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-Read pg. What is your circadian rhythm?. Fill out circadian rhythm sheet. Biological Clocks/Circadian Rhythms. A physiological cycle with a frequency of about 24 hours is called a circadian rhythm
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-Read pg. What is your circadian rhythm? Fill out circadian rhythm sheet
Biological Clocks/Circadian Rhythms • A physiological cycle with a frequency of about 24 hours is called a circadian rhythm • Even without external, environmental cues, circadian rhythms persist in humans and in all eukaryotes • Example: jet lag in humans
Photoperiodism • A physiological response to day length (differs in winter, summer, spring, and fall) is known as photoperiodism • Short-day plants • Require a shorter light period • Flower in later summer/fall/winter • Example: poinsettias • Long-day plants • Require a longer light period • Flower in late spring/early summer • Example: spinach • Day-neutral plants • Are unaffected by photoperiod • Example: tomatoes • But it’s actually the night that matters!!
Plant Hormones • Hormones are chemical signals that coordinate the various parts of an organism • A hormone is a compound produced in one part of the body which is then transported to other parts of the body, where it triggers responses in target cells and tissues • Examples of human hormones: • Adrenaline, testosterone, estrogen, epinephrine…
Plant Hormones • There are 5 major classes of plant hormones, each with specific functions: • Auxin • Cytokinins • Gibberellins • Abscisic acid • Ethylene
Auxin • Stimulates stem elongation • Stimulates development of fruit • Involved in phototropism and gravitropism
Cytokinins • Stimulate cell division and growth • Stimulate cytokinesis • Stimulate germination and flowering
Gibberelins • Trigger seed and bud germination • Promote stem elongation and leaf growth • Important in the growth of fruit
Ethylene • Promotes fruit ripening • Senescence (aging) is a progression of irreversible change that eventually leads to death • Caused, at least in part, by ethylene • “One bad apple spoils the whole bunch”
Abscisic Acid • Induces seed dormancy • Anti-gibberellin • Inhibits cell growth • Anti-cytokinin • Inhibits fruit ripening • Anti-ethylene • Closes stomata during water stress, allowing many plants to survive droughts
Tropisms • Tropisms are growth responses that result in curvatures of whole plant organs toward or away from a stimuli • There are three major stimuli that induce tropisms • Light (Phototropism) • Gravity (Gravitropism) • Touch (Thigmotropism)
Phototropism • Phototropism is the growth of a shoot towards light • This is primarily due to the action of auxin • Auxin elongates the cells on the non-light side
Plant Defenses • Plants defend themselves against herbivores in several ways • Physical defenses, such as thorns • Chemical defenses, such as producing distasteful/toxic compounds
interactions between root, stem, leaf, • flower color based on pH
To do #1 -Make a list of plant hormones and their functions -Compare circadian rythm, phototropism, and photperiodism
Fungi and Plants http://www.wisc-online.com/objects/ViewObject.aspx?ID=BIO304
Fungi--Nutrition and Habitat - Decomposers/Absorptive heterotrophs - saprobic, parasitic, mutualistic
Classification of Fungi Chytridiomycota - uniflagellated spores - link to protists? Zygomycota - zygosporangia - black bread mold (Rhizopus stolonifer) Asomycota - spores produced in asci (sac-like structure) - truffles (Tuber melanosporum) Basidiomycota - spores formed in basidiocarps - mushrooms
Structure - hyphae form mycellium
Above: The common mold Rhizopus decomposing strawberries Right: Pilobolus aiming its sporangia. Pilobolus, the hat thrower. Pilobolus is a dung-loving (coprophilous) fungus. Spores are dispersed up to 2 m away and stick to grass blades in the vicinity. The grass and caps are eventually eaten by herbivores.
Life cycle of bread mold WATCH--http://bcs.whfreeman.com/thelifewire/content/chp31/31020.html Use these 10 terms to explain the life cycle of a bread mold • Hyphae • Sporangia • Spore • Asexual • Sexual • Pheromones • Zygosporangium • Nuclei • Haploid • Diploid
Fungal gills, Hypholoma fasciculare (Basidiomycota). The gills hang down from the cap in a tightly packed array. By producing gills in this way the mushroom can increase the surface area of the fertile layer (hymenium) by a factor of 20 or more.
Molds, Yeasts, Lichens and Mycorrhizae - represent unique lifestyles that evolved independently Molds Penicillium on an orange, soft rot of citrus. The name Penicillium comes from penicillus = brush, and this is based on the brush-like appearance of the fruiting structure under the microscope.
Yeasts - unicellular fungi that inhabit moist habitats - Saccharomyces cerevisiae - baker/brewer yeast - Candida - inhabit human epithelial tissue - AIDS patients
Lichens - symbiotic association b/n fungi and algae - mutual exploitation - tough, resistant; but sensitive to air pollution
Mycorrhizae - mutualistic associations with plant roots - increases the absorptive surface area of plant roots - exchange of minerals between plant and fungus
To do #2 -Watch life cycle of a bread mold -Write a summary of the life cycle of bread mold