Question

Give information about reproduction in gymnosperms?

Answer 1

Hint:Gymnosperms are woody plants that produce bare seeds. The pollen grain is transferred by wind to the ovule where the pollen tube grows towards the archegonia of the ovule and discharges their contents.

Complete answer:
In all living gymnosperm species, the recognizable portion of the plant is the sporophyte or asexual generation rather than the gametophyte or sexual generation. The male and female gametophytes are borne on structures called sporophylls.

In most gymnosperms, male pollen cones, known as microstrobili, have reduced leaves called microsporophylls. Microspores grow into a male gametophytic generation that is heavily reduced and limited to a limited number of cells. This reduced gametophyte is known as pollen grains. The production of pollen grains takes place within the microsporangia. Female cones, called megastrobili, can be found on the same plant that carries microstrobili or on different plants. Ovules are borne on megasporophylls and may be crowded together to form female cones. The mother cell megaspore divides meiotically to form four megaspores. One of the megaspore undergoes mitosis to form a female gametophyte. As the amount of free nucleus multiplies, the megasporangium and megaspore walls extend. The ovule is ready to be fertilised at this point. The pollen grain must be transported to the female gametophyte for fertilisation. The fertilised egg undergoes mitosis to begin the development of a new generation of sporophytes, the multicellular embryo of the seed.

Note:In gymnosperms, when the nucleus of the two sperm enters the egg cell, one nucleus dies and the other unites with the egg nucleus to form the diploid zygote.