Question

Heterospory is a development towards seed habit Do you agree?

Answer 1

• 1.Yes Production of two types of spores by a plant is called heterospory. Eg : Selaginella.
• 2.Large spores are called megaspores and small spores are called microspores. Megaspore → Female gametophyte →Archegonia →egg. Microspore →Male gemetophyte →Antheridia →Antherozoids.
• 3.The two gametophytes remain protected inside the respective spores in the sporophytic phase.
• Microspores are dispersed by wind and reach the Megaspore. The Antherozoid fuses with the egg toform zygote.
• Thus the gametophytic generation is completed in the sporophyte plant itself. Only a er zygoteformation the female gametophyte is shed from the sporophyte.
• This is a basic requisite for seed habit.
• Distinguish apogamy and apospory.
• 1.Apogamy - A type of reproduction occuring in some ferns in which the sporophyte develops from the gametophyte without fusion of gametes.
• 2.Apospory - The development of a gametophyte directly from a sporophyte without the occurrence of mieosis or spore formation.
• Both apogamy and apospory are seen in pteridophytes.
• Why do mosses thrive only in moist habitat?
• Mosses (bryophytes) are non-vascular land plants of moist habitat that grow densely together ando en form green carpets or mats on damp soil.
• It is because in the absence of roots, thallus absorbs water and minerals directly from ground oratmosphere. Hence, they can thrive only on moist places.