth regulators (phytohormones) and their role in regulating plant growth, as well as the process of photosynthesis in detail.

Stay tuned for more information in the next blog!

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