Entrance Exams
Govt. Exams
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.
Succulent plants like cacti have specialized thin-walled parenchymatous tissues that store water. The waxy cuticle reduces water loss, not parenchyma.
Dicot roots typically show tetrarch arrangement (4 xylem groups), while monocot roots show polyarch arrangement. Triarch is less common in roots.
The middle lamella is composed mainly of pectin and calcium pectate, which acts as a cement holding adjacent cells together.
Xylem transports water and minerals (inorganic nutrients) from roots to all parts of the plant in an upward direction.
The endodermis contains Casparian strips—bands of suberin and lignin that prevent lateral movement of water and minerals, forcing them through the cell.
Monocot stems have scattered vascular bundles distributed throughout the ground tissue, whereas dicot stems have bundles arranged in a ring.