plant diversity ii: seed plants - linn–benton community...
TRANSCRIPT
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Plant Diversity II: Seed Plants
Angiosperms and Gymnosperms
Pesticides!
Include:
Herbicides
Insecticides
Fungicides
Rodenticides
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Pesticides are pervasive Studies of major rivers and streams document
that 96% of all fish,
100% of all surface water samples
33% of major aquifers contain one or more pesticides at detectable levels
Surface water= In a large sampling of streams throughout the country, USGS found 46 pesticides and pesticide degradation products in one or more samples
Groundwater= A 1989 study found residues of 39 pesticides and their degradation products in the groundwater of 34 states and Canadian provinces
Dozens of pesticides and their degradation products contaminate waterways and escape regulatory oversight
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Runoff from urban lawn pesticides contaminates local watersheds and stresses municipal water treatment.
Pesticides harm humans Human health effects,
including low birth weights,
breast cancer, and
low sperm counts are linked to herbicide-contaminated water
Children are not adequately protected by federal limits of pesticides in water.
USGS found that more that 90% of water and fish samples from all streams sampled in the U.S. contain at least one pesticide
USGS. 1999. The Quality of Our Nations Water: Nutrients and Pesticides. USGS Circular
1225. [http://permanent.access.gpo.gov/waterusgsgov/water.usgs.gov/pubs/circ/circ1225/]
Kettles, MA, SR, Browning, TS Prince, and SW Horstman.
1997. Triazine herbicide exposure and breast cancer
incidence: An ecologic study of Kentucky counties.
Environmental Health Perspectives 105(11):1222-1227.
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Pesticides harm wildlife
Frogs exhibit hermaphrodism when exposed to legally allowable levels of the herbicide atrazine in waterways
A study of sex hormones in carp indicates that pesticides may be affecting the ratio of estrogen to testosterone in both male and female fish.
They have also caused fish kills.
Goodbred, S.L., Gilliom, R.J., Gross, T.S., Denslow, N.P., Bryant, W.L., and Schoeb, T.R., 1997, Reconnaissance of 17b-estradiol, 11-
ketotestosterone, vitellogenin, and gonad histopathology in common carp of United States streams—potential for contaminant-induced
endocrine disruption. U.S. Geological Survey Open-File Report 96-627.
1. Which of the following is NOT a plant adaptation for life on land?
a) Roots, which stabilize and absorb water and nutrients from soil
b) A waxy cuticle, which prevents water loss
c) Colonial living, which maximizes use of resources while expending less energy
d) Stomata, which allow for gas exchange
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1. Which of the following is NOT a plant adaptation for life on land?
A. Roots, which stabilize and absorb water and nutrients from soil
B. A waxy cuticle, which prevents water loss
C. Colonial living, which maximizes use of resources while expending less energy
D. Stomata, which allow for gas exchange
2. Why is water needed for bryophyte reproduction?
A. Both the sperm and the egg develop in spores, which must swim through water to undergo fertilization.
B. The sperm must swim to the egg.
C. Without water, the sperm will fertilize the egg, but the embryo will not develop.
D. Without water, the embryo will remain haploid instead of diploid.
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2. Why is water needed for bryophyte reproduction?
A. Both the sperm and the egg develop in spores, which must swim through water to undergo fertilization.
B. The sperm must swim to the egg.
C. Without water, the sperm will fertilize the egg, but the embryo will not develop.
D. Without water, the embryo will remain haploid instead of diploid.
3. What is one of the main differences between club moss and moss?
A. Club moss has vascular tissue.
B. Moss has leaves; club moss does not.
C. To conduct water and nutrients, club moss has rhizoids rather than vessels.
D. Moss has sperm and egg within the same spore; club moss has them in different spores.
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3. What is one of the main differences between club moss and moss?
A. Club moss has vascular tissue.
B. Moss has leaves; club moss does not.
C. To conduct water and nutrients, club moss has rhizoids rather than vessels.
D. Moss has sperm and egg within the same spore; club moss has them in different spores.
What’s special about seeds?
Seeds allow the embryo to go dormant for a long period of hard conditions: cold or dry winters
Allows a wider range of dispersion
Seed coat
Endosperm
=Stored food
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Alternating Generations In more advanced plants, the sporophyte generation is dominant.
Alternation of generations modified
Pollen= Male gametophyte Contains sperm
Ovule= Female gametophyte Contains egg
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How is pollen an adaptation?
Allows fertilization to occur even in the absence of available water.
