Entrance Exams
Govt. Exams
Xylem is a vascular tissue that transports water and minerals from roots to shoots through tracheids and vessels.
In roots, protoxylem is toward the center and metaxylem toward periphery, defining the endarch arrangement unique to roots among vascular organs.
Gymnosperm wood consists mainly of tracheids without true vessels, making it different from dicot wood which has both vessels and tracheids.
C4 plants have well-developed chloroplasts in bundle sheath cells for the Calvin cycle, while C3 plants have minimal chloroplasts in bundle sheaths.
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.