SEXUAL REPRODUCTION IN SEED PLANTS

I. REPRODUCTIVE STRUCTURES OF SEED PLANTS

 1. Gametophyte is extremely small  2. Spores are not released- remain in tissue of sporophyte and develop into the gametophytes (male and female  A. Pollen grain- immature male gametophyte  B. Ovule- multicellular structure that is part of the sporophyte where the female gametophyte develops  3. Following fertilization, the ovule and its contents develop into a seed A. GYMNOSPERMS AND ANGIOSPERMS

 1. Wind and animals transport pollen grains to ovules  A. Pollination- transfer of pollen grains from the male reproductive structure to the female reproductive structure  B. Pollen Tube- tube that emerges from the pollen grain and grows to the ovule to pass sperm directly to the egg B. REPRODUCE SEXUALLY WITHOUT WATER

I. SEEDS

 1. Seeds contain the embryo of seed plants  2. Plant embryo is a new sporophyte  3. Seeds form from an ovule after the egg has been fertilized A. REVIEW

 1. Seed Coat- outer layers of the ovule that harden as the seed matures  A. offers protection  B. seeds germinate at different times, in different conditions, or must be exposed to light. The seed coat helps maintain the seed until that time  2. Endosperm- tissue that provided nutrients for the embryo  3. Cotyledon- seed leaf  A. transfer nutrients to the embryo  B. Monocots- 1 cotyledon, Dicots- 2 cotyledons B. SEED STRUCTURES

II. CONES

 A. Seed plants are the most successful plants  1. Angiosperms-ovules that are completely enclosed  2. Gymnosperms- ovules enclosed after pollination  B. Gametophyte of gymnosperm develops in cones  1. whorls of modified leaves  2. male pollen cones or female seed cones

 C. Pollination  1. pollen grains carried by wind to female cone  2. during pollination, female cones are open to expose ovules  3. pollen tube grows into the ovule  4. sperm enters ovule  5. seed cone closes after pollination and remains closed until the seeds mature, which can take up to two years

 1. The zygote and ovule develop into a seed which grows into a new sporophyte  2. An adult pine tree produces male and female cones  3. Meiosis occurs  4. Male and female spores form on the scales of the cones  5. Spores develop into male and female gametophytes  6. After pollination, sperm enter the ovule through a pollen tube and fertilization occurs D. LIFE CYCLE OF A CONIFER

IV. FLOWERS

 B. Structure of a Flower- arranged in 4 concentric whorls  1. sepals- outermost whorls that protect the flower from damage while still a bud  2. petals- 2 nd whorl that attracts pollinators  3. stamens- 3 rd whorl that produces pollen  A. Anther- pollen producing sac  4. pistils- 4 th whorl which produces ovules that develop in the swollen lower part which is called the ovary and has a style, which rises from is A. ANGIOSPERMS, GAMETOPHYTES DEVELOP IN FLOWERS

 C. flowers may or may not have all 4 whorls  1. complete flowers have all four  2. incomplete flowers lack one or more of the whorls  3. perfect flowers contain stamen and pistils  4. imperfect flowers lack a stamen or pistil  D. flowers attract insects that pick up pollen from the stamen and take it to pistils of that flower or other flowers when they pick up the flower’s nectar

 1. the zygote and ovule develop into a seed which grows into a new sporophyte  2. a flower produces male spores inside its anthers and the female spores inside its pistil  3. meiosis occurs  4. spores develop into male and female gametophytes  5. pollination occurs when a pollen grain lands on the stigma of a pistil  6. sperm enters an ovule through a pollen tube and fertilization occurs E. LIFE CYCLE OF AN ANGIOSPERM

V. ASEXUAL REPRODUCTION

 A. Vegetative reproduction is the growth of new plants from non-reproductive plant parts, like stems, roots, and leaves  B. Kalanchoes are succulents that are often grown as potted plants and readily reproduce either vegetatively or by seeds  C. People often grow plants from their vegetative structures which is called vegetative propagation