Question
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- From Biology: General-Biology
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- Due on May. 17, 2011
- Asked on May. 17, 2011 at 08:48:59AM
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Q:
Consider the changes that occurred both structurally and functionally as plants evolved to their modern forms. If you were to discover a totally new plant to you, what characteristics would you look for to determine which group of modern plants it belonged to?
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Evolution Of plants And Their Classification
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- Posted on May. 18, 2011 at 10:15:43AM
A:
Preview: ... ructures called strobili or cones ( Selaginella, Equisetum ). The sporangia produce spores by meiosis in spore mother cells. The spores germinate to give rise to inconspicuous, small but multicellular, free-living, mostly photosynthetic thalloid gametophytes called prothallus . These gametophytes require cool, damp, shady places to grow. Because of this specific restricted requirement and the need for water for fertilisation, the spread of living pteridophytes is limited and restricted to narrow geographical regions.
The gymnosperms ( gymnos : naked, sperma : seeds) are plants in which the ovules are not enclosed by any ovary wall and remain exposed, both before and after fertilisation. The seeds that develop post-fertilisation, are not covered, i.e., are naked. Gymnosperms include medium-sized trees or tall trees and shrubs (Figure 3.4). One of the gymnosperms, the giant redwood tree Sequoia is one of the tallest tree species. The roots are generally tap roots. The leaves in gymnosperms are well-adapted to withstand extremes of temperature, humidity and wind. The gymnosperms are heterosporous; they produce haploid microspores and megaspores.
Unlike the gymnosperms where the ovules are naked, in the angiosperms or flowering plants, the pollen grains and ovules ...
The full tutorial is about 931 words long plus attachments.
Evolution Of Plants.doc (30K)