BIOL108 Lecture 13: BIOL 108 - Lecture #13 - Gymnosperms

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Lien Luong

Document Summary

Seed: **wrapped by sporophyte, an embryo in gametophyte tissue*, ranges in size, variation occurs depending on the gametophyte food. Gymnosperm life cycle: sporophyte (2n) ==> mature tree, sporangia: found on sporophylls (scale-like leaves) on cones (clusters, heterospory: produce both megasporangia (female) and microsporangia (male) Can be on the same tree or on different tree: pollination occurs by wind. Air bladders on pollen helps with that: seed also disperses by wind. Pollination: drastic change in evolutionary strategy, occurs when pollen meets up with the ovules. Pollen tube spews out sperm into ovule, the female gametophyte: non-seed. Sperm needs water to swim its way through: seed. Male gametophyte chills inside the pollen grain. Greater distance = great: food supply for fertilized egg derives from gametophyte. Seeds: dispersal stage (air, water, animals, animals spread the seeds by eating fruit, but not the seed, and it is pooped out. Whereas in non-seed plants, spore is travelling stage: tiny embryo protected.