1. ALTERNATION OF GENERATIONS AND PLANT LIFE CYCLES Copyright © 2009 Pearson Education, Inc.

2. Haploid (n) Diploid (2n) Key Gametophyte plant (n) Gametes (n) Sperm Egg Fertilization Zygote (2n) Sporophyte plant (2n) Meiosis Spores (n) Mitosis

3. Male Haploid (n) Diploid (2n) Key Gametophytes (n) Female Sperm (n) Egg (n) Fertilization Female gametangium 1 1 2 Zygote (2n) Sporophyte (2n) 3 Mitosis and development Sporangium Stalk 4 Meiosis Spores (n) 5 Mitosis and development

4. Haploid (n) Diploid (2n) Key Gametophyte (n) Sperm (n) Egg (n) Fertilization Female gametangium (n) 1 2 Zygote (2n) New sporophyte (2n) Mitosis and development Meiosis 3 4 Mature sporophyte Clusters of sporangia Mitosis and development 5 Spores (n)

5. Sporangia produce spores; spores develop into pollen grains. Spore mother cell (2n) Meiosis 1 Sporangium (2n) Scale Integument Pollination Ovule Meiosis 2 3 Pollen grains (male gameto- phytes) (n) Ovulate cone bears ovules. Haploid (n) Diploid (2n) Key Mature sporophyte Egg (n) Fertilization Female gametophyte (n) Male gametophyte (pollen grain) Sperm (n) A haploid spore cell develops into female gametophyte, which makes eggs. 4 Pollen grows tube to egg and makes and releases sperm. 5 Seed coat Zygote (2n) Zygote develops into embryo, and ovule becomes seed. 6 Food supply Embryo (2n) Seed 7 Seed germinates, and embryo grows into seedling.

6. Meiosis 1 Haploid (n) Diploid (2n) Key Egg (n) Fertilization Sperm Seed coat Zygote (2n) Food supply Embryo (2n) Seeds Haploid spores in anthers develop into pollen grains: male gametophytes. 2 Meiosis Pollen grains (n) Ovule Haploid spore in each ovule develops into female gameto- phyte, which produces an egg. 3 Pollination and growth of pollen tube Stigma Pollen grain Pollen tube 4 Fruit (mature ovary) 6 Seed 5 Ovary Ovule Stigma Anther Sporophyte (2n) Seed germinates, and embryo grows into plant. 7