Ecology exam 1
How does a hydrogen bond form in water?
A slightly positive charge of a hydrogen atom forms a weak bond with a slightly negative charge of a oxygen
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 is dew point temperature?
The temperature at which saturation VP is achieved for a given water content of the air
The study of ecology as it pertains to populations investigates what specific process?
evolution
What contributions to ecology were made by Gregor Mendel?
father of genetics; studied the transmission of characteristics from one generation to the next in pea plants
What contributions to ecology were made by Eugene P. Odum (1913-2002) ?
father of modern ecology
In terms of potential, which direction does water movement occur in a plant?
from high potential to low potential
What contributions to ecology were made by Johannes Warming (1841-1924) (and Christensen Raunkiær)?
he studied tropical forests in Brazil, and wrote the first book on ecology (Plantesamfund)
What contributions to ecology were made by Charles Darwin?
he theorized on natural selection and evolution, and wrote The Origin of Species
What are the adaptive advantages of CAM plants?
highest water use efficiency because stomata open at night (when transpiration rates are lower)
What are the characteristics of La Nina?
occurs after some el nino events; characterized by colder water in central and eastern tropical Pacific
What are the five major factors in soils formation?
parent material (the mass where soil forms), climate (radiant energy and water), topography (affects climate), biota (vegetation, animals, bacteria and fungi), time
What are the differences between photorespiration and dark respiration of plants?
photorespiration can only happen when light is available and has no obvious physiological function, and happens only in C3 plants; dark respiration can happen any time
What is the purpose of photorespiration? What is the purpose of dark respiration?
photorespiration has no obvious function; dark respiration provides energy for plant growth and maintenance
What are the adaptive advantages of C4 plants?
photosynthesis occurs faster than C3 under high light intensity and high temperature (CO2 is delivered directly to rubisco, and it can't react with oxygen), have better water use efficiency (WUE) (because PEP carboxylase brings in CO2 faster and does not need the stomata open as much), evolved when CO2 was lower than today's CO2 level
What is photosynthesis? What are the roles of CO2, H2O, chlorophylls in photosynthesis?
photosynthesis produces glucose and oxygen from CO2, light and water;
What is PAR? What is its range of wavelength?
photosynthetically active radiation (amount of light available for radiation) in umol m-2 s-1, 400-700 nm
When calculating ground area, if given radius, how is it calculated?
pi x r squared
What is albedo?
The fraction of incident radiation that is reflected by a surface or body (on a smoother surface, more light is reflected, and a higher percent of albedo results)
What is saturation vapor pressure?**
The pressure that water vapor exerts when the air is moisture saturated (can hold no more water) (as air gets colder, it is able to hold on to less moisture as vapor and it turns to liquid form)
Which forest has a denser canopy, one with an LAI of 3, or one with an LAI of 5?
5
What are the most important photosynthetic pigments?
chlorophyll a and chlorophyll b
What are the major steps in light reactions? (3 steps)
1. Photolysis takes place on the inside of the thylakoid membrane (photolysis is the splitting of water molecules in H+, electrons, and oxygen gas) 2. Energy-storing molecules ATP are created 3. NADP+ plus H+ plus e- form NADPH
What are the major steps in dark reactions? (5 steps)
1. Six molecules of CO2 combine with 6 molecules of ribulose 1,5-biphosphate (RuBP, 5-carbon) 2. Each 6-carbon complex is immediately split into two 3-carbon molecules, 3-phosphoglycerate (3PGA) 3. Each 3PGA is converted to one molecule of glyceraldehyde 3-phosphate (G3P) 4. Ten of the twelve G3P molecules are restructured and become 6 5-carbon molecules of RuBP 5. There is a net gain of 2 G3P molecules for sugars for plant growth
What is the percentage of light that reaches a forest floor if LAI=0?
100%
What do 3PGA and OAA stand for?
3-phosphoglycerate, oxaloacetic acid
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?
40%
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?
410 ppm
What is the approximate concentration of CO2 in the atmosphere today? What was it before the Industrial Revolution?
410 ppm; 280 ppm
What are the sources of carbon, hydrogen and oxygen for plants? What about the major mineral nutrients?
C, H, and O are derived from water and CO2; the major mineral nutrients (N, P, K, Ca, Mg, S) exist in varying concentrations in soil and water depending on the region
What are the major differences between C3, C4 and CAM plants?
C3 plants: produce 3-carbon PGA during the dark reactions (have C3 pathway only) C4 plants: produce 4-carbon OAA instead of 3-carbon PGA; have more developed bundle sheath cells CAM plants: 4-carbon OAA is produced from CO2 and CO2 by PEP carboxylase at night, rubisco during the day
What two scientists idea's provided the mechanisms for understanding the link between organisms and their environment (the focus of ecology)?
Darwin and Mendel
What contributions to ecology were made by Rachel Carson?
Did more than anyone else to bring environmental problems to the attention of the public; led to the ban of DDT in the US
What is the origin of the term "ecology"? How do you define "ecology"?
Greek word meaning home, defined as the study of the structure and function of nature
How do plants adapt their root to shoot ratio to different nutrient environments?
Higher root biomass allows for compensation if there is low nutrient availability
What is LAI? How do you calculate LAI?
LAI is a dimensionless measure of the amount of leaf cover, LAI=total leaf area (meters squared)/ground area (meters squared)
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 (Beer's Law)
What are light and dark reactions and where do they happen in a plant cell?
Light and dark reactions are the two steps of photosynthesis, light reactions occur in the thylakoids and dark reactions occur in the stroma
What are the differences between Rubisco and PEP carboxylase in terms of their adaptations to temperature?
