Transcript Plants have adaptations for life on land

Chapter 17
The Evolution of Plant and Fungal
Diversity
PowerPoint Lectures for
Campbell Biology: Concepts & Connections, Seventh Edition
Reece, Taylor, Simon, and Dickey
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Lecture by Edward J. Zalisko
Introduction
 The Venus flytrap has adaptations to
– capture and
– digest insects.
 More than 600 species of plants
– are carnivores and
– typically live where soil nutrients, including nitrogen
levels, are poor.
 Carnivorous plants absorb and use nutrients,
including nitrogen, from animals.
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Figure 17.0_2
PLANT EVOLUTION
AND DIVERSITY
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Plants have adaptations for life on land
 More than 500 million years ago, plants evolved
from algae.
 Plants and green algae called charophytes
– are thought to have evolved from a common ancestor,
– have complex multicellular bodies, and
– are photosynthetic eukaryotes.
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Figure 17.1A
Plants have adaptations for life on land
 Life on land offered many opportunities for plant
adaptations that took advantage of
– unlimited sunlight,
– abundant CO2, and
– initially, few pathogens or herbivores.
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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.
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Plants have adaptations for life on land
 Unlike land plants, algae
– generally have no rigid tissues,
– are supported by surrounding water,
– obtain CO2 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.
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Figure 17.1C
Key
Vascular
tissue
Pollen
Spores
Leaf
Spores
Flagellated
sperm
Alga
Surrounding
water supports
alga. Whole alga
Leaf
performs photosynthesis; absorbs Stem
water, CO2, and
minerals from
the water.
Roots
Flagellated
sperm
Holdfast
(anchors alga)
Seed
Flagellated
sperm
Stem
Leaf
Roots
Moss
Stomata only on sporophytes;
primitive roots anchor plants;
no lignin; no vascular tissue;
fertilization requires moisture
Fern
Stomata; roots anchor
plants, absorb water;
lignified cell walls;
vascular tissue;
fertilization requires
moisture
Stem
Roots
Pine tree
Stomata;
roots anchor plants, absorb water;
lignified cell walls; vascular tissue;
fertilization does not require moisture
Figure 17.1C_1
Key
Vascular
tissue
Spores
Leaf
Spores
Flagellated
sperm
Alga
Surrounding
water supports
alga. Whole alga
performs photosynthesis; absorbs
water, CO2, and
minerals from
the water.
Flagellated
sperm
Leaf
Stem
Stem
Roots
Roots
Flagellated
sperm
Holdfast
(anchors alga)
Moss
Stomata only on sporophytes;
primitive roots anchor plants;
no lignin; no vascular tissue;
fertilization requires moisture
Fern
Stomata; roots anchor
plants, absorb water;
lignified cell walls;
vascular tissue;
fertilization requires
moisture
Figure 17.1C_2
Key
Vascular
tissue
Pollen
Seed
Leaf
Stem
Roots
Pine tree
Stomata;
roots anchor plants, absorb water;
lignified cell walls; vascular tissue;
fertilization does not require moisture
Plants have adaptations for life on land
HL
 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
– CO2 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.
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Plants have adaptations for life on land
HL
 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.
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Plants have adaptations for life on land
HL
 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.
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Simplest plant
 Early diversification of plants gave rise to seedless,
nonvascular plants called bryophytes, including
– mosses,
– liverworts, and
– hornworts.
 they lack
– true roots,
– leaves, and
– lignified cell walls.
– Reproduce by spores
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Figure 17.2B
Bryophytes
Moss
Liverwort
Hornwort
Seedless vascular plants- Flicinophyta
 About 425 million years ago, vascular plants evolved
with lignin-hardened vascular tissues.
 The seedless vascular plants include
– club mosses
– ferns and their relatives.
– They have hard vascular tissue to transport water to
leaves
– They do not have flower and seed
– They reproduce by spores
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Figure 17.2C
Seedless vascular plants- Flicinophyta
Fern (a pterophyte)
Club moss (a lycophyte).
Spores are produced in the
upright tan-colored structures.
Seed plants
 The first vascular plants with seeds evolved about
360 million years ago.
 A seed consists of an embryo packaged with a food
supply within a protective covering. (they adapted
dry ecosystems)
 Have lignified (woody material) cell wall and strong
supportive tissue.
 These are:
– gymnosperms (including ginkgo, cycad, and conifer
species) and
– angiosperms (such as flowering trees and grasses).
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Gymnosperms -Coniferophyta
– have naked seeds that are not produced in special
chambers and
– Pollination by wind
– include ginkgo, cycad, and conifer species.
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Figure 17.2D
Gymnosperms
Cycad
Ginkgo
Ephedra
(Mormon tea)
A conifer
Figure 17.2D_4
A conifer
Angiosperms- Angiospermophta
– are flowering plants and flowers are the reproductive
organs
– include flowering trees and grasses.
– Seeds are covered by a fruit or a protective layer.
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Figure 17.2E
Angiosperms
A jacaranda tree
Barley, a grass
Comparison of moncotyledon and dicotyledon
plants -HL