Ch 30 - Plant Diversity II (1 slide per page)-1

allows for colonization of dry places 12 derived

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Unformatted text preview: 12 Derived Traits Ovules & Seeds Gymnosperm fertilization (A) (B) (C) (B1) ♀ gametophyte grows (C) Once egg fertilized, (inside megasporangium) (A) Megasporangium on sporophyte (2n) ovule called seed and produces egg (gamete)(n) produces megaspore (n) which in archegonium (gametangium) develops into ♀ gametophyte (n) Seed = Embryo (2n) (B2) Pollen grain, containing + Seed coat Initially, Ovule = Megasporangium (2n) ♂ gametophyte (n) in sporopollenin, + ♀ gametophyte (n) w/ megaspore (n) + integument comes to ♀ gametophyte (n) Later, Ovule = Megasporangium (food for embryo) and discharges sperm to fertilize egg w/ ♀ gametophyte + integument (sperm (n) + egg (n)= zygote (2n)) Figure 30.3 (Campbell et al) SEEDS 13 • Fertilized ovule develops into a seed • Contain an embryonic plant and a food supply (derived from ♀ gametophyte) • Can last long periods of dormancy. • Contain energy for germination – Until plant finds light and begins photosynthesis Female gametophyte embryo Pine seed (w/seed coats removed) Bean embryo after germination 14 Derived Traits of seed plants Pollen ~All seedless plants Single All seed plants Figure on page 613 (Campbell et al) 15 Derived Traits • Each microspore develops into a pollen grain Pollen • containing a male gametophyte • surrounded by a sporopollenin coat (makes it durable and waterproof) • Pollen transferred to ovule via various methods (e.g. wind or animals). i.e. it is water Independent! • If Pollen grain reaches the female gametophyte it germinates. • i.e. It gives rise to sperm and a pollen tube that breaks out of pollen grain, burrows towards ovule and discharges sperm Pollen grains are tiny (from 6 – 100 micrometers) Pollination 16 Movement of ♂ gametophyte, in pollen grain, to the ♀ gametophyte, in the ovule (prior to sperm development and fertilization) 1....
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