The major function of sieve tubes in plants is

The diagram given below is a transverse section of

Colonization of land by plants was associated with the evolution of structures of obtain water and to minimize water loss. Which of the following adaptation are associated with the later?

i. Development of epidermis with waxy cuticle.
ii. Development of stomata with elaborate opening and closing mechanism.
iii. Development of bark on old stem and roots.

Reason : Respiration occurs by means of air chambers in submerged plants.

Reason : Spongy mesophyll contains less chloroplasts than palisade mesophyll cells.