BIOL101 Study Guide - Midterm Guide: Gametangium, Sporopollenin, Antheridium
Document Summary
Land plants evolved from green algae and share several characteristics, such as their absorption spectrum and their cellular make up. Four key traits appear in nearly all land plants but are absent in charophytes: alternation of generations (with multicellular dependent embryos) Alternation between two multicellular stages: walled spores produced in sporangia. Spore walls contain sporopollenin, which makes spores resistant to harsh environments: multicellular gametangia. Gametes produced within organs called gametangia: apical meristems. Land plants only share four key traits with charophytes: rings of cellulose synthesizing complexes, peroxisome enzymes, structure of flagellated sperm, formation of a phragmoplast. The gameophyte is haploid and produces haploid gametes by mitosis. Fusion of the gametes gives rise to the diploid sporophyte, which produces haploid spores by meiosis. The diploid embryo is retained within the tissue of the female gametophyte. Nutrients are transferred from parent to embryo through placental transfer cells.
