Reproduction of Seed Plants

Alternation of Generation All plants life cycle alternates Diploid Sporophyte  Haploid Gametophyte Sporophyte = Entire Plant Gametophyte = hidden in plant –Gymnosperm gametophyte = inside cones –Angiosperm gametophyte = inside flower

Gymnosperm vs Angiosperm Produce Cones where reproduction occurs Pollen Cones (males) Seed Cones (females) Ovules = meiosis makes haploid female gametophytes Produce Flowers where reproduction occur Sepals = protect flower while developing Petals = colored; attract insects Stamen –Filament & Anther (male) Carpel –Ovary, Style, Stigma (female)

Male StructureFemale Structure

Life Cycle of Gymnosperm Takes 2 years to complete Wind carries pollen (male) Lands on seed cones & pollinates Pollen Tube forms & allows pollen to reach female gametophyte New Sporophyte Plant Formed!

Life Cycle of Angiosperm Anther = produces male gametophytes Ovary = produces female gametophytes Stigma = sticky portion; pollen attaches to it Seeds develop inside protective structures Pollinated by wind or animal –Animal pollination WORKS BEST!!!! –Animals transfer pollen from one flower to another

Double Fertilization Two fertilizations occur between male & female gametophytes: –One forms into EMBRYO –Second forms into ENDOSPERM Endosperm nourishes the seedling as it grows

Fruit Development Angiosperm seeds mature –Ovary walls thicken to form a fruit that hold seeds Fruit = any seed surrounded by embryo wall –Includes: Apples, Grapes, Strawberried –Includes Vegetables: peas, corn, beans, rice

Seed Dispersal Animals: eat fruits and poop out seeds Wind: light-weight seeds can be carried Water: seeds can float allowing water transport

Dormancy & Germination Dormancy = embryo is alive, but doesn’t grow –Caused by environment not being good enough –Temperature and moisture needs to be ideal Germination = early growth of plant embryo –Monocots = single cotyledon beneath ground –Dicots = two cotyledons grow above ground

Plant Responses Plants respond to different factors: –Phototropism = response to light Plants grow toward light –Gravitropism = response to gravity Plants grow against gravity –Thigmotropism = response to touch Plants react to touch Vines

Hormones To respond to stimuli, plants use hormones AUXINS –Most important –Makes shaded area of plant grow more –Makes area affected by gravity grow more Cytokinins –Stimulate cell division & dormancy of seeds Gibberellins –Increases size of stems & fruits

Evolve to Environment Water plants can hold more gases Desert plants can hold more water Marine plants can tolerate salt Carnivorous Plants: –Some can digest organisms –Some are parasitic on other plants