EXAM 1
What is the definition of adaptation?
Any heritable behavioral, morphological, or physiological trait that maintains or increases the fitness of an organism under a given set of environmental conditions
What are autotrophs and heterotrophs? Name some examples
Autotrophs produce their own energy from the sun: plants and Cyanobacteria Heterotrophs relying on consuming other organism for energy: animals
A forest has an LAI of 3 and has 1/2 of light reaching the forest floor. If the LAI increases to 4, what is the percentage of light that reaches the forest floor?
Basic Steps: % reaching floor=LAI(I0) Solve for I0 I0xnew LAI= % light not reaching floor Subtract from 1 to find % reaching floor 0.5=3(I0) I0=0.167 % not reaching=67% % reaching=33%
What are the sources of carbon, hydrogen and oxygen for plants? What about major mineral nutrients
Carbon and oxygen: air Hydrogen: water Nutrients: soil
What is the unit of natural selection?
Individual/Organism
Why do soils in the north and south differ in pH and color? Hint: Oxides of Fe are reddish-brownish in color while organic materials are dark in color
The southern soil has iron in it that is oxidized causing the reddish color and producing H+ as a byproduct when oxidized by water making the soil more acidic Northern soil is without iron but produces basic soil when water is added
How do you define "ecology"
The study of the structure and function of nature
What is albedo?
The fraction of incident radiation that is reflected by a surface or body
Which forest has a denser canopy: one with an LAI of 3 or 5?
5 Low LAI indicates more light reaching forest floor
What are the major greenhouse gases? (4)
1) CO2 2) CH4 3) Chlorofluorcarbons (CFC) 4) Nitrous Oxide (N2O)
What are the contributions to ecology by some of scientists mentioned in class? (8)
1)Carl Ludwig Willdenow and 2) Heinrich Alexander von Humboldt pointed out that regions of the world w/ similar climates support similar vegetation concluded form and function of plants reflect the constraints of their environment 3)Johannes Warming wrote the first book on plant ecology 4) Charles Darwin 5)Gregor Mendel 6)Henry C Cowles studied the succession of plant in Indiana sand dune established plant succession as a central concept of ecology 7) Rachel Carson environmentalist, got DDT banned, noted that poisons and pollutants recycled through environment; silent spring 8)Eugene P. Odum father of modern ecology
C4 plants were hypothesized to have evolved in response to a lower CO2 level in the atmosphere in the past. What is the CO2 level in today's atmosphere?
420ppm
What is the percentage of light that reaches a forest floor if LAI=0?
100%
How many total soil orders are there?
12
How do you calculate ground area?
2piR
What do 3PGA and OAA stand for?
3-phosphoglycerate Oxaloacetic acid
What is the fate of the incoming solar radiation?
About 50% is absorbed by surface of the earth; 30% reflected by atmosphere and surface; 20% absorbed by clouds
What are the major differences between C3, C4 and CAM plants?
C3 produce 3PGA during dark cycle C4 produce 4 carbon OAA during dark cycle - CO2 concentration + Calvin Cycle CAM 4 carbon OAA produced from PEP and CO2 at night, OAA converted to malic acid and stored in vacuoles during day malic acid diffuses out of vacuoles and converted to PEP and CO2 CO2 enters Calvin cycle
What are examples of C3, C4 and CAM plants?
C3: All Trees, wheat, grasses C4: corn, sugar cane, sorghum CAM: Cacti, orchids, crassula
What are the adaptive advantages of each photosynthetic pathway?
C3: More efficient than C4 and CAM under cool and moist conditions, require fewer enzymes and no specialized anatomy C4: photsynthesize faster under high light intensity and temperatures as CO2 delivered directly to Rubisco not allowing Rubisco to react with O2 and undergo photorespiration; better water use efficiency because PEP carboxylase brings in CO2 faster and so does not need to keep stomata open as much; evolved when CO2 is lower CAM: better water use efficiency than C3 under arid conditions due to opening stomata at night when transportation rates are lower
Do you expect the proportion of the total number of C4 species to increase or decrease if you walk from Texas northward?
