Science Exam 2

System

is a network of relationships among parts that influence each other through the exchange of energy

Lithosphere

the rock and sediment in the upper mantle and crust.

atmosphere

the air surrounding the planet

hydrosphere

includes all surface, underground, and atmospheric water

Biosphere

consists of all the planet's organisms and the abiotic portions they interact with.

biotic factors

Anything that is or was living

emergent properties

• characteristics that are not evident from their components alone

• characteristics that are not evident in the system's individual components but are evident only by looking at the whole operating system

For example: Studying the cell and tissue organization of a tree would not predict its importance as a habitat or food source.

feedback loop

a circular process in which a system's output serves as input to that same system

negative feedback loop

results when a system moving in one direction acts as an input that causes the system to move in the opposite direction.

• Negative feedback enhances stability in a system.

positive feedback loop

occur when increased output in a system leads to increased input, which further stimulates output.
- are more common in natural systems altered by human actions
- This can be incredibly destabilizing for a system
- The accelerating melting of glaciers and sea ice in the Arctic is an example.

dynamic equilibrium

Negative feedback systems with processes that move in opposing directions at equivalent rates

Homeostasis

the tendency of a system to maintain stable internal conditions.

Runoff

water that flows over the ground surface rather than soaking into the ground

airshed

the geographic area that produces air pollutants that are likely to end up in a waterway

The Chesapeake Bay system includes both the watershed and the airshed

The EPA was sued by the Chesapeake Bay Foundation in 2009 for failing to protect the bay

What happened to the Chesapeake Bay?

The bay has also been polluted with excessive nitrogen and phosphorus nutrients from fertilizers, animal manure, and fossil fuel combustion in the watershed.

-These nutrients, combined with the loss of the oysters, led to an overpopulation of phytoplankton.
- Decomposition of dead plankton has depleted the water, creating hypoxia.

The majority of the nitrogen and phosphorus nutrient pollution in the bay comes from agriculture.

Eutrophication

occurs as bacteria deplete oxygen, suffocating other organisms

• a contributing factor is nitrogen and phosphate pollution

Ecosystem

consists of all organisms and nonliving entities that occur and interact in a particular area at the same time.

Ecological communities include only living organisms.

The Chesapeake Bay estuary

is an ecosystem where rivers flow into the ocean, mixing salt and fresh water

primary production

The conversion of solar energy into chemical bonds in sugars

-The more rapidly photosynthesis makes more biomass, the higher the primary productivity

gross primary production

total chemical energy produced by autotrophs

net primary production

-The energy that remains after respiration is used to generate biomass (leaves, stems, and roots)

-Can be calculated by subtracting respiration from gross primary production

-Freshwater wetlands, tropical forests, coral reefs, and algal beds each have a high net primary productivity.

-tends to increase with temperature and precipitation on land / Increases with nutrients and sunlight in water

secondary production

Energy used by consumers to generate their own biomass

productivity

The rate at which producers convert solar energy to biomass

Nutrients

are elements and compounds that organisms require for survival.

Macronutrients

Elements and compounds (nitrogen, carbon, phosphorus) needed in large amounts

Micronutrients

Nutrients needed in smaller amounts (zinc, copper, iron)

dead zones (in oceans)

hypoxic (low-oxygen) areas in the world's oceans and large lakes

Ecotones

a boundary between two types of ecological communities

Areas where ecosystems meet in a transitional zone

landscape ecology

focuses on the factors controlling exchanges of energy, materials, and organisms across multiple ecosystems

Due to the intermixing of ecosystems, ecologists may view systems on a larger geographic scale that includes multiple ecosystems.

patches

An area of habitat that differs from its surroundings and has sufficient resources to allow a population to persist

A landscape is made of a spatial array of patches, which may be specific ecosystems or areas of habitat of an organism.

mosaic

Patches are spread out spatially over a landscapein a mosaic.

metapopulation

Travelling between patches is dangerous and energy-intensive for organisms.

• If the patches are far enough apart, a population may be divided into subpopulations.
  - A network of subpopulations, with limited movement between them, is called a metapopulation.
  - a network of separate populations with some interbreeding between them

If patches are highly isolated

individuals may not be able to move between them at all. This creates an extinction risk within subpopulations.

