LIFE 103 Wek 7 Ntes
LIFE 103 Wek 7 Ntes 103
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This 6 page Class Notes was uploaded by email@example.com Notetaker on Sunday March 6, 2016. The Class Notes belongs to 103 at Colorado State University taught by Tanya Dewey in Winter 2016. Since its upload, it has received 32 views. For similar materials see Life 103- Biology of Organisms in Biology at Colorado State University.
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Date Created: 03/06/16
Week 7 Notes Turgid- the cell membrane is pushed against the cell wall When plants wilt, it’s caused by lack of water, because to water also provides structure for plants Permanent wilting point point of no return. The plant will not rebound Aquaporine -Transport proteins -In the cell membrane, and their function is let water through and restrict solutes coming in Rate of water movement is regulated by phosphorylation of aquaporine proteins. Transport control -compartmental structure -Plasma membrane regulates which molecules enter -vascular membrane regulates transport between cytosol and vacuole Water and sugars -The cytosol and cell wall are continuous -Symplast cytoplasmic continuum -Plasmodesmata cytoplasm of neighboring cells is connected by channels -Apoplast continuum of cell walls and extracellular spaces -Transmembrane route through apoplast and symplast route Routes Symplastic route via cytosol Apoplastic route via cell walls and extracellular spaces Long distance -Bulk flow movement of fluid driven by pressure -Water and solute move through tracheids and vessel elements of xhylem and sieve-tube elements of phloem Absorbing water -root tips where water and minerals are absorbed -root hairs increase surface area -water crosses the cortex via symplast or apoplast Endodermis -Inner layer in root cortex -Around the vascular cylinder -Last stop for passage of minerals to enter the vascular tissue Casparian strip -waxy -has an endodermal wall that doesn’t allow apoplastic transfer into the vascular cylinder Bulk flow is driven by negative pressure in the xylem Xylem sap bulk flow replaces water loss -sap is pulled by roots and pushed by leaves What causes root pressure? -During the night, the root cells put mineral ions into the vascular cylinder xylem and lowers water potential Root pressure -water flows in from the root cortex -Roots have greater pressure than leaves Guttation excess water forms as droplets on tips of leaves Positive root pressure -weak -slightly aids in bulk flow of xylem Negative leaf pressure -Results due to transpiration -the negative pressure pulls on water that’s in the xylem -water is then pulled into the leaf Hydrogen bonds link water together. Adhesion allows water to “stick” to surfaces, preventing gravity from pulling water back down Stomata -account for the majority of water loss, up to 95% -3 cues 1. Light increases the uptake of potassium 2. decrease of carbon dioxide in leaf 3. internal clock (circadian rhythm) How stomata open -potassium goes into cell and water flows in to close -potassium goes out of cell and water goes out Desert adaptations -reduced leaves= fewer stomates -CAM CAM -at night, the stomata open -carbon dioxide is stored as malmate -majority of CAM species are angiosperms, but can also be ferns, gymnosperms, and monocots Sugar source to sugar sink -sugar source leaves produce the majority of sugars used by the plant -sugar sink consumers of sugar, tend to be bulbs or tubers -The season also determines what is a sink and source. In the summer, leaves are sugar sources. But in the winter, the leaves die. Now storage organs are sugar sources Sugar movement -moves via sieve-tube elements -can move symplastic and apoplastic -needs a cotransporters Water gets pulled by companion cell and phloem Xylem negative pressure. Bulk flow Phloem positive pressure Phloem -electrical signaling occurs in the phloem -moves macromolecules and some RNA through plasmodesmata Soil and nutrition Fragile ecosystem -top layer gives water and nutrients to plants -Organisms that live in the soil. Plants, bacterial, Insects, fungi, and nematodes Soil stratification -layers known as horizons -topsoil uppermost layer Smallest