Govt. Exams
Entrance Exams
The tapetum is derived from the innermost layer of the anther wall, which develops from the middle layers. It undergoes mitotic divisions to form the nutritive tissue for pollen development.
The endosperm is triploid (3n) because it develops from the primary endosperm nucleus, which is formed by fusion of two polar nuclei (2n) and one sperm nucleus (n).
The generative nucleus lies within the vegetative (or tube) cell in mature pollen. The vegetative cell also contains a large vacuole.
The fusion of two polar nuclei (2n) with one sperm nucleus (n) produces the primary endosperm nucleus (3n), which develops into the endosperm tissue.
The nucellus is the nutritive tissue surrounding the megasporangium that provides nutrients to the developing megaspore and female gametophyte.
Apomixis is asexual reproduction through seeds where the embryo develops from an unfertilized egg cell (apomeiotic parthenogenesis) or other cells without meiosis or fertilization.
The tapetum is a nutritive tissue layer that provides nutrients to developing microspores and pollen grains through absorption and transfer.
In microsporogenesis, all four microspores produced from meiosis are typically functional. In megasporogenesis, usually three of the four megaspores degenerate, leaving only one functional megaspore.
In Bryophyllum, small adventitious buds form at the margins of leaves, which can develop into new plants when they fall to the soil.
The mature female gametophyte (7-celled, 8-nucleate) contains: 1 egg cell, 2 synergids, 2 polar nuclei (in central cell), and 3 antipodal cells = 8 nuclei total.
