Download Sampling methods Sampling Daphnia Sampling Hydra

Sampling methods
ƒ Daphnia
ƒ Random samples with a smaller collection beaker
ƒ 50 ml
Sampling Daphnia
Sampling Hydra
Recombinant DNA is DNA taken from two different sources and fused into a single
DNA molecule. Special DNA cutting enzymes, called restriction enzymes, cut the DNA
at specific sites.
ƒ Recombinant DNA technology has extensive applications in
developing pharmaceuticals.
ƒ The first drug created using recombinant DNA was human insulin.
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Need a restriction enzyme that will cleave known segments of DNA
Restriction enzymes specific for organism
DNA fragment migration through the gel dependent upon fragment size
Bands do not represent genes
• Miller and Urey experiment
• Early earth conditions
– No oxygen
– SH2 gas
– NH3
– CH4
• fossil evidence refutes findings
• Environment was not conducive to life originating from the primordial liquid
– Bubble model proposes key chemical processes generating the building
blocks of life took place within bubbles on ocean’s surface.
• Before 1.7 billion years ago, only prokaryotes found in fossil record.
– First microfossils (eukaryotes) appear in fossil record 1.7 billion years ago.
Evolution of Plants
Chapter 16
Outline
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Adapting to Terrestrial Life
Vascular Plants
Seedless Vascular Plants
Seed Plants
– Gymnosperms
– Angiosperms
• Flowers
– Dicots and Monocots
– Seed Dispersal
Adapting to Terrestrial Living
• Green algae (Charophyceans) that were probably the ancestors of today’s
plants are aquatic organisms not well-adapted to living on land.
– Had to overcome three challenges:
• Minerals absorption from rocky surfaces
• Water conservation
• Reproduction on land
Adapting to Terrestrial Living
Adapting to Terrestrial Living
• Mineral Absorption – symbiotic fungi
– Plants require relatively large amounts of six inorganic minerals:
• Nitrogen, potassium, calcium, phosphorus, magnesium, and sulfur.
– Mycorrhizae
Adapting to Terrestrial Living
• Water Conservation
– Cuticle - watertight outer covering.
• Stomata - gas and vapor exchange.
Adapting to Terrestrial Living
• Reproduction on Land
– Due to immobility, gametes must avoid drying while they are transferred
by wind or insects.
• Spore Development
– Generation alteration
• Sporophytes - diploid generation
• Gametophyte - hapolid generation
Evolution of Vascular System
• Terrestrial plants are required to carry water up from roots to
leaves, and carbohydrates down from leaves to roots.
– Vascular System
• Specialized strands of connected
hollow cells.
– Nine of Twelve living plant phyla are vascular.
Nonvascular Plants
• Only two phyla of living plants lack a vascular system:
– Liverworts (Hepaticophyta)
– Hornworts (Anthocerophyta)
• Simple semi- Vascular Systems
– Mosses were first plants to evolve strands of specialized conduction cells.
• No specialized wall thickening.
Evolution of Vascular Tissue
• Appeared approximately 430 mya.
– Grew by cell division at the tips of stem and roots (Primary Growth).
• About 380 mya vascular plants developed a growth in which a cylinder of
cells beneath the bark divides, producing new cells around plant’s periphery
(Secondary Growth).
– Necessary for tall trees with thick trunks.
Leaf Vascular System
Vascular tissue
Vascular tissue – secondary growth
Seedless Vascular Plants
• Most abundant of the four phyla of seedless vascular plants contain
ferns with about 12,000 living species.
– Have both gametophyte and sporophyte individuals, each independent
and self-sufficient.
• Gametophyte produces eggs and sperm.
• Sporophyte bears and releases hapolid spores.
Seed Plants
• Seed - Embryo cover that offers protection of embryonic plant at its most
vulnerable stage.
– Male and Female gametophytes
• Male - microgametophytes (pollen grains) arise from microspores.
• Female - megametophytes contain eggs and develop from megaspores produced within ovule.
– Pollination - transfer of pollen.
Land plant phylogeny