Chapter 18. Land environment: plant and fungi 生醫系劉秉慧老師分機 /03

Transcription

1 Chapter 18 Land environment: plant and fungi 生醫系劉秉慧老師分機 /03

2 Alteration of generation - sporophyte and gametophyte - the dominant generation Diversity of plant - nonvascular plant : moss and its life cycle - vascular plant seedless vascular plants: Ferns - seed plants - gymnosperm - angiosperm Flowering plant life cycle The Fungi - general biology - black bread mold - mushroom - mutualistic relationship - plant and human disease

3 18.1 Onto Land Plants are a diverse group of eukaryotic organisms. Plants, unlike algae, are adapted for living on land. Plants are related, through evolution, to green algae Plants are classified into four groups. Mosses ( 苔蘚, 地衣 ) Ferns ( 蕨類 ) Gymnosperms ( 裸子植物 ) (eg. conifers 針葉松柏科 ) Angiosperms ( 被子植物 ) (eg. flowering plants)

4 conifers

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6 Alternation of Generation The plant life cycle differs from the life cycle of animals. There are two forms of a plant The spore-bearing sporophyte is diploid (2n). The gamete-producing gametophyte is haploid (1n). Sporophyte (2 n) produces haploid spores (n) by meiosis. Spores (n) undergo mitosis to produce the plant gametophyte (n). The gametophyte produces gametes (sperm and egg) through mitosis Fertilization of gametes forms a zygote (2 n) that undergo mitosis and become the sporophyte (2 n)

7 孢子體 孢子囊 減數分裂 配子 細胞分裂 配子體 細胞分裂

8 The Dominant Generation The dominant generation of a plant is the form that we recognize as the plant. For non-vascular plants, the gametophyte (1n) is the dominant generation. For vascular plants, the sporophyte (2n) is the dominant generation. During the evolution of land plants, the sporophyte developed vascular tissue and became the larger, dominant generation of plants. In the life cycle of seed plants, the spores, the gametes, and zygote are protected from drying out in the land environment.

9 This trends occurred as plants became adapted for life on land.

10 18.2 Diversity of Plants Non-vascular plants (those lacking vascular tissue) were the first land plants to evolve. Vascular plants evolved from nonvascular plants.

11 Nonvascular Plants The nonvascular plants include the bryophytes (liverworts and mosses). Bryophytes lack true roots, stems, leaves, and have a dominant gametophyte generation. Gametophyte(1 n) gametes (sperms and egg, 1n) fertilization : flagellated sperm swim in a film of water to reach egg zygotes (2 n) embryo (2n) sporophyte (2n) attached to gmetophyte (1n) produce spores (1n)

12 (1n) Nonvascular Plants (cont.) 2n (1n) Moss (1n)

13 Vascular Plants Vascular plants generally have true roots, stems, leaves. Vascular plants have vascular tissue consisting of the xylem ( 木質部 ) and phloem ( 韌皮部 ).

14 Vascular Plants (cont.) Xylem transports water and minerals up from the roots Phloem transports organic nutrients

15 Seedless Vascular Plants Seedless vascular plants include the club mosses, horsetails, and ferns. Club mosses are found in temperate forests. Horsetails are taller stems with whorls of slender green branches. During the Carboniferous period, these plants dominated the swamp forests and were as tall as trees. The compressed remains of these seedless vascular plants are what formed coal. ( Oil is most likely formed in marine sedimentary rocks and included animal remains)

16 Ferns Ferns are a widespread group of seedless vascular plants. - sporophyte (dominant form) with vascular tissue - gametophyte lacks vascular tissue The fern gametophyte is dependent upon water to achieve fertilization, so ferns are found in moist environments. Some ferns produce rhizomes ( 根莖 ) which allow them to survive in drier areas and grow horizontally in the soil for producing new plants.

17 Maidenhair ferm

18 Fern life cycle 孢子囊 Water is needed

19 Seed Plants Seed plants are the most common plants. Seeds have three major parts. The embryo The stored food supply The seed coat Seed plants have two types of spores and two types of gametophytes. Male Female

20 Seed plants:gymnosperms The ovules ( 胚珠 )and seeds of gymnosperms are exposed on a modified leaf called the scale. Gymnosperm means naked seed. Cycads ( 蘇鐵 ) and conifers are gymnosperms. Conifers are the dominant plants today that produce cones. The needles of conifers have adaptations that resist water loss, allowing these plants to grow in frozen soils where water may be limiting.

