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Botany Overview. 1st Remarks: “Plants Can’t Run” Plants have covered the globe. The basic information is usually the most important. What’s here?. Overview of plant evolution and plant clades Overview of plant growth and development Overview of Plant Transport Overview of Photosynthesis
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Botany Overview • 1st Remarks: • “Plants Can’t Run” • Plants have covered the globe. • The basic information is usually the most important.
What’s here? • Overview of plant evolution and plant clades • Overview of plant growth and development • Overview of Plant Transport • Overview of Photosynthesis • Overview of Plant Response to the Environment
What if you can’t run and you can’t eat? Major Balancing Act Major Challenge
Who are the Land Plants? Shared Primitive Characters: Shared Derived Characters: Table 29.1 (578)
Sporophyte changes as plants become more derived. Table 29.1 (578)
SOUTHERN COASTS "a vast forest of the most stately pine trees that can be imagined, planted by nature at a moderate distance. . . enameled with a variety of flowering shrubs." Fire defined where the longleaf pine forest was found and fostered an ecosystem diverse in plants and animals.
All Hail The Mighty Flower! • Beauty • Ingenuity • Dominance • Support • Evolution/Classification
Ingenuity 3: Double Fertilization What is a seed? What is a fruit?
Secondary Growth Initials!
Over all transport in Plants: Major Balancing Act Major Challenge 3 “transport regions”: xm: ctc: wp:
Transmembrane (xm) Transport: mediated by transport proteinsand “set up” by chemiosmosis (proton pumps) Membrane Potential
Results of a chemo-electrical gradient…good stuff for the plant
These cellular processes lead to whole plant transport(aka Bulk Flow) • Hydrostatic pressure pulls sap down • Tension pulls sap (water) up • Facilitated by changes in water potential between neighboring cells • Diffusion/Osmosis • Active Transport • Vessel structure leads to increased transport efficiency • Xylem: • Dead… • Phloem: • So what…
Accent of Xylem Sap: Differences in Water Potential! • Facilitated by the physical properties of water • Adhesion/Cohesion • Water molecules on the march!
Phloem Loading: Source-Sink Phloem Sap: 30% sugar (sucrose) by volume! Sugar Source: … Sugar Sink: …
Transpiration on a cellular level How does water move up to the leaves? It can be pushed… It can be pulled… How powerful is transpiration? Fig. 36.12 Page 747
Regulation of transpiration occurs at the stomata, thanks to… Structure and Function Are correlated Regulation of Stomatal Opening: K+ Transport & Turgor Pressure *Light *CO2 *Circadian Rhythms
Bioenergetics: Background Info • Producers • Consumers
Across four levels of organization • Plants • Leaves • Mesophyll Cells • Chloroplasts
Food for thought: How are cellular respiration and photosynthesis similar? How are they different? Think about it on an organismal level, on an organelle level, and on a biochemical level.
So What? • So what happens when light is absorbed? photosystem
No, really, so what? • Where does the electron from water go once it replaces the electron in the chlorophyll molecule in the center of PSII (PS 680)?
What do the Light Reactions produce? • Light Reactions…
Photosynthesis: The Big Picture Location Energy conversions Material inputs/outputs
Photorespiration • A drain on Calvin Cycle Energy that produces no ATP, it does produce CO2 • Why? Rubisco has an affinity for O2 • …and when [O2] build up in cells (and [CO2] drop)… • Rubisco binds RuBP to O2 instead of CO2 • Why? Rubisco evolved before O2 concentrations were appreciable in atmosphere • Can drain as much as 50% of photosynthetic energy away.
Fighting Photorespiration the C4 way • High Light, High heat (think Corn). • What happens when it gets too hot, and transpiration increases? • What happens to [CO2] and [O2]? • How do plants combat this? • Fix CO2 into PEP Carboxylase • (4-C compound) • Deliver 4-C compound to Calvin Cycle in Bundle Sheath (where [O2] are lower. • Perform Calvin Cycle in Bundle Sheath • Transport Sugars (Sucrose) to Phloem • Spatial Separation!
Fighting Photorespiration the CAM way • What are conditions like in the desert? • What will the stomata do? • How will the plants get CO2? • Open stomata at night! • Fix CO2 into organic acids (Crussalean Acid Metabolism) at night, store in vaculoles • During day, when light is available… • Temporal Separation!
Botany Overview • 1st Remarks: • “Plants Can’t Run” • Plants have covered the globe. • The basic information is usually the most important.
Why Study Plant Hormones/Plant Responses to the environment? • Ties into the theme: “Plants can’t run.” • Allows us to look at cellular (and sub-cellular processes) and relate them to organism function. • Gives us a glimpse of how organisms respond to stimuli and interact with an ecosystem (abiotic and biotic forces). • In a sense, this is physiological ecology