Conservation biologists

study the loss, protection, and restoration of biodiversity

geographic information system (GIS).

A common research tool that takes multiple types of data (geology, topography, vegetation, etc.) and combines them into layers on a set of geographic coordinates.

model

-is a simplified representation of a complex natural process. -

-The biosphere contains many complex systems, which are often studied as models
- Models make predictions, which are tested against new data. This leads to refinements.

Ecological modeling

• involves constructing and testing models to explain and predict ecological systems.

• based on hypotheses formed from data and observations.

Human society depends on the services provided by ecological processes including the following:

- Soil formation
- Water purification
- Pollination
- Breakdown of biodegradable waste
- Stability of negative feedback cycles
The most important may be the cycling of the elements we call macronutrients and micronutrients.

Which of these ecosystems would you expect to have thegreatest net primary productivity? a. A savanna b. A tundra c. Cultivated farmland d. An estuary

An estuary

What is the first step in developing an ecological model?

Forming hypotheses

nutrient cycles

Also known as biogeochemical cycles, the comprehensive set of cyclical pathways by which a given nutrient moves through the environment. In these pathways, chemical elements or molecules travel the atmosphere, hydrosphere, and lithosphere, and from one organism to another, in dynamic equilibrium

(In the biogeochemical cycles) Nutrients move from one reservoir, or pool, to another for varying amounts of time, called the____.

residence time

(In the biogeochemical cycles) When a reservoir releases more materials than it accepts it is called a

source

• short residence time

When a reservoir accepts more materials than it releases it is called a

sink

• long residence time

Flux

is the rate at which materials move between reservoirs.

Water is the medium for all biochemical reactions

and it plays key roles in nearly every environmental system.

hydrologic cycle

summarizes how water flows as a solid, liquid, and gas through our environment.
- The oceans are the main reservoir (97%) for water.
- Only about 3% is fresh water, and two-thirds of that is frozen in glaciers, ice caps, and snowfields.

Transpiration

is the release of water vapor by plants through their leaves.

• is a process that helps pull water from the roots, up the stems, and through the leaf.

• Dissolved substances are left behind.

  
  

Evaporation

converts water from a liquid to gaseous form, taking it to the atmosphere.
- Both warmer temperatures and strong winds increase the rate of evaporation of water.

Precipitation

Water returns to Earth's surface as precipitation when it condenses into rain or snow.

• Most of it flows as runoff into surface waters.

groundwater

Some precipitation and surface water soaks down through soil and rock, becoming groundwater.
- Groundwater recharges underground aquifers.

water table

the upper limit of groundwater in an aquifer

Human activity impacts every aspect of the water cycle.

• Damming rivers slows the movement of water and increases evaporation from reservoirs.

• Removing vegetation increases runoff and decreases infiltration and transpiration.

• Withdrawal of groundwater lowers water tables.

• Air pollution can change the chemical nature of precipitation.

Carbon

is found in all organic molecules—carbohydrates, fats, and proteins, which make up living organisms.

carbon cycle

The organic circulation of carbon from the atmosphere into organisms and back again

nitrogen

Nitrogen is an essential ingredient in DNA, RNA, and proteins.
- Nitrogen gas (N2) makes up 78% of the atmosphere, but is chemically inert and cannot leave the atmosphere without assistance.

nitrogen cycle

Under the right conditions, nitrogen can become biologically active and enter the biosphere and lithosphere

nitrogen fixation

inert nitrogen gas becomes biologically available by combining with hydrogen to form ammonia, whose water-soluble ions of ammonium can be taken up by plants.
- The intense energy of lightning strikes can also fix nitrogen.

Nitrogen-fixing bacteria

convert nitrogen gas into ammonia.

▪The bacteria form nodules on plant roots, absorbing sugars from the roots in exchange for nitrogen fixation.
▪Found in legumes, such as soybeans

Nitrification

converts ammonium ions into nitrite ions, then into nitrate ions which plants can directly take up.
- These ions are also added to the soil through the use of fertilizer.

Denitrifying bacteria

convert nitrates back into nitrogen gas.

bottleneck

• a step that limited the flux of nitrogen out of the atmosphere.

