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Chapter 31.1. Reproductive Structures of Flowering Plants. AP Biology Spring 2011. Floral Structure and Function. Flowers form on a modified branch of the sporophyte when master genes in the apical meristem are turned on . Floral Structure and Function.
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Chapter 31.1 Reproductive Structures of Flowering Plants AP Biology Spring 2011
Floral Structure and Function Flowers form on a modified branch of the sporophyte when master genes in the apical meristem are turned on
Floral Structure and Function Flower parts are arranged in whorls of modified leaves on the end of the receptacle
Floral Structure and Function Sepals: outermost green, leaf-like parts arranged in a ring called the calyx Petals: the coloured parts located between the reproductive structures and the sepals, arranged in a ring called the corolla
Floral Structure and Function Stamens: male parts, slender stalk (filament) capped with an anther, inside which pollen sacs enclose pollen grains Carpels: female parts, vessel shaped structures with an expanded lower ovary (with ovules), slender column (style), and an upper surface (stigma) for pollen landing
Floral Structure and Function • Meiosis of cells within flowers produces haploid spores • Microspores in the anther • Megaspore in the ovule • They then undergo mitosis to produce the haploid gametophytes that ultimately become the egg or sperm
Floral Structure and Function The egg and the sperm fuse to form the diploid zygote As the zygote develops into a plant, the seed is formed
Diversity in Flower Structure Complete flowers: have all four whorls (sepals, petals, stamens, and carpels) Incomplete flowers: are missing one or more whorls
Diversity in Flower Structure Perfect flowers: have both stamens and carpel (both sexes on one flower) Imperfect flowers: produce either stamens or carpels and are known as either “male” or “female” flowers