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Explain the term Gymnosperms. |
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Answer» • Medium sized trees and shrubs. • Have naked seeds as the ovules are not enclosed by any ovary wall and remain exposed. • Male cone has microsporophylls which bear microsporangia having microspores which develop into reduced gametophyte called pollen grain. • Female cone has megasporophylls which bear megasporongia having megaspores which are enclosed within the megasporangium (Nucellus). One megaspore develops into female gametophyte bearing two or more archegonia. • Pollen grains carried in air currents reach ovules, form pollen tube which reach archegonia and release male gametes which fertilise egg cell and form zygote which produce embryos. Ovules develop into seeds which are not covered. e.g. Cycas, Pinus ,Cedrusetc. |
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