Transcript BIO120 LAB--PLANT DIVERSITY 1-

PLANT DIVERSITY 1
BE SURE TO READ THE
DESCRIPTIONS OF
ALTERNATION OF
GENERATIONS AND THE
CHARACTERISTICS OF
THE PLANT GROUPS IN
THE LAB MANUAL
The Next Two Weeks:
overview of plant groups
• PLANT KINGDOM (major groups)
Vascular
– MOSSES (“non-vascular”)
seedless
– FERNS
– GYMNOSPERMS (conifers)
– ANGIOSPERMS (flowering plants)
WHY PLANTS MATTER
• Base of food chain
– They are the ultimate/fundamental source of nutrients
– Make organic molecules available to other organisms (they fix carbon,
make N-available)
• Make O2 available & remove CO2 from atmosphere
• Source of raw materials/resources
– Wood (building materials)
– Paper
– Cloth/fabric
• Stabilize soil
• Cool and humidify environment
• Source of medicine, chemicals, etc…
• Aesthetics
Defining Characteristics of the Plant Kingdom:
You know it’s a plant when…
• Multicellular
• Eukaryotic
• Photosynthetic Autotrophs
– Chlorophyll
• Cell Walls of Cellulose
• Non-motile/mobile
• Alternation of Generations
ALTERNATION OF
GENERATIONS:
see also diagram in lab manual
• Gametophyte: muticellular haploid—
– HAPLOID = 1 COPY OF EACH CHROMOSOME
– Produces unicellular haploid GAMETES (by mitosis)
that fertilize one another to make:
• Sporophyte: multicellular diploid—
– DIPLOID = 2 COPIES OF EACH CHROMOSOME
– Produces unicellular haploid SPORES (by meiosis)
that divide by mitosis to make the GAMETOPHYTES
DIPLOID: 2 copy of
each chromosome
HAPLOID: 1 copy of
each chromosome
If humans had alternation of generations
Background Concepts
Reproduction:
• ASEXUAL REPRODUCTION:
– Clones: offspring are genetically identical to one another and
parent
– Fast, cheap, easy
– Low risk to parent, and if environment is stable produces lots of
successful offspring quickly
• SEXUAL REPRODUCTION:
– Genetically different/variable: offspring are different from
parent and one another
– Slower, riskier, more expensive, for parent
– but creates potential for offspring to have new and different
capabilities that could make them more successful or capable of
dealing with a changing environment.
Background Concepts Cont.
Vascular Tissue:
Specializes cells that transport materials around the plant
Can transport “long distance”
– XYLEM:
• transports materials absorbed from soil: water and minerals.
• creates rigid support (so plant can grow big)
– PHLOEM:
• transports sugars made by photosynthesis
Plants
Algae
Aquatic common
ancestor of both
plants and algae
Aquatic photosynthetic organism, that
existed at some point in history, common
ancestor to both algae and plants
Various levels of
adaptation to dry
land
In the aquatic env:
• Obtaining water
• Drying out
• support
• Sperm swimming to egg
PLANTS ARE TERRESTRIAL:
Challenges of life on land…..
• Obtaining water
– how do they get water to cells that need it?
• Drying out
– how to prevent loss of water they have?
– both the adult and juvanile plant
• Support (against gravity)
– how do the plants support themselves as they grow upright (if
they do)
• Reproduction with swimming sperm in a terrestrial
environment
– How does the sperm get to the egg when it needs to swim
– Also, sperm must not dry out as well
Adaptation
• Any characteristics that allows an
organism to better survive and reproduce
in its environment
– Physical (morphological)
– Physiological
– Behavioral
HOW PLANTS WORK
• Use Water (from ground), CO2, and sunlight energy to make food
•
WATER + CO2  SUGARS
–
–
this is photosynthesis
This happens mostly in leaves (which also lose water)
MOSSES AND LIVERWORTS:
• No vascular tissue
• swimming sperm
• no true roots or leaves
MOSSES AND LIVERWORTS:
• What environment do they require?
• Why are they limited to this environment?
• How does sperm get to egg? Under what
conditions?
• How do they obtain water?
• Do they have vascular tissue? true roots?
• Dominant Generation?
• Why do they have to be smal
MOSSESL AND LIVERWORTS:
• WHY ARE THEY SMALL?
– give two reasons
• WHY MUST THEY LIVE IN WET
ENVIRONMENTS?
– give two reasons
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FERNS:
Have vascular tissue
Have roots and true leaves
have swimming sperm
have spores
FERNS:
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Do they have vascular tissue?
What are the leaves called?
What are their reproductive structures?
What are in sori
Roots?
Dominant Generation?
Do they grow tall?
Why can they grow this tall
How are they better adapted to dry land
than mosses/liverworts
FERNS:
• Why can they grow bigger then mosses?
– give two reasons
• Why might you find ferns growing in
places that are too dry for mosses?
• What kind of environments are they
restricted to by reproduction?
– what do they need for reproduction
Stomata
• Openings in leaves that allow:
– gas exchange (primarily allows CO2 into plant)
– water to exit plant
– some water loss is necessary/needed, but too much is bad.
• The opening (stomata) are borded by two cells called
guard cells.
– Guard cells can open and close the stomata
– If the stomata are closed what does that do to gas exchange?
Water loss?
• What surface of the leaf has most of the stomata?
• Why does that make sense given that water is lost
through the stomata?
many stomata
Stomata w/ guard cells