Phloem


 
 
Concept Explanation
 

Phloem

Tissues are the group of cells that perform a particular function. Phloem is a type of permanent tissue.

Phloem:

Phloem too is a complex tissue made up of four types of cells, or elements— sieve tubes, companion cells, phloem fibres and phloem parenchyma. It is not necessary for the phloem to contain all four types of cells. Phloem cells are living cells (except phloem fibres) which help transport food from leaves to the storage organs and growing regions of the plant.

  • Sieve tubes are a collection of thin-walled elongated cells placed end to end to form slender, tubular structures. The walls between the cells have pores, much like a sieve, and are called sieve plates. That is how the cytoplasm of the cells is continuous, passing through the pores from one cell to the next. In the same way food is transported through these tubes. The cells, or elements as they are called, do not have nuclei.
  • Companion cells generally occur with sieve tubes and are connected to them through pores. These are small cells with dense cytoplasm and a large, elongated nucleus. These cells are not present in all plants. For instance, ferns and pines do not have them.
  • Phloem Fibres are dead sclerenchyma cells. All plants do not have them.
  • Phloem Parenchyma Cells also form a part of the phloem. When present, they store food and help to conduct it.
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    Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    Which of the following are correct ?

    (a) The sieve tubes, companion cells, phloem fibres and phloem parenchyma are present in phloem .

    (b) Phloem Fibres are dead sclerenchyma cells. All plants do not have them.

    (c) Phloem Parenchyma Cells also form a part of the phloem. When present, they store food and help to conduct it .

                                               

    Right Option : D
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    Explanation
    Question : 2

    Phloem fibres are dead _____________________  cells.

    Right Option : A
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    Explanation
    Question : 3

    Phloem cells are living cells which help ____________________  to the storage organs and growing regions of the plant.

    Right Option : B
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    Explanation
     
     
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