Question

Which of the following statement is true? a)-All xylem cells are living except tracheids b)-All phloem cells are living except sieve tubes c)-All xylem cells are dead except xylem parenchyma d)-All phloem cells are dead cell except phloem fibres

Answer 1

Answer

Knowledge Required -

Xylem parenchyma is the only living tissue in xylem

Phloem sclerenchyma is the only dead and remaining all are living.

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Now checking the options -

$1^{st}$ option - All xylem cells are living except tracheids.

$\implies$This option is wrong because in the xylem only xylem parenchyma is living and other which are Tracheids , vessels and xylem sclerenchyma are dead.

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$2^{nd}$ option - All phloem cells are living except sieve tubes.

$\implies$This option is also incorrect because sieve tube is a living cell and only Phloem sclerenchyma is dead.

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$3^{rd}$ option - All xylem cells are dead except xylem parenchyma.

$\implies$This statement is correct because only xylem parenchyma is living and other all are dead.

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$4^{th}$ option - All phloem cells are dead cell except phloem fibres.

$\implies$This statement is incorrect because cells other than Phloem fibres are also living which are sieve tubes , companion cells , Phloem parenchyma.

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Thanks

Answer 2

Answer:

True statement

(c) All xylem cells are dead except xylem parenchyma.

Explanation:

a) Only xylem parenchyma is living in xylem and rest three tracheids, xylem vessels and xylem sclerenchyma are dead when mature. Xylem is responsible for transportation of water and is a bidirectional flow of water.

(b) In phloem, companion cells and sieve tubes are living cells whereas phloem sclerenchyma is dead. Phloem is responsible for transportation of food and is unidirectional flow of food.

(c) All xylem cells that are tracheids, xylem vessels and xylem sclerenchyma are dead whereas xylem parenchyma is living.

(d) Phloem fibres are the dead cells whereas companion cells and sieve tubes are living cells.

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