The notes seem very detailed and helpful since our lectures are all over the place!
9/11/2015 Soils & Plant Nutrition
Friday, September 11, 2015 12:22 PM
What challenges do plants face that animals do not? They cannot move when limiting factors become scarce. Most limiting
factor to most plant land growth: Nitrogen- they need it to make Rubisco from amino acids. To reproduce, they sometimes produce fruit that animals then spread the seeds of.
• What specializations do plants have to acquire needed resources? • How are resources shared throughout a plant?
Which partners help plants in acquiring nutrients? Mycorrhizae helps plants suck Nitrogen out of the ground. Rhizobacteria in We also discuss several other topics like Scientific and systematic study of politics, using methodology.
soil fix nitrogen from the air- especially in legumes.
• ? What is most of the weight in trees? Water from roots and gases in atmosphere
• Oxygen emitted from plant is the result of splitting of H2O, not CO2
• Know how different deficiencies affect plant health
• Limiting factors for plant growth
○ Sunlight, temp, water, competition, minerals, nutrients
• ? Most limiting factor needed for most plant land growth: Nitrogen
○ Important because they need it to make Rubisco from amino acids
○ If plants aren't fixing nitrogen, entire food source collapses Don't forget about the age old question of zoonutrients
○ The nitrogen travels through ecosystem in Nitrogen Cycle
• Nitrogen Cycle
Lightning can create high temp and pressure conditions in which N fuses and makes ammonia. We do this in
factories too (fertilizer)
○ Biological fixation, animals feeding on plants and their waste gets in soil
○ Nitrogen in the air is non-bio accessible (N2), we need NH4 (ammonia), NO2 (nitrite), and NO3 (nitrate)
Some bacteria can take gaseous nitrogen out of air and turn it into ammonia, they fix it in other ways too.
Microbes are responsible for converting N to different forms
○ Plants only use N as ammonia (NH4) and nitrate (NO3) … nitrite (NO2) is toxic to plants ▪ N2 --> NH4 --> NO2 --> NO3 --> N2O --> N2
○ We are consuming too many plants with our growing population! ○ If we run out of Nitrogen, we will have to make it using fossil fuels.
Haber Process: Produces ammonia directly from nitrogen and hydrogen under high pressure. Powered by
○ Plants get help from mycorrhizae to suck nitrogen out of ground, in return they give them sugars. • Rhizobia bacteria in soil fix nitrogen from air
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• Rhizobia bacteria in soil fix nitrogen from air
○ Symbiosis: they get fixed carbon (malate, sucrose) from the plant, plant gets biocompatible nitrogen ○ They especially work with legumes Don't forget about the age old question of ucr class
Leghemoglobin is found in root nodules, which acts as an oxygen trap. Which allows for bacteria to efficiently
fix nitrogen because they don't like oxygen.
? What is the source of leghemoglobin in plants? Ancient divergence of gene duplication and divergence.
Globin genes long time ago in common protistan ancestor? Could also just be horizotonal gene transfer?
How did bacteria and roots find each other? Plants excrete flavenoid molecules that chemically attract
▪ Bacteria binds to root hairs and enter tissue of plant thru infection thread.
▪ Lectin coats root hairs and recognizes specific rhizobacterium and lets them in
▪ Bacteria are making NodD genes, which activate the genes in plants to produce leghemoglobin If you want to learn more check out hericare
• The Nodulation Process
○ Chemical recognition of roots and Rhizobium
○ Root hair curling
○ Formation of infection thread
○ Invasion of roots by Rhizobia
○ Cortical cell divisions and formation of nodule tissue
○ Bacteria fix nitrogen which is transferred to plant cells in exchange for fixed carbon • Aquatic fern Azolla are symbiotic with cyanobacteria so it can fix nitrogen.
Palm Welfia regia has an epiphyllic relationship with cyanobacteria on its leaves. Bacteria transfer a % of N through leaf surfaces
• Some plants can do it themselves: carnivorous ones. Biology Page 2
9/14/2015 Carbon Cycle
Monday, September 14, 2015 12:21 PM
• How is carbon cycled among life on Earth? • In what forms is carbon bioavailable?
How have carbon dioxide levels varied during Earth’s history? How are levels varying now? It's been increasing exponentially in the last 200 yrs and is now increasing at 2ppm/yr.
• What mechanisms have plants evolved for acquiring carbon? C4 bundle sheath cells, stoma and guard cells • Is carbon a limiting factor for most plants?
IN THE NEWS: Why might your grandparents be celebrating with a glass of red wine? We also discuss several other topics like samantha swindell
It has Resveratrol, which is a polyphenol. It activates the SIRT1 gene that protects the body from diabetes and aging. Combats diabetes by preventing insulin resistance. Also combats Alzheimers by protecting nerve cells from buildup of plaque. Combats heart disease and cancer. Manufacturers are now selling resveratrol supplements with have extracts from a Japanese plant or red grapes. But the dosage in supplements have not been effective- too low. People would have to consume 58 L of red wine a day to get the good effects found in animal studies. New study says that low doses of resveratrol might be more effective than high dose. The mice that were pre-disposed to colon cancer did better with low doses than high.
