chapter 29: plant diversity
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Admit Slip 3. List 3 words you think of when you look at the picture/diagram 2. Write 2 ideas you have based on the picture and your words. If possible, use your words as you write your ideas. 1. Write 1 question you have. Chapter 29: Plant Diversity. How plants colonized land Chapter 29.1. - PowerPoint PPT PresentationTRANSCRIPT
Chapter 29: Plant Diversity
How plants colonized landChapter 29.1
Admit Slip3. List 3 words you think of when you look at the picture/diagram
2. Write 2 ideas you have based on the picture and your words. If possible, use your words as you write your ideas.
1. Write 1 question you have.
Plants supply oxygen and are the ultimate provider of most of the food eaten or absorbed
by other organisms.
Terminology
• -phyte=Plant• Bryo=moss• Ptero=fern• Gymno=naked• Mitosis: division of cells-forms identical copy with full set of
chromosomes (2n), body cells• Meiosis: division of cells-forms a cell with a half set of
chromosomes (n), sex cells• Haploid: half the total chromosomes for an organism
(egg/sperm)• Diploid: full number of chromosomes for an organims (somatic)
What problems do terrestrial habitats offer for plants????
Land plants evolved from green algae
• Evolved from Charophytes (green algae) more than 500 million years ago.
• Evidence for evolution from Charophytes1. Both produce cellulose for cell walls the same way2. Their peroxisomes have enzymes that reduce effects of
photorespiration (unique to both)3. Both produce cell plates the same way during cell division4. Structure of sperm is closely related5. Nuclear and chloroplast genetic evidence suggests close
relation
2007-2008
Charophytes
Spirogyra
Coleochaete
Chara
Problems of life on land
Problems of life on land
Movement of plants from sea to land
• Advantages:– Increased sunlight (unfiltered by water)– More carbon dioxide in atmosphere than
water– Soils rich in nutrients– Fewer predators
• Challenges– Lack of water– Desiccation– Lack of structural support against gravity
Adaptations of Land Plants1. Adaptations in growth– apical meristem: localized region of cell
division at tips of roots and shoots2. Adaptations in reproduction– alternation of generations– walled spores: protect spores in harsh
environments– multicellular gametangia: structures for
gamete production– multicellular dependent embryos:
transfer of nutrients from tissue to embryo
3. Adaptations against water loss– Cuticle
Alteration of Generations
• All land plants have two multicellular stages– Gametophyte• plant cells are haploid• Gametes are produced
– Sporophyte• plant cells are diploid• Divides mitotically• Sporophyte produces spores through meiosis
Alteration of Generations
• During fertilization: gametes (egg and sperm-both haploid) fuse to form a diploid zygote (sporophyte)
• Zygote develops in tissues of female parent getting nutrients from it, sometimes called an embryophyte
Gametangia
• Plants produce gametes in multicellular structures called gametangia– Female: archegonia-produces a single egg– Male: antheridia-produces many sperm
Chapter 29: Plant Diversity
How plants colonized landChapter 29.2
Bryophytes
• Moss• Nonvasular (small size)• Seedless• Life cycle dominated
by gametophyte stage• Water required for
sperm to swim to the egg during fertilization
Bryophyte life cycle
Chapter 29: Plant Diversity
How plants colonized landChapter 29.3
Pteridophytes/Ferns
• First plants with vascular tissue– Allowed plants to grow tall and gain access to
sunlight• Seedless• Require film of water for sperm to reach egg
• Life cycle dominated by the sporophyte stage– Meiosis occurs in sporangia producing haploid
spores which may grow into gametophytes with anteridia (release sperm) and achegonium (produce egg, house zygote after fertilization)
Pteridophytes/Ferns life cycle
Evolution of land plants