Reproduction in Angiosperms

Reproduction in Angiosperms Flower Part Function Sepals Support the petals and the rest of the flower petals Attract pollinators by having pretty colours and scents anther Pollen is produced and located here filament Attaches the anther to the rest of the plant, makes pollen available to pollinator stigma The top of the pistil, where the pollen enters Style Holds up the pistil, path pollen takes to ovary Ovary Where the “eggs” are, where fertilization takes place to form a zygote.

Reproduction in Angiosperms Pollination Fertilization When pollen is carried to plant by pollinators Gametophyte generation: haploid Methods of Pollination: wind, water, pollinators (insects, animals), artificial pollination Types of Pollination: CROSS POLLINATION: across two different plants – creates genetic diversity of plants. SELF POLLINATION: within the same plant, No variation, increases harmful mutations, continuation of a specific species. Sporophyte generation: diploids Steps: after pollen is caught by the stigma, it goes down the pollen tube within the style, into the ovules. The haploid cells of pollen fertilize the ovule haploids to produce a zygote.

Reproduction in Angiosperms Seed Part Function testa Protect the embryo cotyledons Food for the embryo Micropyle Attaches the embryo to food source, where the pollen once entered Embryo root/shoot/radicle The actual plant growth hilum micropyle

Reproduction in Angiosperms Conditions for Seed germination 1. Warm temperatures: allows chemical reactions in seed to occur to start growth. Optimal temperature needed – too hot will denature proteins, too cold will slow down progress. 2. Moisture: not provided by the cotyledon, softens testa to allow embryo to grow hilum micropyle

Reproduction in Angiosperms Plant Type Flowering and light Examples Long Day plants Bloom when days are longests and nights are shortest Radishes, spinach, and lettuce Short Day Plants Bloom in spring, late summer, and autum when days are shorter Poinsettias, chrysantheumums, and asters Day-neutral plants Flower without regard to day length Roses, dandilions and tomatoes

Reproduction in Angiosperms 660 nm red light Growth Response (promoted or inhibited) Pr Rapid reaction Pfr 730 nm red light Pfr reverts to Pr in the dark very slowly