Tobin and Dusheck: Asking About Life, 3E__________ Chapter 22 Copyright 2005 Brooks/Cole Thomson...
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Transcript of Tobin and Dusheck: Asking About Life, 3E__________ Chapter 22 Copyright 2005 Brooks/Cole Thomson...
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Chapter 22
How Did Plants Adapt to Dry
Land?
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Key Questions• How did plants adapt to life on land?• How do bryophytes survive on land
without vascular tissues?• What are the advantages of a
vascular system?• How are seeds an adaptation to a
dry, terrestrial environment?• What roles do flowers and fruits play
in angiosperm reproduction?
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
What Is a Plant?
• Multicellular organism that performs photosynthesis and develops from an embryo
• Almost all live on land• Descendants of protists• Land invasion depended on
evolution of different structures
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Land Adaptations• Waxy cuticle — reduces water
loss• Ability to absorb water from a
variety of sources• Enclosed reproductive organs,
called gametangia, in which gametes form
• Enclosed sporangia in which spores form
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Identify Different Plant Types
• Identify as many different plants as you can. How are they different from one another?
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Vascular vs. Nonvascular• Vascular or
tracheophytes• Have pipelike
tissues that conduct water
• Grow large• Examples: fir
trees, ferns
• Nonvascular or bryophytes
• Lack a vascular system
• Much smaller• Less diverse
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
The Divisions of Plants
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Evolution of Plants
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Plant Evolution• Evidence comes from fossils and
comparisons with living species• First plants evolved from a
common ancestor that resembled a green alga
• Vascular plants predate nonvascular plants
• First seedless plants — Carboniferous Period
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Kingdom Plantae
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Angiosperm Evolution
• Angiosperms — flowering plants• First fossils — about 125 million
years ago• Evolved from gymnosperms —
plants that have no fruits or flowers
• Many adaptations
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Mosses, Liverworts and Hornworts
• Nonvascular Plants or bryophytes
• Depend on free standing water for photosynthesis and fertilization
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Bryophyte Characteristics
• All parts of their bodies are adapted to absorb water
• This gives them a spongy feel• Exhibit alternation of generations
— a sexual life cycle in which haploid and diploid phases are both multicellular
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Life Cycle of a Moss
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Vascular Plants
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Vascular Plants• Called tracheophytes• Have division of labor with separate
transport systems for water (xylem) and sugars (phloem)
• Diploid Phase dominates the life of the plant
• Seeds are protected by coat, and food is stored inside for germination
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Seed-Lacking Tracheophytes
• 4 divisions that lack seeds:– Pterophytes (ferns)– Psilotophytes– Lycophytes– Equisetophytes
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Life Cycle of a Fern
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Life Cycle of a Fern
• A fern releases haploid spores• Spores mature into haploid
gametophytes• Gametophytes make sperm and
egg• Fusion of sperm and egg• Zygotes grow right out of the
gametophyte for a new fern
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Lycophytes
• Have true roots, stems and simple leaves
• Also called lycopods
• Example: club mosses
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Equisetophytes• Referred to as
horsetails• Have true roots,
stems and complex leaves
• Stems are jointed
• Outer cell walls are reinforced with silica
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Reproduction in Seed Plants• Manage fertilization without water• Use a form of internal fertilization• Sperm and ovum fused, and
develop within the female gametophyte
• Seeds consist of a diploid zygote and a source of food encased in a seed coat
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Gymnosperms
• Seed plants without flowers• Evergreen• Conifers produce male and
female gametophytes in cone-shaped strobili (the cones)
• Male and female cones on same tree
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Life Cycle of a Pine
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Cycads• Large-leafed
plants that look like palms
• No flowers or fruits
• Bear naked seeds
• Produce male and female strobili
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Ginkgos• Either male or
female• Resemble
cycads in their life cycle
• Resemble conifers in their growth patterns
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Uses of Flowers and Fruits
• Flowers ensure distribution of pollen through a variety of methods
• Fruits are mature ovaries that enclose and protect seeds
• Fruits usually enhance dispersal of seeds
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Life Cycle of a Flowering Plant
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Angiosperm Reproduction
• Flowers reproduce by means of double fertilization
• 2 sperm nuclei from the pollen grain fertilize 2 ova from the ovary
• A diploid zygote is formed and a triploid cell forms the endosperm
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Flower Parts
• Stamen — anther and filament (male)
• Carpel — style and ovary (female)
• A corolla or petals and a calyx of sepals surround stamens and carpels
• Not all flowers have all parts
Copyright 2005—Brooks/Cole—Thomson Learning
Tobin and Dusheck: Asking About Life, 3E __________ Chapter 22
Key Concepts• A plant is a multicellular organism
that photosynthesizes and develops an embryo
• Nonvascular plants lack vascular tissues
• The vascular system enables plants to transport water and nutrients, to grow large, and to diversify
• Seeds allow plant to withstand dry environments