C4 species decrease as you go north
What are the roles of CO2, H2O, and chlorophylls in photosynthesis?
CO2 and H2O react to produce glucose and water Chlorophyll absorbs light and converts it to chemical energy
What are the most important photosynthetic pigments? And what wavelengths do they absorb?
Chlorophylls (~400 and ~680) and Carotenoids (~500)
What are the characteristics and effects of La Niña?
Cold event; reverse of El Niño -droughts in US and Peru-warm winters in the south and cold winters in great lakes to pacific -excessive moisture in Australia, west Asia, and east Africa
What is photosynthesis?
Converting Carbon Dioxide and water to sugar and oxygen 6CO2 + 6H20=C6H12O6 + 6O2
How do you calculate relative humidity?
Current VP/Saturation VP
What enzymes are used in CAM during day and night
Day: Rubisco Night: PEP in same cell active at different times
What does a large difference between dew point temperature and current temperature mean?
Drier; if they are equal it is very wet
How is a rain shadow formed?
Dry area on mountain side due to evaporation of water on opposite side which is released at the top of the mountain where temperature is lower and unable to hold water in air as well any remaining water will be held in the air as temperature increases going down the side where the shadow forms
What is the origin of the term "ecology"
Eco=oikos means household or home; first coined by German biologist Ernst Haeckel
Do shade intolerant species have high or low LCP?
High need more light to photosynthesize
Be able to describe how water moves from soil to the leaves and to the atmosphere.
High water potential in soil moving from root to xylem to stem to branches to leaves to atmosphere where there is the lowest water potential stomata takes in CO2 and releases H20
Does the air hold more moisture at a higher or lower temperature?
Higher
Will humidity be higher or lower at low temperatures?
Higher
What is the Law of the minimum? Who developed this law?
If one nutrient is deficient, plant growth will be limited even though supplies of all essential elements are adequate; the most important nutrient is the one that is deficient; Justus Von Liebig
What is the law that can be used to describe light attenuation within a forest canopy or in an aquatic environment such as a lake?
Lambert Beer Extinction Law Iz=I0 x e^-kxLAI Iz=light reaching any vertical position in the canopy I0=radiation incident at the top LAI=cumulative lead area index above Z K=light extinction coefficient
What is LAI?
Leaf Area Index
What are light and dark reactions and where do they occur?
Light reactions occur in the thylakoids of the grana 1. Photolysis splits water molecules creating H+, electrons and oxygen gas 2. ATP is made 3. NADP+ reduced -> NADPH Dark reactions occur in the stroma 1. 6 CO2 combine with 6 RuBP (5 C) 2. 6 carbon complexes split into two 3PGA molecules 3. Each 3PGA converted to G3P 4. 10 of 12 G3P restructured to be 6 5C RuBP 5. Net gain of 2 G3P molecules= sugars for plant growth (Calvin Cycle)
What are some key characteristics of water?
Linked by hydrogen bonds Polar 70% of earths surface
If the light compensation point is greater than the amount of light will the plant gain or lose carbon?
Lose
What is transpiration?
Loss of water through stomata
What surrounds the bundle sheath?
Mesophyll Cells
What do some plants do to reduce the amount of water lost through transpiration during mid-day?
Midday depression reduce photosynthetic activity at the hottest point of the day when the most water would be required
What are the most important soil orders in the Midwest?
Mollisols: well-developed soils high in organic matter and calcium; very productive Alfisols: moist, moderately weathered mineral soils
Are the leaves of Crassula more or less acidic at night?
More acidic at night bc malic acid stored in vacuoles
What are the three types of C4 pathways and what are examples from each
NADP-ME: Corn, sorghum and sugar cane MOST IMPORTANT NAD-ME: PIgweed and millet PEP-CK: Guinea grass
how does a hydrogen bond form?
Oxygen atom is more electronegative than H so it pulls more than fair share of electrons creating a partial negative charge on oxygen and partial positive on H
know the photosynthetic light response curve well. Name the key points of the curve and what they tell us about photosynthetic responses?
