Q.
Assertion In Fritillaria, the embryo sac is described as tetrasporic type. Reason In Fritillaria, four megaspore mother cells are involved in the formation of an embryo sac.
In Fritllaria, tetrasporic type embryo sac, four megaspores are formed after meiosis division in MMC in which one migrates towards micropylar pole and three migrate towards the chalazal pole where they become fused and form a triploid nuclei. Two successive mitoric division operates in both these two nuclei, which result four cells at micropylar pole (haploid) and four cells are formed on chalazal pole (each triploid). One (haploid) nuclei from micropylar pole and one (triploid) nuclei from chalazal pole migrate towards the centre, where they are organized into the central cell. Thus, central cell contains four nuclei. Three cells are arranged into egg apparatus, at micropylar pole. Three cells are organised into antipodal cells (each with triploid nucleus) at chalazal pole.