Evolution of Alternation of Generations Flowering Plant Reproduction Bryophyte gametophyte dominant sporophyte small dependent Seedless vascular gametophyte small dependent sporophyte dominant Gymno angiosperms gametophyte dependent sporophyte dominant Flower structure Flower Variation Sepals petals stamen carpel o Anther sporangia produces microspores n o Ovary containing ovules All evolved from leaf like structures Complete all 4 Incomplete controlled by level genes ABCE Perfect stamen and carpels Imperfect either Symmetry bilateral radial controlled by developmental gene Cycloidea gene Why have diverse flowers developed Monoecious stamenate carpellate flowers on one plants Dioecious stamenate carpellate flowers on separate plants Flower Variation Structure controlled by ABC genes Various of combinations of gene expression form different flower structure Genes that make the flower structure A sepal A B petal B C stamen C carpel FV placement of stamen and carpels Monoecious specimen corn Dioecious specimens holly has male and female plants Development of angiosperm gametophytes pollen Anther 4 sporangia 2n produces 4 microspores n Microspore pollen grain Microspore mitosis tube cell and generative cell sperm producing Pollen wall w sporopollenin Pollen coat causes allergies Development of angiosperm gametophyte egg Ovule sporangium 2n produces 4 megaspores n but only one survives Megaspore mitosis 8 nuclei 7 cells a cell with two nuclei causes double fertilization o Egg cell two nuclei of central cell Pollination and fertilization Mechanisms of pollination self compatible incompatible vs cross how pollen travels Double fertilization why is it double Pollen germination what happen when lands on stigma o Pollen tubes sperm cells undergo double fertilization A pollen tube brings two sperm cells to the female gametophyte 1 sperm n 1 egg zygote 2n 1 sperm n central cell 2n endosperm 3n Embryo Development Embryo cotyledons meristems shoot root Form in the seed Uses energy and nutrients from endosperm Dormancy dries out waits for environmental cue protected by a seed coat Temperature water fertilized by animal digestion causes plant seed to grow Seed germination Seed Structure Fruit Development What requires for germination Break dormancy rehydrate activates hormones then enzymes converts starch to sugars used for growth process used to produce maltose used in brewing Need to know 1st bud root stem nutrient source and protective covers Fruit ovaries or other floral parts classified based on developmental origin Simple from one carpel Aggregate many carpels strawberries Multiple multiple flowers carpels Why do diverse fruits develop Accessory produced by receptacle apple Aid in dispersal of seeds dry juicy do not release seeds Blackberries adapted for animal dispersal Quiz the 1st sperm fertilizes the egg the 2nd sperm fertilizes the central cell to produce the endosperm