Question

Sugar transport elements of gymnosperms and pteridophytes are
(a) Sieve cells
(b) Sieve elements
(c) Sieve tubes
(d) Sieve tube elements

Answer 1

Hint: They are the long, elongated form side to side cells found in the phloem of gymnosperms and ferns, having pores but lacking sieve plates. These cells have a major function in food conduction in the phloem system.

Complete answer:
Sieve cells are slender, that form a conducting system of the phloem but do not constitute an element of a sieve tube, these form relatively unspecialized sieve areas, especially in the tapering ends of the cells that overlap those of other sieve cells. 
Sieve cells are usually related to gymnosperms due to the fact that the phloem of angiosperms contain the more derived sieve- tube members and companion cells with a narrower diameter and are slightly more elongated when compared to sieve- tube members. 
Sieve cells are linked to albuminous cells, which are starch deficient and play a role similar to companion cells of sieve tube elements, which differentiates them from the phloem parenchyma.
So, the correct answer is ‘(a) Sieve cells’.

Additional Information:
- Phloem is a living plant tissue that plays a crucial role in the transport of soluble compounds which are derivatives of photosynthetic activity, mainly sucrose, to the target area where energy is needed to be utilized or stored.
- Phloem carries the food prepared in the leaves to other organs like stem, roots, fruits, buds, etc.
- Xylem carries the water and other minerals from the roots of the plant to other areas where it is needed like the leaves, flowers, stem, etc.
- The phloem consists of several other kinds of cells that constitute the phloem parenchyma cells, sieve elements, fiber, scleroids.

Note: Pteridophytes are also referred to as the botanical snakes because of their evolution from bryophytes (the amphibians of the plant kingdom) . Because the pteridophytes are seedless and flowerless, they are also called Cryptograms which suggests that their mode of reproduction is hidden.