Govt 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.
Dark reactions (Calvin cycle) do not directly require light; they use ATP and NADPH produced from light reactions to fix CO2.
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.
Photosynthesis is the primary source of energy for plant cells as it converts light energy into chemical energy in the form of glucose.
The dorsiventral structure of dicot leaves is primarily established by differential light exposure (adaxial surface receives more direct light, promoting compact palisade development) combined with auxin gradients that influence cell differentiation patterns. The abaxial surface, receiving diffuse light and lower auxin concentration, develops the loosely packed spongy mesophyll with intercellular spaces for gas exchange.
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.
Root hairs are unicellular extensions of root epidermis that greatly increase absorptive surface area for water and mineral uptake.