Plant Kingdom Test - 11

Bryophytes are called as amphibians of plant kingdom as they can grow in both land and water. Water is essential for completion of life cycle as they release antherozoids into water where they come in contact with archegonium to produce zygote.

The yellow or brown spots which have sporangia in fern are called sori. Spores are produced inside these sporangia to produce haploid gametophyte.

In Gymnosperms, cross pollination is mainly accompanied by wind. The pollen grains are produced in large quantity and generally lighter.

Adaptation is essential for the survival of living  organism. The greatest extent of adaption in various environmental conditions is found in Angiosperms. Angiosperms are found in all kind of environment and altitudes.

The pollen tubes enter the embryo-sac where two male gametes are discharged. One of the male gametes fuses with the egg cell to form a zygote (syngamy). The other male gamete fuses with the diploid secondary nucleus to produce the triploid primary endosperm nucleus (PEN) .Because of the involvement of two fusions, this event is termed as double fertilisation,

In dicots, each embryo-sac consists of egg apparatus( ovum and two synergids )located at micropylar end , three antipodal cells located at chalazal end and two polar nuclei at the center.

Pinus belongs to division gymnosperms. In gymnosperms seeds are formed but not inside the fruit. They are also called as plants with naked seeds.

Generally seeds are formed inside the fruits. But in banana viable seeds are not present .It is  a parthenocarpic fruit.

Gnetum differ from Cycas or Pinus in presence of xylem vessels. Vessels are absent in Gymnosperms but present in angiosperms. This features shows affinities with angiosperms to Gnetum.

Cycas produces top shaped multinucleate male gametes and mature seeds with one embryo having two cotyledons. Although, male and female gametes are generally uninucleate in gymnosperms.