During her research, Colleen learned that spermatophytes are a very diverse group of plants that can be divided into two main categories: gymnosperms and angiosperms. Gymnosperms, or "naked seeds," are cone-bearing seed plants while angiosperms, or "closed seeds," are flower-bearing seed plants.

View the slideshow below to learn about the general life cycle of gymnosperms. While viewing, pay special attention to all the processes (pollination, fertilization, germination) and the cellular divisions (meiosis and mitosis).

Adult Sporophyte An adult sporophyte is able to reproduce. Since the sporophyte is diploid, it has the complete set of DNA. Through meiosis, haploid cells known as gametes are produced. Male gametes are found on male cones and female gametes are found on female cones. How much DNA do haploid cells have? Haploid cells have a half set of DNA. Male Gametes Male gametes, also known as pollen grains, are light weight and numerous. They can travel long distances with the wind to deliver their DNA to female cones. This process is called pollination. Why are so many pollen grains produced? To increase the chance of pollination taking place. Female Gametes Female gametes, also known as eggs, are stored in protective ovaries. If pollination occurs, then the DNA contained in the pollen may fuse with the DNA contained in the egg. This process is known as fertilization. What's the difference between pollination and fertilization? Pollination is the delivery of pollen grains to a female cone. Fertilization is when male and female gametes fuse. Embryo Seeds Embryo seeds are the result of fertilization and mitotic division. Fertilization joins two haploid gametes, the egg and pollen, and creates a diploid zygote. The zygote undergoes mitosis to become a multicellular embryo. Since the embryo is within a protective seed, it can stay alive for a long period of time until conditions are favorable for it to grow into a tree, which is known as germination. What's the difference between mitosis and meiosis? Mitosis is a cellular division that creates a population of same type of cells. Meiosis is a cellular division that creates different haploid cells. Life Cycle The dominant part of the gymnosperm life cycle is the sporophyte, which produces gametes. The gametophyte part of the life cycle is responsible for producing seeds. Which part of the gymnosperm life cycle is sexual? The gametophyte part of the life cycle is sexual.