Exam 2 Lecture Slide Content Flashcards
HYPOTHESIS, TESTING, & THE SCIENTIFIC PROCESS
What is a theory?
A theory is a broad, yet concise explanation for a wide range of phenomena. Often the generalized product of many hypotheses. Ex.) plate tectonics, natural selection
What are some characteristics of a theory?
-Reinforced and updated by a wide range of experiments and observational studies
-Predictive
What is a hypothesis?
A proposed explanation for a relatively narrow set of phenomena (ex.) addition of amendments to soil will have a significant and positive effect of plants ability to uptake lead)
What is a characteristic of hypothesis?
-Based on background info and/or initial observations
-Specific
-Testable
-Focused
What is the difference between the null and alternative hypothesis?
Null- there is no relation between variables
Alternative- there is a significant relation between variables
In regards to scientific testing, what is the difference between evidence and an argument?
-Expectation + Observation = Evidence; Evidence lends support to help refute without “confirming” with certainty
-Background Information+Expectation+Observation= Argument; Arguments can lead to the support, rejection, revision, or replacement of a Hypothesis
In regards to scientific testing, what is the importance of control?
Controlling variables is paramount in minimizing potential for error or interference between variables
In regards to scientific testing, what is the importance of assumptions?
Assumptions are fundamental in conducting experiments as they allow us to believe in the certainty of specific actions taking place
What are some ways that ideas and hypothesis are shared within the scientific community?
Peer review, replication and discussion, eliminating bias, feedback for publication
SOILS
What the five factors of soil formation?
Organisms, Topography, Time, Climate, Parent Material
What are the Soil Horizons in order?
-O Horizon (Loose and partly decaying organic material)
-A Horizon (Mineral matter mixed with some humus)
-E Horizon (Eluviation layer; zone of leeching)
-B Horizon (Accumulation of minerals transported from above)
-C Horizon (Partially altered parent material)
-R Horizon (Unweathered parent material Bedrock)
What are the three classes of soil?
Sand, Silt, Clay
How does particle size vary between the three soil classes? How do these particle sizes effect water retention in each class?
-Sand has the largest and grittiest particles
-Silt has the medium-sized smooth particles
-Clay has the smallest and stickiest particles
-Too much sand means that there is no small pores and no water retention, but too. much clay means that there is no large pores and no water drainage; happy medium is best for water retention!
In regards to water retention, what is the difference in gravitational water, capillary water, and hygroscopic water?
-Gravitational water: water that drains right through the soil
-Capillary water: water remaining in the soil that is readily available for plants
-Hygroscopic water: Remaining water that is held too tightly for plants to draw
What are the four pools of plant nutrients?
-Soil minerals (naturally occurring inorganic solids, major source of soil-supplied nutrients, longest term storage)
-Organic matter (contains carbon, storage of N and anions)
-Adsborbed nutrients (ions attracted to soil colloids, readily available to plants)
-Dissolved ions (ions in solution, the most readily available to plants)
What is cation exchange capacity?
-Cation Exchange Capacity: Gives an insight into the nutrient retention capacity of soil and the total capacity of soil to hold exchangeable cations; CEC is an important index of nutrient status because available cations are the most important source of immediately available plant nutrients
What are some functions of urban soil?
-Regulation of water flow and quality
-Carbon storage
-Reservoir for biodiversity
-Platform for buildings
-Support for food and biomass production
What are two examples of soil contaminants and their characteristics?
-Lead (Pb): Neurotoxin affecting cognitive development and is immobile (lead-based paint, gasoline emissions)
-Arsenic (As): Human carcinogen that is very slowly leeching through soils (pesticides, pressure treated lumber)
BIODIVERSITY
What is speciation?
Speciation: Process by which evolution generates new species. Speciation rates depend on number of current species and the development of new species from existing species.
What is allopatric vs. sympatric speciation?
-Allopatric speciation: When the population becomes geographically isolated from the parent population (ex.) when a river cuts between two tree populations)
-Sympatric speciation: When two groups live in the same area but become different species (ex.) mutation)
What is Extinction?
Extinction: When species fail to reproduce and no individuals remain