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Doctors Medicines MCQs Q&A

  1. Cell membrane
  2. Cell wall
  3. Mitochondria
  4. Lysosomes
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1 Answers

Option 2 : Cell wall

The correct answer is Cell Wall.

  • A cell wall is a rigid layer of polysaccharides lying outside the plasma membrane of the cells of plants, fungi, and bacteria.
  • In the algae and higher plants, it consists mainly of cellulose.

Plant cell wall:

  • The plant cell wall is made up of cellulose and pectin.
  • It provides a structural framework to support the growth of plants.
  • The cell wall also acts as the first line of defence against pathogens.
  • A plant cell consists of a cell wall for structural rigidity and tough environmental conditions. The cell wall consists of three layers. 
    • The primary cell wall
    • secondary cell wall
    • middle lamella.
  • The primary wall is composed of up to 50% Hemicellulose, cellulose 25%, and other smaller amounts of pectic substances, non-polysaccharides, fats, and proteins. The primary wall is the cellulose-containing layer laid down by cells that are dividing and growing.
  • The secondary wall is composed of Lignin. Secondary cell walls provide additional protection to cells and rigidity and strength to the larger plant. Lignin makes the wall thick and rigid.
  • Middle lamella is composed of Pectin. The middle lamella serves as a cementing layer between the primary walls of adjacent cells. The two cells can be separated from each other by the dissolution of the middle lamella by proteolytic enzymes.

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