21 In seed plants the gametophytes are microscopic in size. Pollen grains are the male, sperm-producing gametophyte. Pollination occurs when the pollen grain fertilizes the female gametophyte. The female gametophyte develops within an ovule ( 胚珠 ), which develops into the seed. In gymnosperms, the ovule is not completely enclosed by sporophyte tissue at pollination. In angiosperms, the ovule is completely enclosed by sporophyte tissue (the ovary 子房 ) at pollination.

22 Seed plant: Angiosperms The angiosperms ( covered seeds ) are the flowering plants. The ovule is completely enclosed by sporophyte tissue (the ovary) at pollination. Angiosperms are also found in nearly all climates and can vary greatly in size from species to species.

23 Flowers have several common structures. The sepals ( 萼片 ), which form the calyx( 花萼 ), protect the flower bud before it opens. The petals( 花瓣 ), which form the corolla ( 花冠 ), help to attract pollinators. The stamen ( 雄蕊 male reproductive structure) consists of the filament and a pollen-producing anther ( 花藥 ). The Flower

24 The Flower (cont.) The carpels ( 心皮 ) have three major regions. The ovary (female reproductive structure) contains the ovules. The style elevates the stigma. The stigma collects pollen. The ovary also produces nectar in some flowers to attract pollinators.

25 Flowering Plant Life Cycle The anther produces male microspores, which undergo mitosis to produce pollens. Within the ovule, female megaspores undergo mitosis to produce the egg. During pollination, a pollen grain is transported to the stigma. The pollen tube germinates and extends a pollen tube to the ovule. The pollen tube delivers two sperm to the egg to carry out double fertilization.

26 Flowering Plant Life Cycle (cont.)

27 Flowering Plant Life Cycle (cont.) The sperms are involved in two fusion events. One sperm fuses with an egg to form a diploid zygote (2 n). One sperm fuses with two other ovule cells to form the triploid endosperm ( 胚乳 3 n). Endosperm ( 胚乳 ) - the embryo uses the seed endosperm as nourishment during germination. - the endosperm is absorbed into the cotyledon ( 子葉 seed leaves).

28 Flowering Plant Life Cycle

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30 18.3 The Fungi ( 真菌 ) Like plants and animals, fungi are generally multicellular eukaryotes. DNA sequence data has indicated that fungi are more closely related to animals than plants.

31 General Biology of a Fungus Fungi produce windblown spores during both an asexual and a sexual life cycle Fungi are composed of thin filaments of cells called hyphae. The hyphae are typically organized into a mass called a mycelium. The mycelium penetrates soil, wood, or other media to acquire nutrients. mycelium hyphae

32 The fungi: Black Bread Mold The hyphae ( 菌絲 ) of some fungi - grow horizontally and vertically to anchor the fungi and acquire nutrients. - involved in fungal reproduction. A sporangium - is a structure that produces spores. asexual reproduction - the fungal spores (1 n) divide mitotically to produce new hyphae (1 n). sexual reproduction - the conjugation of mycelia to form zygospore - One is the positive (+) mycelium. - The other is the negative (-) mycelium

33 2 n 1 n 1 n Hyphae 1 n 減數分裂 Spore 1 n

34 The fungi: Mushroom Mushroom forms through sexual production - a positive and negative hyphae fuse (the nuclei do not fuse) together - The dinucleic cells form a stalk and a cap - A mushroom is the fruiting body of a fungi. - basidium( 孢子臺 ), within the gills of the cap, are spore-producing structures

35 1 n 孢子臺 減數分裂 子實體 Hyphae 1n

36 Mutualistic Relationships Two different species contribute positively to each other s growth. Lichens produce organic matter and create new soil, allowing plants to invade the area Lichens ( 地衣 ) are a mutualistic relationship - fungi and cyanobacteria - fungi and algae. Lichens have three cell layers. An upper and lower fungal cell layer A middle algal or cyanobacteria layer ( photosynthetic cells) The fungus provide mineral and water to the photosynthetic cells

37 Mutualistic Relationships (cont.)

38 Fungi and Plant Diseases Certain fungi can cause disease in plants and animals, acting as pathogens. Fungal pathogens of plants usually enter through wounds or the stomata. Some fungal diseases impact agricultural production. Rice blast disease Corn smut ( 黑穗病 ) Rusts Leaf curl

39 Fungi and Human Diseases Mycoses are diseases caused by fungi. Mycoses have three levels of infection. Cutaneous mycoses only affect the epidermal layers. Subcutaneous mycoses affect deeper skin layers. Systemic mycoses spread throughout the body.

40 Fungi and Human Diseases The widest array of fungal diseases are caused by Candida albicans. Yeast infections in women Oral thrush in new born and AIDS patient can cause a systemic infection that can damage the heart, brain, and other organ Fungi from the genus Tinea contribute to the ringworm and athlete s foot. - cutaneous infection only