molecule to largest Clay silt sand Topsoil has living and dead organism and minerals and humus Loams -combo of silt, sand, and clay -very productive for plant growth A horizon topsoil. Living and decaying things are here B horizon less weathered rock C horizon parent material, and partially broken rock Inorganic -cations (potassium, calcium, magnesium) adhere to anion -prevents leaching Cation exchange cations are displaced by other cations Root hairs have an affinity for negative ions Acid rain -increases the proton concentration in soils. -important cations are dislodges -rain leaches the important nutrients Nitrogen oxide -fossil fuels Sulfur dioxide -Burn coal. When comes into contact with water becomes sulfuric acid Soil conservation Agriculture impacts -decrease nutrients -increase erosion -strains water -soil compaction Ogalla Aquifer -formed during the Ice Age and by glaciers -Aquifers near coasts are becoming saline. Fresh water sits on top of salt water, but we’ve tapped into that resource too much Pivot irrigation -minerals in water don’t evaporate and land becomes salty Drip irrigation -use less water and a decrease in salt Australia -2.5 million hectares are salinized. Fertilization -replaces lost minerals -Commercial fertilization adds nitrogen, phosphorous and potassium -Organic fertilization is manure, fish meal and compost -Natural fertilization is letting fields go fallow and doing crop rotations Modern agriculture -monoculture -fertilizer and bacteria dominated Control erosion -wind and water erode away topsoil -loss of nutrients -contour plowing -Use windbreaks -terracing hillsides -no till Nutrients -elements needed in order for a plant to finish their life cycle Macronutrients 9 that plants need in large amounts Carbon, oxygen, hydrogen, phosphorous, sulfure, potassium, calcium, magnesium, nitrogen Micronutrients plants need thsese only in small amounts Iron, manganese, boron, zinc, nickel, copper Rhizosphere- soil bound to roots -high microbial activity -roots secrete sugars, amino and organic acids Co-evolutionary relationship between plants and bacteria Rhizobacteria -free living -function in the rhizosphere -have the ability to enter roots -stimulate plant growth by making hormones -protect roots from disease by making antibiotics -make nutrients available Inoculation of seeds with rhizobacteria increases crop yields Bacteria and the nitrogen cycle 1. Nitrogen is in the athmosphere 2. Nitrogen goes into nitrogen fixing bacteria and organic material goes into ammonifying bacteria 3. Both the nitrogen fixing bacteria and ammonifying bacteria produce NH3 4. H+ from the soil makes NH4 5. NH4 can be used by plants 6. Nitrifying bacteria take NH4 and convert it to NO3 7. Denitrifying bacteria take NO3 and put N2 back into the atmosphere Legume roots -nodules infected with bacteria -bacteroids are in root nodules -bacteria give N2 and get sugar from plant Reproduction of angiosperms -pollen tube fertilizes egg -2 sperm go into the ovule -2n zygote grows into an embryo -ovary walls mature into a fruit -seed coat comes from integument which comes from the sporophyte (grand parents) -sperm comes from the parental generation Microsporangium -microsporocyte is 2n -4 microspores after meiosis n Megasporangium -megasporocyte is 2n -meiosis 1 n megaspore -mitosis 3 antipodal, 2 polar nuclei, egg, 2 synergids 2 polar nuclei + sperm= 3n endosperm 1 egg + 1 sperm = 2n zygote Zygote divides and terminal end grows Basal cell orientates the growing embryo Plant sexuality -angiosperms can be sexual and/or asexual -sexual= genetically different -asexual= can result in a clone Fragmentation separations of a parent plant into parts that eventually develop into a plant Parent root system give rise to adventitious shoots Apomixis asexual reproduction of seeds from diploid or haploid cell Forms of apomixes Nonrecurrent haploid gametophyte leads to a haploid individual Recurrent meiosis is not completed Adventive embryo arises from integument Vegetative flower replaced by a bulb Vegetative reproduction -asexual -beneficial for a successful plant -clones vulnerable if there’s a change in environment
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