• Carbon comprises less than 1/2 of 1% of the atmosphere (0.04%)
• Carboniferous Period lasted from 360-300 mya
There was more coal being made back then from all the trees whereas none is being made now. Why? There weren't termites or wood-digesting fungi back then.
Symbiosis in termites: termite eats wood and bacteria and protists inside its gut have enzymes that break wood down and produce fixed carbon products, which are returned to atmosphere.
• Atmospheric CO2 observatory on top of Mauna Loa in Hawaii ○ 2 ppm/yr increase of atmospheric CO2 We also discuss several other topics like james marcia (1966, 1993) expanded on erik erikson's psychosocial stages by focusing on two processes erikson deemed essential to achieving a mature identity. these two processes are:
There is more variability in the Mauna Loa data than the NZ data b/c there are more plants in the northern hemisphere so the CO2 output is greatly influenced by the seasons/photosynthesis.
• Where does atmospheric CO2 come from?
○ Petroleum, coal, natural gas, cement production, termite 'burps', cow farts ○ It's not necessarily all b/c of fossil fuels though….
HW: Other than the burning of fossil fuels, what other explanations can account for the exponential increase in atm. CO2 in the past 200 yrs?
Marine organisms pull out most of CO2 from atmosphere, so do terrestrial organisms and trees. Oceans absorb more CO2 than they release
• Plants get the CO2 out of the atmosphere b/c they have an enzyme with a high affinity for CO2: RuBisCO ○ Rubisco is most abundant enzyme
CO2 diffuses thru stomata primarily in leaves and rarely in stems. Stoma also release waste products and water vapor
Stoma surrounded by guard cells, whose cell walls can change shape depending on how much water they have. Advantageous: Retain water when they need it. Guard cells close to keep water in
○ Floating aquatic plants only have stoma on upper surface.
No stoma on fully submerged plants b/c they don’t worry about absorbing/losing water. They get CO2 directly thru diffusion of their thin leaves.
○ Henry's Law: C=kPgas
▪ C = the solubility of a gas at a fixed temperature in a particular solvent (in units of M or mL gas/L)
k = Henry's law constant (often in units of M/atm)
Pgas = the partial pressure of the gas (often in units of Atm)
▪ As the concentration of gas above solution increases, the concentration of that gas dissolved in solution Biology Page 1
As the concentration of gas above solution increases, the concentration of that gas dissolved in solution increases too
▪ As atmospheric levels of CO2 have increased, dissolved levels of CO2 has increased too ▪ CO2 is not the only thing that affects plant growth… temp does too
▪ Even though crop plants grow bigger under high CO2 conditions, they are less nutritional • C4 plants are more efficient at acquiring CO2
○ Mesophyll cells and bundle sheath cells
○ C4 metabolism has independently arisen several times from C3 ancestors
As we increase CO2, we increase temp. Higher temp and CO2 are beneficial to a point… but then photosynthesis decreases and plants are less nutritional
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9/16/2015 Carbon Cycle cont.
Wednesday, September 16, 2015 12:21 PM
• Commonly missed Exam 1 questions
○ Green algae has cellulose cell wall
○ Kdr mutations cause resistance to pyrethroids through A) Pump pyrethroids out of nerve cells as fast as it comes in. B) Break down pyrethroids as soon as it enters the nerve cell. C) Keep sodium channels in nerve cells open.
D) All of the above.
E) None of the above.
○ Chorophyll C is ONLY found in red algae!
Methane is powerful greenhouse gas on Earth that is almost always the product of anaerobic metabolism of bacteria and archaea (Ex: methane gut bacteria let out methane in animal waste)
• Clicker Question Largest source of methane in US: Livestock farming & fracking/coal mine leaks
Another source: rice farming. The flooded fields create anaerobic environments for methane bacteria.
Rice even has aerenchyma tissue to let methane out from the bacteria in soil thru their leaves. Aerenchyma is a spongy tissue that forms spaces or air channels in the leaves, stems and roots of some plants, which allows exchange of gases between the shoot and the root.
Volcanoes release a ton of CO2, but they are erupting at a steady rate over time. Miniscule compared
to fossil fuels
• Global Warming
○ Caused by CO2, methane, and other gases
Clicker Question: How do greenhouse gases lead to increased temps? Greenhouse gases temporarily absorb heat coming from land and water (infrared radiation that strikes Earth is reflected by gasses) ○
As molecules absorb infrared radiation the bonds bend and stretch (IR spectra). Most molecules in our atmosphere play no role in Greenhouse Effect b/c their bending/stretching patterns do not do not absorb IR at the proper energy level like CO2 does
Radiative Forcing: difference of radiant energy received by the Earth and energy bounced back to space
Water vapor has remained constant but CO2 and CH4 are responsible more most increase in IR absorption
For all human history the average rate of increase of CO2 is 1ppm/1000 yrs with a max rate of 1ppm/100 yrs. TODAY: 2ppm/yr. That’s 200x faster than the normal fastest rate of the last 1200 yrs.
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