(a) A liverwort plant is unable to complete its life cycle in a dry environment.
(b) Number of male gametes produced is much more than the female gametes produced.
(c) Organisms exhibiting external fertilization show great synchrony between the sexes and release a large number of gametes into surrounding medium.
(a) Liverworts require water to complete their life cycle through sexual reproduction.They need water as medium of gamete transfer for fertilization.
(b) Male gametes are transferred through water in several simple plants algae bryophytes and pteridophytes. A large number of male gametes , however , fail to reach the female gametes. To compensate this loss of male gametes during transport, the number of male gametes produced is several thousand times the number of female gametes produced.
(c) To enhance the chances of syngamy.