ISAT 320 Reading Quiz #2

natural system consisting of four components: mineral matter, organic matter water and air

soil

four components that make up soil

mineral matter
organic matter
water
air

soil inherits mineral matter from its

parent rock

soil inherits organic matter from its

living and decaying organisms

basic particles that result from weathering of rocks and contain inorganic salts found in soil

mineral matter

living or dead plant and animal materials in the soil

organic matter

soil particles have two major groups

coarse fraction
fine earth fraction

what determines the classification of a soil particle

size

particles greater than 2 mm in diameter

coarse fraction

particles equal to or less than 2 mm in diameter

fine earth fraction

size of coarse fraction

2 mm in diameter or greater

size of fine-earth fraction

equal to or less than 2 mm in diameter

fine-earth fraction groups

sand
silt
clay

sand particle size

2-.05 mm

silt particle size

0.05-0.002 mm

clay particle size

less than 0.002 mm

the relative proportions of sand, silt, and clay in a particular soil

soil texture

there are 12 of these and are used to classify soil

texture classes

used to determine the soil textural name after the percentages of sand, silt, and clay are determined from a laboratory analysis

textural triangle

soil consists of living organisms

biomass

large organisms in the soil (worms)

macroorganisms

small organisms in soil (fungi, bacteria)

microorganisms

is the space between particles of soil
it is filled with air and water

pore space

two types of pores in soils

macropores
micropores

these are larger than 0.08 in diameter
readily drain after heavy rain and then fill with air

macropores

size macropores has to be

larger than 0.08 in diameter

these are less than or equal to 0.08 mm in diameter
these drain slowly

micropores

the pores spaces are completely filled with water to the exclusion of air

saturation

the amount of water that soil can hold after being saturated with water and then allowed to drain for a period of 1-2 days

field capacity of soil

when plants have removed all the water they possibly can from the soil and begin to wilt

permant wilting point

soil scientist use the ___ scale to determine a soil's reaction

pH

an important property of soil solution is its ____

reaction (acid, neutral, or alkaline)

hydroxide ion outnumber hydrogen ions

alkaline (>7)

hydrogen ions outnumber hydroxide ions

acidic (<7)

the average weather conditions of an area
dominant factor in soil formation

climate

factors that are responsible for the kind of soil that develops in an area

soil forming factors

what are the 5 soil forming factors

climate
parent material
organisms
topography
time

measure of nutrients found in soil for plant growth

soil fertility

chemical element required for the normal growth of plants

essential element

essential nutrients required in large amounts by plants

macronutrients

other essential nutrients used in small quantities by plants

micronutrients

the breakdown of rock or other inorganic minerals that help to form soil

mineral weather

unconsolidated (soft and loose) material from which soils form. It may be mineral or organic

parent material

what does unconsolidated mean

soft and loose

three major parent material groups

residual
transported
organic

parent material

formed from the weathering of rock at a specific location

residual parent materials

parent material

transported from their place of origin and deposited in a new location

transported parent materials

Soils formed in areas where the rate of organic deposition exceeds the rate of residue decomposition

organic deposits

a symbiotic association between a fungus and one or more algae and/or cyanobacterial secrete very dilute carbonic acid that slowly dissolves rock, thus adding inorganic material to the developing soil

lichen

the shape or contour of the land surface, largely determines how water moves in a landscape and how susceptible soils are to water erosion

topography

layers in the soil

horizons

cross sectional view of the various horizons

soil profile

major layers from the ground surface downward to bedrock

master horizons

what are the master horizons

O
A
E
B
C
R

short definition of each horizon layer

O
A
E
B
C
R

organic later
top soil
subsurface
subsoil
parent material
bedrock

master horizons

__ - organic layer that forms above the mineral soil

O horizon

master horizons

___ - human survival depends on topsoil that covers much of the earth

A horizon

master horizons

___ - called the zone of leaching

much of the material in this layer is dissolved and carried downward to the B horizon by water

E horizon

master horizons

___ - Zone of accumulation that receives and stores clays, soluble salts, and humus that are leached downward from the A and E

B horizon

master horizons

__ - composed of unconsolidated parent material
material that is transported to a site by glaciers, wind, or water

C horizon

B horizon is known as

zone of accumulation

E horizon is known as

zone of leaching

master horizons

___ - bedrock with little evidence of weathering
determines many soil characteristics: texture, water-holding capacity, pH, nutrient levels

R horizon

this includes all soils of the world

soil classification (soil taxonomy)

12 major groups in the world

defined on the basis of having certain diagnostic horizons

soil orders

layers with distinct soil - forming processes

diagnostic horizons

soil orders

____ - form in hot, dry climates under desert vegetation like cactus, mesquite, and sagebrush

Aridisols

soil orders

___ - form in warm, wet climates under tropical rainforests

Oxisols

soil orders

young soils

Entisols

soil orders

weakly developed soils

Inceptisols

soil orders

____ - some of the world's most productive soils

mollisols

soil orders

____ - form in organic materials that build up in stagnent waters

histosols

soil orders

____ - found mainly on the sandy deposits
formed in a cool, relatively humid climate under forest vegetation

spodosols

___ ____ - horizon where iron, aluminum and humus have accumulated

spodic horizon

soil orders

__ and ____ - formed in humid climates and characterized by a subsoil argillic horizon

Alfisols and Ultisols

___ ___ - a thick, humus and nutrient rich surface horizon

mollic epipedon

___ ___ - silicate clays have accumulated from the layers above

argillic horizon

a layer of soil at the surface, or topsoil, that has specific characteristics to help classify soil

epipedon

soil orders

young soils with little profile development
presence of permafrost layer

Gelisols

soil orders

__ ___ - do not have thickness, dry, little organic matter

orchric epipedon

variant forms of a trait within a population of organisms

morphs

the movement of alleles from one population to another

gene flow

change in allele frequency in a population resulting from chance events

genetic drift

a random change in the base sequence of the genetic material

mutation

increase in the frequency of beneficial alleles within a population, resulting from individuals bearing those alleles having increased reproductive success

natural selection

changes in the characteristics of a population over time, more specifically, changes in allele frequencies within a population over time

evolution

variant form of a gene, or variant form of nucleotides at a particular DNA locus

allele

when a population has two or more forms of a particular trait

polymorphic

a gene that modifies the expression of a second gene

modifier gene

what are the two important concepts of evolutionary theory

1. Species change over time
2. Species are related to other species

change in frequency of alleles of a gene over time

genetic evolution

what 4 processes cause allele frequencies to change over time

gene flow
genetic drift
mutation
natural selection

what causes gene flow

emigration and immigration

migration of an individual out of their population

emigration

movement of an individual into a new population

immigration

proportion of variation in a trait that is due to genetic variation

heritability

a trait that increases an individuals reproductive success in a particular environment in comparison to individuals without that trait

adaptation

a large scale atmospheric system that affects global clime. An __ ___ is associated with high sea temp and low barometric pressure in the eastern Pacific ocean region

El Nino Southern Oscillation

El Nino

natural selection favors the evolution of one extreme phenotype, such that the mean phenotype shifts in one direction along a range of phenotypes

directional selection

evolutionary compromises between one function and another that prevents adaptations from being optimal in all environments

tradeoff