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Characteristics of plants Ch 16 Evolution of Plants Eukaryotes (nucleus, internal organelles) Multicellular Photosynthetic Make organic molecules by photosynthesis Autotrophs: feed themselves (and animals) The dominant organisms on land Plant evolution: Adapting to Living on Land Plants evolved from green algae Both Perform photosynthesis Store excess carbohydrates as starch Plant evolution: Adapting to Living on Land To live on land, plants evolved specialized structures Highlights of Plant Evolution 1. 3. 4. Roots Support Cuticle (waxy covering) Leaves Methods of reproducing on land Terrestrial adaptations: Conserving water Adaptations to living on land 2. Over 263,000 species of plants Water conservation Support Specialized structures to protect gametes and embryos Vascular tissue Seeds Flowers The waxy cuticle helps the plant retain water Specialized pores called stomata (singular, stoma) allow gas exchange through the cuticle Green algae A stoma the cuticle prevents water loss to the air They open and close Terrestrial adaptations: Vascular tissue How do plants transport water and food between the roots and leaves? A system of tubes (veins) conducts water and food throughout the plant Terrestrial adaptations: Reproduction How do plants protect their gametes and embryos from drying out? Developed protective structures called gametangia. Sexual reproduction on land – a special challenge Evolution of plants Plants can’t move – how do they pass gametes from one plant to another? The embryo develops in a moist chamber which keeps it from dehydrating. Key innovations early plants used spores for reproduction later pollen evolved transferred by wind or insects Bryophytes: simple, nonvascular plants Mosses Evolved first No vascular system Lack true roots and leaves Bryophytes Ferns Gymnosperms Angiosperms The most familiar bryophytes Terrestrial adaptations Vascular tissue Seeds Flowers and fruits The many plants in a mat of moss hold each other up Need water to reproduce Key terrestrial adaptations: A waxy cuticle helps prevent dehydration Embryos develop within the gametangia The evolution of vascular tissue Vascular tissue – specialized cells that form a network throughout a plant Xylem–conducts water Evolution of Vascular Tissue Phloem–conducts sugars made in the leaves throughout the plant Can grow tall due to vascular tissue Reproduce with spores from the roots to the leaves Ferns Can develop into new organism without fusing with another cell Seedless vascular plants “Fiddlehead” (young leaves ready to unfurl) Seeds – Basic structure of seeds a key adaptation to living on land A drought-resistant protective cover Embryo Food for the developing embryo, endosperm Improve the dispersal of plants into new habitats Permit plants to postpone development until conditions are favorable Improve germination In some seeds, food is stored in leaf-like structures called cotyledons Evolution of Seed Plants Plant develops with warm temperature, rainfall Provide food for the young plant Seed plants are divided into two groups Seed plants produce two kinds of gametophytes Provide dormancy pollen grains = male eggs within ovules = female There is no need for water in the fertilization process The plant is pollinated by the wind, insects, birds, or other agents The pollen grain cracks open and sprouts a pollen tube, which transfers the male gametophyte directly to the egg Bryophytes Ferns Seeds Gymnosperms Seeds produced in cones Angiosperms Flowers bear seeds within the ovary Gymnosperms The life cycle of conifers Female cones Male cones Have a vascular system and “naked” seeds but no flowers Conifers form two types of cones Seed-bearing cones contain the female gametophytes Conifers are an example of gymnosperms Seeds are produced in cones where pollination occurs Smaller male cones produce pollen (male gametophytes) Pollen grains travel by wind to the seed-bearing cones Plant reproduction: pine tree 2:42 http://www.youtube.com/watch?v=DzP7xEDH ZKc&feature=channel Angiosperms: Angiosperms or Flowering plants Bryophytes Flowers are reproductive structures Ferns Gymnosperms Angiosperms 90% of all living plant species are angiosperms Why so successful? contain pollen (“male”) and eggs (“female”) Ovule is completely enclosed by the ovary Flowers improve the efficiency of mating attract pollinators – insects, butterflies, birds, etc Evolution of the flower What do flowers have in common? Why are there different kinds of flowers? Sepals – enclose the flower Petals – attract pollinators Stamens – “male” parts that before it opens produce pollen the anther at the tip of the stamen contains pollen Carpel – the “female” part of the flower that produces the egg the ovules are enclosed in the ovary the stigma receives pollen Pollination, pollination, pollination Flowers vary in size, shape and color so that they can be identified by a particular pollinator Insects specialize in pollinating particular kinds of flowers This improves the likelihood that the pollen will be carried to a flower of the same species Wind pollination Insect pollination Many plants, such as grass, weeds and even large pine trees, rely on the wind for pollination. The pollen is small and light, allowing it to be blown by the wind. The pollen lands on other plants a fertilizes them. The pollen grain produces 2 sperm cells one fertilizes the egg, develops into the embryo the other fuses with the central cell, producing endosperm Evolution of Fruit Another key advance in angiosperms Fruit Forms from the ovary, contains seeds Helps protect the seed and improves seed dispersal Is a major food source for animals common insect pollinator As a bee gathers nectar from a flower, tiny grains of pollen stick to its hairy legs and body. When the bee flies to another flower, the pollen on its legs and body brushes off to help fertilize the flower. Double fertilization – only in angiosperms The life cycle of an angiosperm Bees are the most a highly nutritious tissue that is food for the embryo Seed dispersal Fruits are specialized for dispersing seeds Common methods of dispersal Wind Water Attaching to animals Fleshy fruits are eaten The seed germinates Plants and Agriculture Germination – resumption of the seed’s growth and development Triggered by water and temperature Gymnosperms Angiosperms wheat supply most of our lumber and paper Provide nearly all our food Supply fiber, medications, perfumes, and decoration cotton Kingdom Fungi FUNGI Eukaryotes Most are multicellular Heterotrophs They digest their food externally and absorb the nutrients from the environment Fungi are extremely important to ecosystems because they decompose and recycle organic materials Discovery Channel 16-22 Fungi Structure of fungi Reproductive structure Hyphae Sporeproducing structures Bodies are constructed of hyphae Mushrooms are reproductive structures that extend from the underground mycelium Lichens: another symbiotic relationship Mycelium Symbiotic associations of fungi and algae The photosynthetic algae feed the fungi The fungal mycelium provides a habitat for the algae, helps them absorb water and minerals The merger is so complete that lichens are named as species