PEP carboxylase is active at night (in cooler temperatures when stomata are open in CAM plants), while rubisco is active during the day (in higher temperatures when stomata are closed in CAM plants)
What is the vapor pressure?
The amount of pressure water vapor exerts independent of the dry air.
What are the characteristics of El Nino?
a disruption of the normal Pacific ocean and atmosphere; occurs around Christmas; normal western trade winds (Walker circulation) weaken and cause warmer surface water on the eastern Pacific
What are some greenhouse gases? Which ones are the most important?
a gas that contributes to the greenhouse effect; water vapor (most important, 3/4), carbon dioxide (most important human made greenhouse gas, 1/2 of human effect), methane, chlorofluorocarbons, nitrous oxide
What is a soil profile and what a soil horizon?
a vertical cut through a body of soil; a soil horizon is a horizontal cut
What is the fate of the incoming solar radiation?
about 50% is absorbed by the surface of the earth, and the rest is absorbed or reflected by the atmosphere, or reflected by Earth's surface
How is a rain shadow formed?
as elevation increases up a mountain, air gets colder and can hold on to less moisture, resulting in condensation; down the other side of the mountain, air can hold more and more moisture so it extracts it from the soil (resulting in an arid climate on that side)
What are autotrophs and heterotrophs? What are some examples of each group?
autotrophs carry out photosynthesis, heterotrophs consume autotrophs
What is an example of a CAM plant?
cacti (orchids, crassula)
What are the differences between chlorophyll a & b?
chlorophyll a is the primary photosynthetic pigment, chlorophyll b is the accessory pigment that passes energy to chlorophyll a; chlorophyll a absorption spectra peaks at slightly lower and slightly higher wavelengths of light
What are some key characteristics of water?
cohesion (lets water be pulled up roots), expands when freezing
What is an example of a C4 plant?
corn (sugar cane, sorghum)
What is the formula for relative humidity?
current vapor pressure/saturation vapor pressure
Where do dark reactions happen inside a plant cell? Where does photorespiration happen inside a plant cell?
dark reactions happen in the cytoplasm, mitochondrial matrix and mitochondrial inner membrane; photorespiration happens in chloroplasts, peroxisomes and mitochondria
Do you expect the proportion of C4 species to the total number of species to increase or decrease if you walk from Texas northward?
decrease
When the difference between temperature and dew point is bigger, is the air drier or wetter?
drier
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; Justus von Liebig
What are the effects of El Nino? (You should be able to tell El Nino and La Nina events from either an SST or SST anomaly graph).
majorly increased rainfall along eastern Pacific (flooding), decreased rainfall along western Pacific (drought, decreased corn harvest in East Africa), decline in fish and bird population along the Pacific shore of the Americas (because upwelling of nutrient rich cold water is suppressed),
What is an example of a C3 plant?
maple tree (oak tree, wheat, any tree)
What are the most important soil orders in the Mid-west?
mollisols (Well-developed soils high in organic matter and calcium; very productive) and alfisols (moist, moderately weathered mineral soils)
What are the adaptive advantages of C3 plants?
more efficient than C4 and CAM plants under cool and moist conditions, and under normal light; requires fewer enzymes and no special anatomy (most plants are C3 plants)
The study of ecology as it pertains to individuals investigates what specific process?
natural selection
Explain the photosynthetic light response curve well, esp. the key points in the curve and what they tell us about photosynthetic responses. Here, list the points that you must know.
rate of dark respiration point, light compensation point, light saturation point, light saturated (maximum) photosynthetic rate
What is shoot/root ratio?
root:shoot ratio= root biomass/shoot biomass
What is vapor pressure deficit?
saturation VP - current VP
How and why do soils in the north and the south differ in pH and in color? (Hint: Oxides of Fe are reddish-brownish in color, while organic materials are dark in color.)
soil is the north is closer to neutral/basic, soil in the south is generally more acidic because there is greater rainfall (which leaches away alkaline elements of soil)
How does the greenhouse effect happen?
some infrared radiation passes through the atmosphere, but most is absorbed and re-emitted in all directions by greenhouse gas molecules and clouds; warms Earth's surface (keeps it at around 15 deg C) and lower atmosphere
What contributions to ecology were made by Henry Cowles?
studied succession of plants on Indiana sand dunes and established plant succession as one central concept of modern ecology
What does ecology study?
the interactions of organisms with their biotic/abiotic environment
What has been happening to the strength and frequency of el nino events since the second half of the 20th century?
they are getting stronger and more frequent
What has been happening to the strength and frequency of la nina events since the second half of the 20th century?
they are getting weaker and less frequent
What contributions to ecology were made by Carl Ludwig Willdenow (1765-1812) and Heinrich Alexander von Humboldt (1769-1859)?
they found that regions with similar climates supported similar vegetation, and concluded that form and function of plants within a region reflected constraints of the physical environment
What is transpiration? What do some plants do to reduce the amount of water lost through transpiration during mid-day?
transpiration is loss of water through stomata (driving force for water uptake); some plants close their stomata to some degree during midday, or they can change their allocation patterns (where they put their biomass resources, root vs. shoot) to grow more roots
What are the effects of La Nina? (You should be able to tell El Nino and La Nina events from either an SST or SST anomaly graph).
warm winter in southeastern US, cold winters in Great Lakes to Pacific Northwest, excessive dryness in Americas, excessive wetness in Australia and western Pacific
Describe how water moves from soil to the leaves and to the atmosphere.
water flows from an area of high potential (soil) to an area of low potential (leaves); water is lost to the atmosphere because the air inside the leaf is usually around 99% humidity, which in turn decreases the plant's water content in the leaves and creates a water potential gradient