Chapter 16 - Plants, Fungi, and the Move onto Land Terrestrial Adaptations - living on land poses different problems from living in water Plants require structural specializations Roots and shoots Shoots Leaves – photosynthesis and gas exchange Stems – transport water up and sap down Roots – absorb water and dissolved minerals..

Leaves are main photosynthetic organs Gametangia protect gametes from dehydration; female gametangia protect developing embryos Cuticle reduces water loss Stomata allow gas exchange between plant and atmosphere Lignin hardens cell walls Shoot supports plant; may perform photosynthesis Vascular tissues transport water, minerals, and sugars; provide support Roots anchor plant; mycorrhizae (root/fungus associations) help absorb water and minerals from the soil) Whole alga performs Photosynthesis; absorbs water, CO2, and minerals from the water Alga Surrounding water supports the alga

True root, stems, and leaves have vascular tissue that form “veins” in the tissues. Xylem – transports water and minerals through dead cells that form “straws” in the tissue Phloem – living cells that transport sap (sugars in water) throughout the plant..

Plant Diversity Angio-sperms Gymnosperms (e.g., conifers) Cenozoic Mesozoic Paleozoic Charophyceans (a group of green algae) Bryophytes (e.g., mosses) Seedless vascular plants (e.g., ferns) Gymnosperms (e.g., conifers) Angio-sperms Origin of plants Early vascular plants First seed plants Diversification of flowering plants

Nonvascular Plants – Bryophytes No vascular tissue, must be low to ground, live in moist areas, no true roots, stems, or leaves Mosses – the most familiar..

Plants, including mosses, have two distinct versions of the plant The gametophyte, which produces gametes The sporophyte, which produces spores (phyte = plant)..

Gametes (sperm and eggs) The life cycle of a moss exhibits an alternation of generations Spores n Mitosis Sporophyte 2n Gametes (sperm and eggs) Fertilization Zygote Spore capsule Meiosis Gametophyte Haploid Diploid

Seedless Vascular Plants - Ferns Have vascular tissue; true roots, stems, and leaves; do not produce seeds; have flagellated sperm that swim to ovule

Seed Plants – Gymnosperms & Angiosperms Seed – embryonic plant with food supply packaged in a protective coat..

Gymnosperms - Conifers Most all are evergreens; produce seed cones and pollen cones; sporophyte generation is more prominent than the gametophyte generation..

Pollen grain Ovule Is actually the much-reduced male gametophyte Fertilizes the female gametophyte Ovule Contain the female gametophyte Will develop into the seed..

Angiosperms Supply nearly all our food and much of our fiber for textiles More efficient water transport and the evolution of the flower help account for the success of the angiosperms

A characteristic of angiosperms is double fertilization One sperm nucleus fertilizes and egg in the female gametophyte = zygote One sperm nucleus fertilizes another cell in the female gametophyte (not the egg) = endosperm This synchronizes the development of the embryo and the food reserves. The entire ovule develops in to a seed. Integuments Spore (a) Ovule Haploid (n) Diploid (2n) Pollen tube Pollen grain (male gametophyte) Female gametophyte Egg nucleus Discharged sperm nucleus (b) Fertilized ovule Seed coat (derived from integuments) Food supply (derived from female gametophyte tissue) Spore case Embryo (new sporophyte) (c) Seed..

Life cycle of Angiosperms Mature sporophyte plant with flowers Germinated pollen grain (male gametophyte) on stigma of carpel Anther at tip of stamen Pollen tube growing down style of carpel Ovary (base of carpel) Embryo sac (female gametophyte) Egg Sperm nuclei Fertilization Endosperm Zygote Embryo (sporophyte) Fruit (develops from ovary) Seed (develops from ovule) Seed Germinating seed Sporophyte seedling Haploid (n) Diploid (2n).. Ovule Life cycle of Angiosperms

The dominant stage of the angiosperms is a sporophyte with gametophytes in its flowers Stamen Anther Filament Ovule Petal Pistil Stigma Style Ovary Sepal Contains female gametophyte.. Contains male gametophyte = pollen

Fruit = ripened ovary usually containing seeds.. Flower Sepals = outer whorl of modified leaves; protection Petals = second whorl of modified leaves; bright, showy; attract pollinators Stamen = anther & filament; produces pollen – the male gametophyte Pistil = stigma, style, & ovary with ovules; ovules contain the female gametophyte Fruit = ripened ovary usually containing seeds..