During the rainy season, wooden doors are often difficult to open or close because of ?

During the rainy season, it is common for wooden doors and windows to become difficult to open or close. This happens because of a physical phenomenon called imbibition. Imbibition is the process by which materials, especially colloids like wood, seeds, or gums, absorb water and swell in volume without undergoing a chemical change. Wood contains cellulose, a hydrophilic material that attracts water molecules. When the surrounding air becomes humid or when wood comes into direct contact with water, it absorbs water and expands.

This expansion increases the thickness and volume of the wooden door, causing it to fit tightly within the frame, which makes opening or closing difficult. Once the rainy season is over and humidity decreases, the wood gradually loses water and shrinks back to its original size.

Other options in the MCQ are incorrect:

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  Plasmolysis is the loss of water from plant cells leading to cell shrinkage and is not related to wooden doors.

  
  


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  Osmosis is the movement of water across a semipermeable membrane, which does not directly explain the swelling of wood.

  
  


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  Diffusion refers to the movement of molecules from higher concentration to lower concentration, which is unrelated to the expansion of doors.

  
  

Understanding imbibition is important in biology and daily life. It explains not only the swelling of wooden doors but also the absorption of water by seeds during germination, the swelling of plant gums, and the hydration of other colloidal materials. It demonstrates a basic physical property of water absorption and shows how natural materials interact with water.

This concept highlights the practical relevance of plant physiology and water absorption in everyday life. Knowing about imbibition helps students connect classroom theory with real-world observations, such as why doors and wooden furniture behave differently in humid environments.