Entrance Exams
Govt. Exams
At the hypocotyl, the root's endarch xylem (with protoxylem toward center) transitions to the shoot's exarch xylem (protoxylem toward periphery).
Stomatal crypts are sunken regions containing stomata that create a microenvironment reducing transpiration by trapping moist air.
Sieve plates contain pores that maintain cytoplasmic continuity between adjacent sieve tube elements, facilitating the transport of photosynthates.
The cork cambium (phellogen) is the meristematic layer that divides to produce cork cells outwardly and phelloderm inwardly.
Aerenchyma—parenchymatous tissue with large intercellular air spaces—provides buoyancy and oxygen transport in aquatic plants.
Annual rings form due to seasonal variations in xylem formation: large earlywood cells (spring) and smaller latewood cells (summer), creating visible rings.
Collenchyma has unequally thickened primary cell walls, usually at corners, providing mechanical support while remaining flexible. It retains living protoplasm.
Bulliform cells are large, vacuolated cells on the adaxial surface of monocot leaves that control leaf rolling to reduce water loss during drought.
The phellogen typically develops from cortical or endodermal cells in dicot stems, occasionally from the epidermis, replacing the original epidermis.
Palisade parenchyma consists of elongated cells arranged perpendicular to the leaf surface, maximizing light capture for photosynthesis.