Question

Major difference between phloem of angiosperms and gymnosperms is:
A) Sieve tube
B) Medullary rays
C) Bast fibre
D) Companion cells

Answer 1

Hint: Angiosperms are the plants that produce flowers. Angiosperms bear their seeds in fruit. Gymnosperms are a group of seed producing plants. Phloem is the tissue which is found in the vascular plants that transports the soluble organic compound to the parts of the plant where it is needed.

Complete answer:
The principal food conducting tissue in the vascular plants is phloem.Phloem is composed of conducting cells generally called sieve elements, parenchyma cells and supportive cells such as fibres and sclereids.
The phloem transports the sap.The sap is made by photosynthesis. It is a water based solution.The sieve element is referred to as sieve tube members in angiosperms and sieve cells in gymnosperms.In the sieve cells of gymnosperms there is no sieve plate. There are sieve pores that allow flow between adjacent cells.The sieve tube members of the angiosperms are wider than the sieve cells and have sieve plates that connect the ends of the adjacent cells.So the major difference between the sieve cells and sieve tube members is the sieve plates. The sieve plates are present in sieve tube members of the angiosperms but it is absent in the sieve cells of gymnosperms.So the major difference between the phloem of angiosperms and gymnosperms is sieve tube.

Hence the correct answer is option ‘A’.

Note: The sieve elements are the conducting cells which are responsible for transporting sugar throughout the plant. Food conducting cells in the gymnosperms are the sieve cells and in the angiosperms the food conducting cells are the sieve tube members.Bast fibres of phloem are long, supporting cells that provide tension strength. They are also present in the xylem.