Chapter 29: Plant Diversity
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.
How plants colonized land
Chapter 29.1
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 Charophytes
1. Both produce cellulose for cell walls the same way
2. Their peroxisomes have enzymes that reduce effects
of photorespiration (unique to both)
3. Both produce cell plates the same way during cell
division
4. Structure of sperm is closely related
5. Nuclear and chloroplast genetic evidence suggests
close relation
Charophytes
Chara
Spirogyra
2007-2008
Coleochaete
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 Plants
1. Adaptations in growth
–
apical meristem: localized region of cell
division at tips of roots and shoots
2. Adaptations in reproduction
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–
–
–
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 land
Chapter 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 land
Chapter 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