Name: Structure of the Leaf
Uploaded: 2019-07-19
Duration: 2 min 35 s
Description: Leaves are the food factories of the plant. Chlorophyll in leaves makes food for the plant using carbon dioxide, water and sunlight. Explore this video.

Question

What are sieve tubes? Explain.

Accepted Answer

Sieve cells are specialised cells, which are important for the functions of phloem. Sieve tubes are present only in angiosperms. It functions as a temporary cell wall within a plant in response to the stimuli such as stress or any other condition of damage. They are long tube-like structures which are arranged side by side in an elongated manner. They have sieve plates which are perforated for the transportation of food.

In a mature sieve tube, the nucleus is absent. They have thin-walled cells attached to the sieve tubes, which are special parenchyma cells connected with sieve tubes through lateral pits present in the walls. These cells are called as companion cells and are multinucleated having a cytoplasmic connection with sieve tubes. They maintain the pressure gradient in the sieve tubes. The conduction of food takes place through cytoplasmic strands.

What are sieve tubes? Explain.

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