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Question
A narrow thin-walled cell with large nucleus and lying on the side of sieve tube is absent in
A narrow thin-walled cell with large nucleus and lying on the side of sieve tube is absent in
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Solution
The correct option is C Both B and C
The phloem vessels in angiosperms are made up of sieve tubes and companion cells. While sieve tubes are long tubes, which are made by the end to end union of a large number of cells, the companion cells are narrow, elongated and thin-walled cells that lie on the sides of sieve tube cells. The companion cells contain a nucleus, which helps to control the functioning of sieve tube cells.
In phloem, sieve cells are present, companion cells and sieve tubes are absent in pteridophytes and the gymnosperms. These companion cells are present only in the angiosperms.Thus, the correct answer is option D.
The phloem vessels in angiosperms are made up of sieve tubes and companion cells. While sieve tubes are long tubes, which are made by the end to end union of a large number of cells, the companion cells are narrow, elongated and thin-walled cells that lie on the sides of sieve tube cells. The companion cells contain a nucleus, which helps to control the functioning of sieve tube cells.
In phloem, sieve cells are present, companion cells and sieve tubes are absent in pteridophytes and the gymnosperms. These companion cells are present only in the angiosperms.
Thus, the correct answer is option D.
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