Govt. Exams
Entrance Exams
Transpiration increases with decrease in humidity as the vapor pressure gradient between leaf and atmosphere increases.
In C4 plants, CO2 combines with PEP to form oxaloacetate (4-carbon compound) in the mesophyll cells, unlike C3 plants where 3-PGA is formed.
P680 is a special chlorophyll a molecule in the reaction center of PSII that absorbs light at 680 nm wavelength.
Red light (600-700 nm) is most effectively used in photosynthesis, followed by blue light. Green light is poorly absorbed.
The scattered distribution of vascular bundles in monocots (polystelic arrangement) means that damage to one bundle doesn't severely compromise the entire plant's transport system, unlike the concentric arrangement in dicots where the vascular cylinder is a continuous ring. This provides functional redundancy and allows monocots like grasses to survive grazing and mechanical damage.
Lenticels are porous structures in the periderm (cork) that allow gaseous exchange (respiration) to occur in woody stems where stomata are absent.
Mesophytes have higher stomatal density as water is readily available, while xerophytes have lower stomatal density as an adaptation to reduce water loss.
The pericycle is the outermost layer of the stele (inside endodermis) and gives rise to lateral roots and the vascular cambium during secondary growth.
Hydrophytes living in aquatic environments have reduced xylem development as water provides mechanical support (buoyancy) to the plant body.
Xylem parenchyma cells remain alive at maturity and are involved in storage and lateral transport, unlike tracheids and vessels which are dead at maturity.