PAR=0: no light-dark respiration Curve crosses x-axis: light compensation point CO2=O2 Curve plateau: light saturation point photosynthesis will not increase (x axis indicates maximum PAR unit for most photosynthesis) (y axis indicates greatest photosynthetic rate)
What are the differences between Rubisco and PEP carboxylase in terms of their adaptations to temperature?
PEP is better suited for hot temps because it brings in CO2 faster and does not keep stomata open
Describe the Carbon fixation process of C4 plants
PEP reacts with CO2 to make OAA in the mesophyll cell OAA converted to malic acid Malic migrates to bundle sheath cell converted to pyruvic acid and CO2 Pyruvic acid returns to mesophyll cells to form more PEP and CO2 enters Calvin cycle
What are the five major factors in soils formation?
Parent material (type of rock), climate, biota, topography, time (PCBTT)
What are the differences between photorespiration and dark respiration of plants? What purpose does each serve?
Photorespiration occurs in chloroplasts, peroxisomes, and mitochondria; can only happen when light is available; no obvious physiological function; absent in C4 plants and CAM; RuBP and Oxygen react with Rubisco to make PGA+ phosphoglycolate to make CO2 Dark Respiration provides energy for plant growth and maintenance and happen in living cells all the time; glucose to pyruvic acid to Acetyl-CoA in the cytoplasm then the Krebs cycle is done in the mitochondrial matrix and the electron transport system is carried out in the inner mitochondrial membrane Glucose+ O2 —> CO2 + H2O + ATP
Where do photorespiration and dark respiration happen inside a plant cell?
Photorespiration: chloroplasts, peroxisomes, and mitochondria Dark: cytoplasm and mitochondria
What is PAR? What is its range of wavelength?
Photosynthetically Active Radiation 400nm-700nm
What is the unit of evolution?
Population
What is a soil profile and what is a soil horizon?
Profile: a vertical cut through a body of soil Horizon: different layers of the soil including A, B and C A: organic B: subsoil C:mostly rocky
What is shoot/root ratio? How do plants adapt to different nutrient environments?
Root biomass/shoot biomass the ratio between a plants amount of roots to shoots In poor soil environment develop more roots in poor atmospheric conditions more shoots
What is the enzyme that catalyze the first step in the Calvin Cycle?
Rubisco
What is the most abundant enzyme on earth?
Rubisco
What is the relationship between temperature and saturated vapor pressure?
Saturation vapor pressure is a function of air temperature; the higher the temp, the higher the SVP
What does ecology study?
Science of interactions; the study of living organisms with their nonliving environment; biotic w/ abiotic
How does the greenhouse effect happen?
Some of the infrared radiation passes through the atmosphere but most is absorbed and re-emitted in all directions by greenhouse gas molecules and clouds; the effect of this is to warm the earth surface and lower the atmosphere; necessary to keep the earth temp at about 15C
If there are multiple canopies, how do you calculate LAI?
Sum of their leaf areas
What are the differences between chlorophyll a and b?
Their absorption spectra A-400 and 700 B-500 and 650
How do you calculate LAI?
Total leaf area/ground area
True or false all plant pathways contain calvin cycle
True
What is the relationship between vapor pressure, saturation vapor pressure, vapor pressure deficit and dew point temperature?
Vapor Pressure- the amount of pressure water vapor exerts independent of the dry air Saturation VP- the pressure that water vapor exerts when the air is moisture saturated Vapor pressure deficit= Saturation VP-Current VP Dew Point Temperature- the temperature at which saturation VP is achieved for a given water content of the air
How do you determine saturation vapor pressure?
Vapor pressure vs temperature; the more vapor pressure and higher the temperature the higher the saturation vapor pressure
What are the characteristics and effects of El Niño?
Warm event; Normally: High pressure zone in the eastern pacific (south america) and low pressure in western pacific (asia) the pressure difference drives trade winds from east to west Walker circulation; El Niño: trade winds relax and increase convection -Increased Rain in southern US and Peru -Droughts and fires in west pacific and Australia -Decreased fish etc. due to cold water not coming up and replenishing nutrients -Drought in east Africa reducing corn production
What green house gases are most important?
Water and CO2 for anthropogenic