• Nitrogen fixation has historically been a bottleneck

Haber-Bosch process

enabled people to artificially fix nitrogen, greatly enhancing agriculture.
- Humans have effectively doubled the rate of nitrogen fixation on Earth.

Runoff can cause excess nitrogen to enter waterways

causing eutrophication.

Burning fossil fuels releases additional nitrogen into the atmosphere.

What is the largest reservoir of carbon?

sediments

The Haber-Bosch process has reduced a bottleneck and greatly enhanced the availability of what nutrient?

Nitrogen

Energy

is the capacity to change the position, composition, or temperature of matter.

When energy causes an object to move it is a force that can accomplish ______.

work

potential energy

is the energy of position or composition.

• Stored energy held in readiness

• For example

  , river water held behind a dam contains potential energy.

Kinetic energy

is the energy of motion.

• Ex. River water rushing through a dam and downstream contains kinetic energy.

Is Energy able to be converted back and forth between the two forms (Kinetic and Potential)?

Yes

Converting molecules with high-energy bonds (such as glucose) to molecules with low-energy bonds(such as carbon dioxide) releases what kind of energy?

kinetic energy

first law of thermodynamics

Energy can change from one form to another, but it cannot be created or destroyed.

second law of thermodynamics

Energy tends to change from a more-ordered to a less-ordered state as it changes form.

Example of the laws of thermodynamics

a log of firewood is a highly organized and structurally complex product that contains a lot of useful potential energy

When the firewood is burned, carbon dioxide, water, and kinetic energy is released. (First Law)

The leftover ash has much less structure and useful potential energy. (Second Law)

energy conversion efficiency

the ratio of the useful output of energy to the amount input.

Some forms of energy, like fossil fuels, are concentrated and relatively easy to harness. Others, like sunlight, are much more diffuse and difficult to collect. energy conversion efficiency measures this.

autotrophs

Organisms that are able to make their own food

The Calvin cycle reactions link together _____ to form ______?

carbon atoms, sugars

Plants take in ____ through their roots, absorb _____ from the air through their leaves, and harness the power of _____ to generate ____ and _____.

water, carbon dioxide, sunlight, sugar, oxygen

heterotrophs

An organism that obtains organic food molecules by eating other organisms or their by-products.

cellular respiration

the process by which cells use oxygen to produce energy from food

cellular respiration is the exact opposite of _____

photosynthesis

Magma

Radioisotopes decay and release heat, which gradually moves toward the surface and melts rock into magma.
-Magma can erupt from volcanoes, power plate tectonics, and heat groundwater.

hydrothermal vents

spots on the ocean floor where hot gases and minerals escape from earth's interior into the water

chemosynthesis

Organisms living near hydrothermal vents can use the chemical potential energy in hydrogen sulfide (H2S) to produce sugar.

6 CO2 + 6 H2O + 3 H2S → C6H12O6 + 3 H2SO4

An inventor claims to have the ability to transform potential energy to kinetic energy without any decrease in the energy's quality. What law does this violate?

The second law of thermodynamics

According to the photosynthesis reaction, autotrophs use _______ as a source of energy, and_______ as a source of mass.

sunlight; carbon dioxide and water

carbon dioxide and water

What name is given to the process by which detritivores return carbon to the atmosphere?

Decomposition

Detritus is composed of _____.

Dead organic matter and excreted wastes.

What removes carbon from the atmosphere?

Photosynthetic organisms

Nitrifying bacteria convert _____ to _____.

ammonium ... nitrites

_____ removes nitrogen from the atmosphere.

nitrogen fixation

Which of the following best characterizes the factors that have contributed to the dead zone in the waters of the Chesapeake Bay for the past few decades?

A. gasoline spillage from the refineries
B. fertilizer runoff from farms, animal manure, and stormwater runoff in the watersheds surrounding the Chesapeake Bay
C. the farm practices around the Chesapeake Bay
D. increasing oil spills in the Chesapeake Bay

fertilizer runoff from farms, animal manure, and stormwater runoff in the watersheds surrounding the Chesapeake Bay

Most energy in the majority of ecosystems arrives as ______ and exits in the form of _____.

radiation from the sun, heat