Govt. Exams
Entrance Exams
A pollen grain is the mature male gametophyte consisting of two cells: vegetative and generative cell.
Strawberry reproduces vegetatively through runners (stolons) that develop new plants at nodes.
The anther is the male reproductive organ that produces and contains pollen grains.
Meiosis in a megasporocyte produces four megaspores, though typically only one survives (functional megaspore).
Asexual reproduction produces genetically identical clones of the parent plant without involving meiosis or gamete fusion.
Transpiration pull is the tension/negative pressure developed in xylem vessels due to continuous water loss (transpiration) from leaves. This creates a suction force that pulls water upward from roots. It can occur both day and night through lenticels and cuticles, though primarily during day.
White patches result from chloroplasts lacking chlorophyll or being non-functional, typically due to mutations in chloroplast DNA (maternal inheritance). Green patches have functional chloroplasts.
Phytochrome exists in two interconvertible forms (Pr and Pfr) and acts as a red/far-red light sensor, measuring day length for photoperiodic flowering responses.
Carotenoids absorb light energy in blue and green regions, transfer it to chlorophyll, and provide photoprotection by quenching singlet oxygen and excess excitation energy.
K+ accumulation in guard cells lowers the water potential, causing water influx and turgor increase, leading to stomatal opening. This is the primary mechanism.
