When and
where does reduction division take place in the life cycle of a
liverwort, a moss, a fern, a gymnosperm and an angiosperm?
When and where does reduction division take place in the life cycle of a liverwort, a moss, a fern, a gymnosperm and an angiosperm?
Liverwort
– In liverworts, the main
plant-body is haploid (gametophytic). It bears the male and female
sex organs which produce gametes. These gametes fuse to form a
zygote. The zygote develops on the gametophytic plant-body to form a
sporophyte. The sporophyte is differentiated into the foot, seta, and
capsule. Many haploid spores are produced as a result of the
reduction division taking place inside the capsule.
Moss
– In mosses, the primary
protonema (developed in the first stage) develops into the secondary
protonema. Both these stages are haploid or gametophytic. The
secondary protonema bears the sex organs which produce gametes. These
gametes fuse to form a zygote. The zygote develops into a sporophyte.
Many spores are formed as a result of the reduction division taking
place in the capsule of this sporophyte.
Fern
– In ferns, the main plant-body
is sporophytic. Its leaves are known as sporophylls and these bear
the sporangia. Reduction division takes place in these sporangia,
thereby producing many spores.
Gymnosperm
– In gymnosperms, the main
plant-body is sporophytic. They bear two types of leaves –
microsporophylls and megasporophylls. Reduction division takes place
in the microsporangia present on the microsporophylls (producing
pollen grains) and on the megasporangia present on the
megasporophylls (producing megaspores).
Angiosperm
– In angiosperms, the main
plant-body is sporophytic and bears flowers. The male sex organ in
the flower is the stamen, while the female sex organ is the pistil.
Reduction division takes place in the anthers of the stamen
(producing haploid pollen grains) and in the ovary of the pistil
(producing eggs).
Liverwort – In liverworts, the main plant-body is haploid (gametophytic). It bears the male and female sex organs which produce gametes. These gametes fuse to form a zygote. The zygote develops on the gametophytic plant-body to form a sporophyte. The sporophyte is differentiated into the foot, seta, and capsule. Many haploid spores are produced as a result of the reduction division taking place inside the capsule.
Moss – In mosses, the primary protonema (developed in the first stage) develops into the secondary protonema. Both these stages are haploid or gametophytic. The secondary protonema bears the sex organs which produce gametes. These gametes fuse to form a zygote. The zygote develops into a sporophyte. Many spores are formed as a result of the reduction division taking place in the capsule of this sporophyte.
Fern – In ferns, the main plant-body is sporophytic. Its leaves are known as sporophylls and these bear the sporangia. Reduction division takes place in these sporangia, thereby producing many spores.
Gymnosperm – In gymnosperms, the main plant-body is sporophytic. They bear two types of leaves – microsporophylls and megasporophylls. Reduction division takes place in the microsporangia present on the microsporophylls (producing pollen grains) and on the megasporangia present on the megasporophylls (producing megaspores).
Angiosperm – In angiosperms, the main plant-body is sporophytic and bears flowers. The male sex organ in the flower is the stamen, while the female sex organ is the pistil. Reduction division takes place in the anthers of the stamen (producing haploid pollen grains) and in the ovary of the pistil (producing eggs).
