Reproduction in Plants

Flower

Reproductive structure of angiosperm Sporophyte – diploid

Produces haploid spores Mitosis produces haploid gametophyte

Two types of spores Microspores male gametophytes pollen grain Megaspores female gametophytes embryo sac

Fertilization zygote becomes embryo within ovule seed

Ovary becomes a fruit

Flower parts

sepal – green, protects bud Petal – specific to pollinator, wind pollination may

not have flowers Stamen – male

anther -pollen grains produced here from microspores filament

Carpel – female Stigma – sticky knob Style - stalk Ovary – base, contains ovules

Ovary

Contains ovules, which produces megaspores female gametophytes

Complete flower – contains sepal, petal, carpel and stamen

Perfect flower – contains stamen and carpel – bisexual, monoecious

Life cycle of flowering plants

Sporophyte produces haploid spores grow and develop into haploid gametophytes mitosis gametes

Heterosporous – produce micro and megaspores Microspores – produce sperm bearing

pollen grains (male gametophytes) Megaspores – produce egg bearing

embryo sacs (female gametophytes)

Life cycle fig. 28.5

Microsporocyte (microspore mother cell) undergoes meiosis 4 haploid microspores pollen grains

Megasporocyte (megaspore mother cell) undergoes meiosis 4 haploid megaspores 1 embryo sac

Pollination

transfer of pollen from an anther to the stigma of a carpel

Pollen tube is formed when pollen lands on stigma

Double fertilization – 1 sperm nucleus unites with the egg nucleus 2n zygote mitosis to form embryo Other sperm nucleus unties with polar nuclei of

central cell and forms 3n endosperm cell Endosperm nourishes embryo and seedling

during development