Sexual Reproduction in Seed Plants

1. Sexual Reproduction in Seed Plants

2. I. Reproductive Structures of Seed Plants

3. A. Gymnosperms and Angiosperms • 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

4. B. Reproduce sexually without water • 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

6. I. Seeds

7. A. Review • 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

8. B. Seed Structures • 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

10. II. Cones

11. 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

12. 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

14. D. Life Cycle of a Conifer • 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

16. IV. flowers

17. A. Angiosperms, gametophytes develop in 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- 2nd whorl that attracts pollinators • 3. stamens- 3rd whorl that produces pollen • A. Anther- pollen producing sac • 4. pistils- 4th whorl which produces ovules that develop in the swollen lower part which is called the ovary and has a style, which rises from is

18. 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

20. E. Life Cycle of an Angiosperm • 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

22. V. Asexual Reproduction

23. 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