Chapter 17 Lecture

Chapter 17 Lecture - 1 Chapter 17 The Evolution of Plant...

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1 Chapter 17 Chapter 17 The Evolution of Plant and Fungal Diversity 2 3 PLANT EVOLUTION AND DIVERSITY 4 17.1 Plants have adaptations for life on land ± More than 500 million years ago, the algal ancestors of plants may have carpeted moist fringes of lakes and coastal salt marshes. ± Plants and green algae called charophytes – are thought to have evolved from a common ancestor, – have complex multicellular bodies, and – are photosynthetic eukaryotes. 5 Figure 17.1A 6 Figure 17.1B 7 17.1 Plants have adaptations for life on land ± Life on land offered many opportunities for plant adaptations that took advantage of – unlimited sunlight, – abundant CO 2 , and – initially, few pathogens or herbivores. 8 17.1 Plants have adaptations for life on land ± But life on land had disadvantages too. On land, plants must – maintain moisture inside their cells, to keep from drying out, – support their body in a nonbuoyant medium, – reproduce and disperse offspring without water, and – obtain resources from soil and air. 9 17.1 Plants have adaptations for life on land ± Unlike land plants, algae – generally have no rigid tissues, – are supported by surrounding water, – obtain CO 2 and minerals directly from the water surrounding the entire algal body, – receive light and perform photosynthesis over most of their body, – use flagellated sperm that swim to fertilize an egg, and – disperse offspring by water. 10 Figure 17.1C 11 Figure 17.1C_1 12 Figure 17.1C_2 13 17.1 Plants have adaptations for life on land ± Land plants maintain moisture in their cells using – a waxy cuticle and – cells that regulate the opening and closing of stomata. ± Land plants obtain – water and minerals from roots in the soil and
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–CO 2 from the air and sunlight through leaves. ± Growth-producing regions of cell division, called apical meristems , are found near the tips of stems and roots. 14 Figure 17.1D 15 17.1 Plants have adaptations for life on land ± In many land plants, water and minerals move up from roots to stems and leaves using vascular tissues . Xylem – consists of dead cells and – conveys water and minerals. Phloem – consists of living cells and – conveys sugars. 16 17.1 Plants have adaptations for life on land ± Many land plants support their body against the pull of gravity using lignin . ± The absence of lignified cell walls in mosses and other plants that lack vascular tissue limits their height. 17 Figure 17.UN01 18 17.1 Plants have adaptations for life on land ± In all plants, the – gametes and embryos must be kept moist, – fertilized egg (zygote) develops into an embryo while attached to and nourished by the parent plant, and – life cycle involves an alternation of a – haploid generation, which produces eggs and sperm, and – diploid generation, which produces spores within protective structures called sporangia . ± Pines and flowering plants have
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Chapter 17 Lecture - 1 Chapter 17 The Evolution of Plant...

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