Five Known Plant Hormones and One Suspected Plant Hormone

Five Known Plant Hormones and One Suspected Plant Hormone -...

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Bi Sci 001 Wednesday, February 17, 1999 Announcements: Lecture notes: Test on Friday How Can plants Grow So Fast? 1. Water entering the central vacuole at a higher rate, stretches the cell and forces it to keep adding to the cell wall. As cellulose and other support molecules are added, the cell wall becomes so rigid that it cannot grow any more. The pressure inside makes the cell very firm. This is called Turgor. 2. A lot of hormones. Five Known Plant Hormones and One Suspected Plant Hormone Auxins : these cause elongation of stem cells and elongation of the coleptyle (the first shoot out of the seed ) Gibberellins : these cause stem elongation and help break dormancy of seeds and buds. Cytokinins : increase cell division and retard leaf aging. Abscisic acid : promotes closure of stomata, may trigger dormancy in leaves and seeds. Ethylene : promotes fruit ripening and abscission (leaf drop) *Florigan : proposed - promotes flowering Plant Reproduction Reminder: Sporophyte : Diploid (2n) Spore producing body. (what we think of as the plant) Gametophyte : Haploid (1n) Gamete producing body Male-pollen grains Female-
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embryo sacs in ovules. Angiosperm gametophytes are in the flower.
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Five Known Plant Hormones and One Suspected Plant Hormone -...

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