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30 Cards in this Set
- Front
- Back
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Energy |
ability to do work
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1st law of thermodynamics |
energy can not be created nor destroyed
energy transferred from one state to another
a.k.a law of conservation of mass |
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2nd law of thermodynamics |
when energy is transferred there will be less energy at the end of the process than at the beginning
Entropy increases as energy is transferred
a.k.a. law of entropy (lower = more order / higher = less order) |
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Sources of Energy |
Sunlight
Inorganic chemical compounds
Consumption of organic compounds |
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Forms of energy |
Radiant energy - sunlight
Chemical energy - stored in the bonds of food molecules
Kinetic energy - associated with movement of molecules; measured as temp. |
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Autotrophs |
assimilate energy from sunlight (photosynthesis), or from inorganic compounds (chemosynthesis)
energy converted into chemical energy stored in bonds of organic molecules |
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Heterotrophs |
obtain energy by consuming organic compounds from other organisms
energy originated with organic compounds synthesized by autotrophs |
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Autotrophy |
capture radiant & chemical energy is converted into stored energy in carbon - carbon bonds |
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Chemosynthesis |
energy from oxidizing inorganic compounds is used to produce carbohydrates
important in nutrient cycling bacteria & in hydrothermal vent communities |
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Calvin Cycle |
biochemical pathway to fix CO2
catalyzed by several enzymes
occurs in chemosynthetic and photosynthetic organisms |
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Chemosynthesizers nitrifying bacteria |
Nitrosomonas, Nitrobacter
convert ammonium (NH4+) to nitrite (NO2-), then oxidize to nitrate (NO3-) in the nitrogen cycle
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Chemosynthesizers sulfur bacteria |
use H2S and HS- (hydrogen sulfide) as an energy source
produce elemental S, which is used as e- source, producing SO4 2- (sulfate) |
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Photosynthetic organisms |
archaea
bacteria
protists
most algae and plants |
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Photosynthesis |
1.) Light reaction - light used to split H2O & free e- to make ATP & NADPH
2.) Dark reaction - CO2 fixed in Calvin Cycle & carbohydrates are synthesized |
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Types of incoming radiation |
Solar radiation (Visible light, Ultraviolet, Infrared)
Secondary long wave radiation |
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Influences on incoming radiation |
Atmospheric gas, dust, clouds, different energy frequencies
Seasonal effects, latitudinal effects, differential surface heating |
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Average net radiant energy reaching earth surface |
2 gcal / cm2 / min = solar constant |
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components of radiant energy reaching earth’s surface on a clear day |
45% Visible light (least affected by atmosphere)
10% Ultraviolet
45% Infrared |
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% fate of solar radiation entering atmosphere |
1% converted into food and other biomass
69% goes into heat/evaporation/wind (not lost —> optimize habitat)
30% reflected back to space |
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Influences on efficiency of photosynthesis |
1.) Environmental control on photosynthetic rates (light intensities)
2.) Water availability (stomates close, restricting CO2 uptake leading to energy accumulations and damaged membranes)
3.) Temperature (affects rates of chemical rxns and structure of enzymes/membranes)
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Photosynthesis pathways |
Environmental pressures has resulted in evolution of multiple photosynthesis pathways
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C3 photosynthetic pathway |
Rubisco catalyzes 2 rxns: 1.) Carboxylase rxn - associated with photosynthesis 2.) Oxygenase rxn - associated with photorespiration
Both rxns depend on temp. & O2:CO2 ratio
Photorespiration increases as CO2 concentration decreases and temp. increases
Thrive in areas where sunlight intensity and temperatures are moderate and carbon dioxide concentrations are high |
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C4 photosynthetic pathway |
Requires more ATP but higher photosynthetic efficiency gives these plants advantage at high temperatures and lower water conditions
Close correlation between temperature and proportion of C4 species in community (C4 plants dominate grass lands and deserts - warm and tropical climates) |
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Crassulacean acid metabolism (CAM) photosynthetic pathway |
CO2 uptake and calvin cycle are separated temporarily
Stomates open at night when cooler & humidity is higher (close during day)
At night, plants take up CO2 and a 4-carbon compound is made and stored in vacuoles
CAM plants often succulent, with thick fleshy leaves/stems and common in arid environments
Aquatic plants use CAM to facilitate CO2 uptake in aquatic environments (CO2 diffusion into wear is slow)
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Facultative CAM |
plants that switch between C3 and CAM
When water is abundant, C3 pathway is used (allows more carbon gain)
If conditions become arid or saline, they switch to CAM
Proportions of stable carbon isotopes in plant tissues indicate which photosynthetic pathway is used |
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Heterotrophy basics |
Consume organic compounds & convert into chemical energy
Energy gain depends on chemistry of food and effort used to find and ingest food |
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Fats vs. Carbs vs. Proteins converted to calories |
Broken down into a.a., simple sugars, and fatty acids
Fats = 9 calories/g Carbs = 4 calories/g a.a. = 4 calories/g |
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Variations in feeding methods available to heterotrophs |
Archaea, bacteria, and fungi excrete enzymes into environment to break down organic matter (digest food outside bodies)
Multicellular animals evolved specialized tissues and organs for assimilating energy (Insects - various appendages and mouthparts; Birds - variation in mouthparts/bills) |
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Optimal foraging theory |
animals will maximize the amount of energy gained per unit time, energy, and risk involved in finding food
assumes evolution acts on behavior of animals to maximize energy gain
profitability of food item (P) depends on how much energy (E) the animal gets from the food relative to time (t) spend obtaining food P=E/t
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Breakdown of human primary production use |
4% of terrestrial net production used directly by humans / domestic animals
34-41% tied up in non-edible production
developed countries produce 4x more crop yield than underdeveloped countries (but 65% of population is in underdeveloped countries)
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