Moss fertilization
Pollen grains
water
Gymnosperms:“naked seed”
Coniferophyta (pines and cone bearing trees)
Cycads (palmlike)
Ginkgos (ginkgo trees)
Gnetophyta (gnetums)
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Gymnosperms: Ginkgo Long thought to be extinct in western civilization, until travelers from Germany found it while visiting temples in China and Japan.
Fleshy outer covering to seed–looks like a fruit
Cycads
Palm-like plants, but have cones for reproduction
Tropical
Endangered by poaching and a black market
Gymnosperms: Cycadophyta
23% of 305 extant
species endangered,
15% vulnerable
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Ephedra Welwitchsia Gnetum
• Flower-like structures
Temperate regions
except Australia Namibia Old and New
World Tropics
Gymnosperms: Gnetophyta
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Gymnosperms: Coniferophyta
Key characteristics:
Needle-like or scale like leaves
Thick cuticle
Recessed stomata
Resin
Cones
female
gametophyte
eggs
pollen
tube
haploid (n)
diploid (2n)
5
7
3
4
1 2
6
mature
sporophyte scale of a
female cone
scale of a
male cone
sperm
nucleus
embryo
seed
seedlings
female cone
male cone
spore-forming
cell
ovule
FERTILIZATION
MEIOTIC CELL
DIVISION IN
MALE SCALE
MEIOTIC CELL
DIVISION IN
FEMALE SCALE
Male cone
scales give rise to
pollen; each female
cone scale contains
two ovules
Pollen
is liberated
and carried
by the wind
Pollen lands
on the scale of a
female cone and
a pollen tube
begins to grow
As the pollen tube grows,
meiotic cell division in the ovule
leads to development of the
female gametophyte
When the pollen tube
reaches an egg within
the female gametophyte,
a sperm nucleus moves
through the tube and
fertilization occurs
The fertilized egg
develops into an embryo,
which is encased in a seed
The seed
germinates and the
embryo develops into
a sporophyte tree
Life Cycle of the Pine
Fig. 21-11
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Angiosperm specific adaptations
Unlike other plants they have: Flowers
Double fertilization
Fruit
What are the advantages of flowering?
Discuss this question in groups
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Angiosperms: the Flowering plants
Why do plants have flowers?
Enlists partnerships with insects and other animals
Less inbreeding
Higher probability the pollen will reach the right plant
They don’t have to produce as much pollen
Double fertilization 1. Two pollen nuclei enter ovule
2. One fuses with the egg to form the zygote
3. The other fuses with 2 central cell nuclei to become the endosperm (3n), food for the zygote
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Fruit development
Becomes the fruit! Becomes the seed!
anther
Flower ---> Fruit Progression
Apple
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Fruit: Form and Function Dispersal Mechanisms
Wind Animals
Maple seed
Milkweed Fleshy fruit
Acorn
Trends through Time
Gymnosperms
Angiosperms
Lycophytes
Pterophytes
Bryophytes
Ancestral Derived
Activity: Arrange the taxa below along the time
continuum, include shared, derived traits and examples
for each
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Trends through Time Ancestral Derived
Bryophytes
True mosses
Liverworts
Hornworts
Lycophytes Pterophytes
Club mosses:
Selaginella
Lycopodium
Whisk ferns
Horsetails
True Ferns
Gymnosperms Angiosperms
Conifers
Ginkophyta
Cycads
Gnetophyta
Monocotyledons
(monocots)
Dicotyledons
(dicots)
Non-vascular Seedless vascular
Seeds & Vascular
No Fruit Fruit
Trends through Time Ancestral Derived
Bryophytes
Gametophyte
dominant
Sperm - water
Pores
Waxy cuticle
Lycophytes Pterophytes
Sporophyte
dominant
Sperm - water
Vascular
tissue
Stomata
Stems
Leaves
Roots
Strobilus
Waxy cuticle
Sporophyte
dominant
Sperm - water
Vascular
tissue
Stomata
Stems
Leaves
Roots
Sori
Waxy cuticle
Gymnosperms Angiosperms
Sporophyte
dominant
Sperm-no water
Vascular tissue:
xylem-tracheids
Stomata
Woody stems
Seeds & Pollen
Waxy cuticle
Sporophyte
dominant
Sperm-no water
Vascular tissue
xylem-tracheids
phloem-seive
tube members
Seeds & Pollen
Flowers & Fruits Double fertilization
Waxy cuticle
Stomata
Non-vascular Seedless vascular
Seeds & Vascular
No Fruit Fruit