SCSC EXAM ACTUAL EXAM QUESTIONS AND CORRECT DETAILED ANSWERS WITH RATIONALES (VERIFIED ANSWERS) | ALREADY GRADED A

SCSC EXAM ACTUAL EXAM QUESTIONS AND CORRECT DETAILED ANSWERS WITH RATIONALES (VERIFIED ANSWERS) | ALREADY GRADED A+ Five soil forming factors active factors - ANSWER- -climate -biological activity Five soil forming factors passive factor - ANSWER- -parent material -time Five soil forming factors modifying factor - ANSWER- -topography (relief) relief - ANSWER- topography 6 key roles of soil - ANSWER- - medium for plant growth (nutrients, support, water, O2) - system for water supply and purification; regulates water flow - engineering medium (ex: roads) - habitat for soil organisms -modifier of atmosphere -recycling system for nutrients and organic waste what does a plant obtain from soil? - ANSWER- - water - physical support - air - temp. moderation - protection from toxins - nutrient elements 4 essential elements required for plant growth - ANSWER- Fe, Ca, Mg, K which soils are the best - ANSWER- Molisols which soils are the second best - ANSWER- alfisols which soils are the most weathered in the US - ANSWER- utisols which soils contain soluble salts - ANSWER- aridisols soils that can be eroded by wind - ANSWER- sand and organic not clay four principal components of soil (moist, mineral soil) - ANSWER- air-25% PORE SPACE water-25% PORE SPACE minerals-45-49% SOLIDS organic matter-1-5% SOLIDS -as water increases air decreases and vis versa lithosphere - ANSWER- starts at the surface of the earth and goes down biosphere - ANSWER- where most biological activity occurs atmosphere to lithosphere? soils with shallow surface horizon - ANSWER- clay soils oak v. conifer roots - ANSWER- shallow v. deep rooted what is the dominant source of surface water contamination - ANSWER- cities 2 aquifers in TX - ANSWER- -oogalala (largest) -Edwards (fractured limestone) most aquifers are dominated by - ANSWER- sand and gravel what is the Edwards aquifer dominated by - ANSWER- fractured limestone sand and gravel aquifers move (flux) ___ than limestone - ANSWER- slower how many microorganisms in 1g of soil - ANSWER- 10^6 to 10^8 cotton root rot can be avoided by - ANSWER- rotating crops climate includes - ANSWER- -precipitation -temp -wind what has the largest influence on soil - ANSWER- water parent material is ____ by active factors - ANSWER- unchanged soil profile - ANSWER- a vertical section of the soil through all its horizons and extending into the parent material -2D exposure of horizon A horizon - ANSWER- topsoil almost always on top (sometimes O on top) -more porous -less clay (more sand and silt) -smaller aggregates -darker more OM -more plant roots B horizon - ANSWER- subsoil -more compact (dense) -more clay -larger aggregates -less OM C horizon - ANSWER- parent material that can be dug when moist -middle clay content -uncolidated -under solum -like parent material R horizon - ANSWER- parent material that cant be dug when moist -weathered to give soil the least weathered soil does not have which horizon - ANSWER- B A&B horizons= - ANSWER- solum -acted upon by soil forming factors pedon - ANSWER- 3D -smallest 3D soil unit with all the characters of the soil -the discrete soil individual -size varies -smallest is 1 m^2 at soil surface and extends downward to a max depth of 2m -smallest soil individual that contains all the characters of the soil solum - ANSWER- A&B horizons regolith - ANSWER- A&B&C horizons can be dug when moist -all soil above bedrock bedrock - ANSWER- R horizon -solid (cant be dug) smallest solids are - ANSWER- colloids (clay sized particles) where do most reactions occur - ANSWER- surface area clay has a large - ANSWER- surface area/ mass or volume -very reactive? igneous - ANSWER- formed from the cooling of magma Acidic igneous rock intrusive and extrusive - ANSWER- siliceous -coarse (intrusive): granite -fine(extrusive): rhyolite Basic igneous rock intrusive and extrusive - ANSWER- mafic -coarse (intrusive): gabbro -fine(extrusive): basalt minerals commonly in siliceous igneous - ANSWER- (acidic) -quartz -K-feldsbar -a dark mineral such as mica, amphibole, pyroxene mafic igneous - ANSWER- (basic) -olivine -pyronene -amphibole -mica -Na, Ca-feldsbars sedimentary - ANSWER- formed from the deposition of sediments or evaporation of water, and consolidation sedimentary ex: and what there made of - ANSWER- -limestone: calcite (marine), sometimes dolomite -sandstone: quartz - shale: silicate clay minerals metamorphic - ANSWER- formed from pre-existing rocks through pressure and/or high temperatures. metamorphic ex: - ANSWER- -marble which comes from limestone -quartzite which comes from sandstone -slate which comes from shale -gneiss which comes from granite (layered) *all metamorphic rocks are more dense then there precurser most common rock type - ANSWER- sedimentary -covers approx. 75% of the Earths land surface shale and limestone are - ANSWER- sedimentary granite and basalt are - ANSWER- igneous physical weathering - ANSWER- temp water ice wind plants animals small size = ___ surface area - ANSWER- large name the major components of a typical, moist surface soil and give the percentage of each component by volume - ANSWER- Pore space- Air-25%, Water 25% = 50% Solids- Minerals 45-49%, Organic Matter 1-5% = 50% name three primary minerals that weather to form secondary clay minerals in soils - ANSWER- -feldspars such as orthoclase -Amphiboles -pyroxenes -micas-biotite ,muscovi