Bihar Board - Class 11 biology - Chapter 11: Transport in plants Handwritten Notes

Transport in plants is a fundamental process that involves the movement of water, minerals, and nutrients to various parts of the plant. This chapter delves into the mechanisms of transport, including diffusion, osmosis, active transport, and bulk flow, emphasizing their role in plant growth and metabolism.

Key Points

1. Types of Transport

   • Passive Transport: Movement of molecules without energy expenditure.
     • Diffusion: Movement of molecules from higher to lower concentration.
     • Osmosis: Movement of water across a semi-permeable membrane from low to high solute concentration.
   • Active Transport: Energy-driven movement of molecules against their concentration gradient using carrier proteins.

2. Water Movement in Plants

   • Absorption of Water:
     • Roots absorb water from the soil through root hairs by osmosis.
   • Pathways of Water Movement:
     • Apoplast Pathway: Movement through cell walls and intercellular spaces.
     • Symplast Pathway: Movement through the cytoplasm connected by plasmodesmata.
   • Endodermis and Casparian Strip: Regulate water and mineral entry into the vascular tissue.

3. Transpiration

   • Loss of water vapor from aerial parts of the plant, primarily through stomata.
   • Functions:
     • Creates a transpiration pull for water movement.
     • Cools the plant and maintains the flow of minerals.

4. Transport of Water

   • Xylem: Conducts water and minerals from roots to other parts of the plant.
     • Mechanism: Cohesion-tension theory explains the ascent of sap through transpiration pull, cohesion, and adhesion forces.

5. Transport of Organic Solutes

   • Phloem: Transports food (sucrose) from source (leaves) to sink (storage organs or growing regions).
     • Mechanism: Pressure flow hypothesis explains the movement of food due to turgor pressure differences.

6. Mineral Nutrition and Transport

   • Plants absorb minerals from the soil in ionic form.
   • Active and passive transport mechanisms help in nutrient uptake and distribution.

7. Guttation and Root Pressure

   • Guttation: Loss of water droplets from the edges of leaves through hydathodes.
   • Root Pressure: Positive pressure generated in roots due to active ion accumulation.

Conclusion

Transport in plants is a vital process for their survival and functioning. It ensures the efficient movement of water, minerals, and nutrients to sustain growth, photosynthesis, and metabolism. Understanding these transport mechanisms provides insights into how plants adapt to their environment and manage their internal systems effectively.

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