Question

The dead element present in Phloem is

• A. Companion fibres
• B. Phloem fibres
• C. Phloem parenchyma
• D. Sieve tubes

Answer 1

The correct option is B

Phloem fibres

The correct option is Option B.

Explanation for the correct option:

Option A:

1. In vascular plants, the phloem is the living tissue that carries the soluble organic chemicals produced during photosynthesis.
2. Conducting cells, also known as sieve elements, parenchyma cells, which include both unspecialized and specialized companion cells or albuminous cells, and supportive cells like fibers and sclereids, makeup phloem tissue.
3. The primary phloem tissue that gives the plant stability, rigidity, and strength is called the sclerenchyma.
4. Both fibers and sclereids, two types of sclerenchyma, have thick secondary cell walls and are typically dead when they reach maturity.
5. The phloem fibers provide support to the tensile strength while permitting flexibility of the phloem.
6. They are elongated, narrow cells with a limited lumen and thick walls made of cellulose, hemicellulose, and lignin.
7. Sclereids are somewhat shorter, unusually shaped cells that contribute to the phloem's increased compression strength but limit its flexibility. They serve as defense mechanisms against herbivory.

Explanation for the incorrect options:

Option (A):

1. The companion cells are living, multi-mitochondrial cells that generate ATP as an energy source for active transport when moving sucrose throughout the plant.

Option (C):

1. The complex tissue phloem includes phloem parenchyma.
2. These elongated parenchymatous living cells store things like food, resins, latex, etc.
3. For the lateral conduction of food, it has a large number of plasmodesmata.

Option (D):

1. Living cells that do not have a nucleus make up the sieve tube cells, which are in charge of moving carbohydrates throughout the plant.

Final answer: The dead element present in phloem is phloem fibers.