Lecture Notes on Characteristics of Nonvascular Plants | BIO 406D, Study notes of Biology

Download Lecture Notes on Characteristics of Nonvascular Plants | BIO 406D and more Study notes Biology in PDF only on Docsity! Nonvascular Plants Characteristics of Nonvascular Plants Eukaryotic Multi-celled (with cell walls composed of cellulose) Autotrophic Do not have xylem and phloem Do not produce seeds Do not produce flowers or fruits The Groups of Nonvascular Plants Liverworts Hornworts Mosses Meiosis and Fertilization Diploid (2n) organisms have pairs of chromosomes (e.g., humans have 23 pairs of chromosomes for a total of 46; there are two number one chromosomes, two number two chromosomes, etc.) Meiosis is the process by which the chromosomes of pairs in diploid (2n) cells are separated from one another and haploid (n) cells are produced (e.g., in humans, meiosis will give rise to cells with 23 chromosomes, one from each pair) Fertilization is the process by which two haploid (n) gametes (sex cells) fuse to produce a diploid (2n) zygote By definition, gametes are haploid (n) and zygotes are diploid (2n) Mitosis Mitosis is the process by which cells divide to produce genetically identical daughter cells A diploid (2n) cell can divide by mitosis to give rise to a population of genetically identical diploid (2n) cells A haploid (n) cell can divide by mitosis to give rise to a population of genetically identical haploid (n) cells Typical Plant Life Cycle A haploid (n) spore divide by mitosis to produce a haploid (n) multicellular gametophyte Haploid (n) cells of a mature gametophyte divide by mitosis to produce haploid (n) gametes Gametes (n) fuse in fertilization to form a diploid (2n) zygote The zygote (2n) divides by mitosis to produce a diploid (2n) multicellular sporophyte Diploid (2n) cells of the mature sporophyte divide by meiosis to produce haploid (n) spores By definition, gametophytes produce gametes and sporophytes produce spores Typical Moss Life Cycle Haploid (n) spores germinate and divide by mitosis to produce haploid (n) multicellular gametophytes, some of which are male gametophytes and some of which are female gametophytes Haploid (n) cells of mature male gametophytes in structures called antheridia (singular – antheridium) divide by mitosis to produce haploid (n) male gametes (sperm), and haploid (n) cells of mature female gametophytes in structures called archegonia (singular – archegonium) divide by mitosis to produce haploid (n) female gametes (eggs) Haploid (n) male gametes are transferred via rainwater or dew from antheridia of male gametophytes to archegonia of female gametophytes where a haploid (n) sperm cell fuses with a haploid (n) egg cell (fertilization) within an archegonium to form a diploid (2n) zygote The zygote (2n) divides by mitosis within the archegonium to produce a diploid (2n) multicellular sporophyte that remains attached to the female gametophyte Diploid (2n) cells of the mature sporophyte in a structure called a capsule (which is a sporangium) divide by meiosis to produce haploid (n) spores Haploid (n) spores are released from the sporangium and fall to the ground where they germinate and divide by mitosis ……