Chapter 3 ES

Atmosphere

The whole mass of air surrounding the earth.

troposphere

innermost layer

Contains the air we breathe

Layer in which the earth’s weather occurs and

where life can survive.

Stratosphere

Layer above troposphere

The lower stratosphere, called the ozone layer,

contains enough ozone (O ) gas to filter out

about 95% of the sun’s harmful UV radiation.

hydrosphere

The hydrosphere contains all of the water on or near the earth’s surface.

Geosphere

The geosphere contains the earth’s rocks, minerals, and soil

and Earth’s Layers ( Core, Mantle, Crust)

Core

Inner core - hot, dense ball of iron

Outer core - hot, dense covering of iron and nickel

Mantle

Upper mantle - extends from

crust to deepest rock layers

Lower mantle - molten rock

Crust

Made up of rock and soil

Biosphere

The biosphere consists of the parts of the atmosphere, hydrosphere, and geosphere

where life is found

Made up of living (biotic) and

nonliving (abiotic) components.

Three Factors Sustain the Earth’s Life

One-way flow of high-quality energy, Cycling of nutrients, and gravity

One-way flow of high-quality energy

describes how energy enters ecosystems (primarily as sunlight), flows linearly through trophic levels via food chains, and is degraded into low-quality heat that cannot be reused

ex The sun’s energy supports plant growth and provides energy for

plants and animals.

Greenhouse effect

Natural effect that releases heat in the atmosphere near the earth’s surface.

Solar energy interacts with carbon dioxide (CO ), water vapor, and several other gases to warm the troposphere.

nutrient cycling through the biosphere

Nutrients are chemicals that organisms need to survive.

The earth does not get significant inputs of matter from space, its fixed supply of nutrients must be recycled to support life

Gravity

Allows the planet to hold on to its atmosphere and enables the movement and cycling of chemicals through air, water, soil, and organisms.

Ecology

The science that focuses on how organisms interact with one another and with their nonliving

physical environment of matter and energy

organism

any form of life

population

Group of individual organisms of the same species living in a particular area.

community

Populations of all species living and interacting in an area at a particular time.

ecosystem

One or more communities of different species interacting with one another and with the chemical and physical factors making up their nonliving environment.

trophic level

a position in a food chain, classifying organisms by what they eat

Producers

An organism that creates its own food, from sunlight forming the base of food webs by converting inorganic matter into organic energy that sustains all other life in an ecosystem

Photosynthesis

The process where plants use sunlight, water, and carbon dioxide to create their own food (sugars/glucose) and release oxygen as a byproduct, converting light energy into stored chemical energy for life

Consumers

organisms that cannot produce their own food

Primary (herbivores) Animals that eat mostly green plants

or algae

Secondary (carnivores) Animals that feed on other animals

Tertiary (omnivores) Higher-level consumers that feed on herbivores and other carnivores.

Decomposers

are consumers that get their nutrients by breaking down the wastes or remains of plants and

animals and release enzymes to chemically break down organic matter and absorb nutrients externally

Fungi, bacteria, and mold are the primary decomposers

Detritus feeders/ detritivores

Detritivores ingest or eat dead organic material (detritus) and digest it internally

Earthworms, woodlice, millipedes, sea cucumbers, and termites are detritivores.

Soil

Soil is a complex mixture of inorganic minerals (clay, silt, pebbles, and sand), decaying organic matter, water, air, and living organisms.

Natural capital that provides ecosystem service

Purifies water

Supplies most of the nutrients needed for plant growth.

Carbon sink (removes carbon from the atmosphere)

soil profile

Cross-sectional view of the horizons in a soil

microbes

tiny living organisms—including bacteria, viruses, fungi, archaea, protists, and algae

aerobic respiration

the metabolic process where cells use oxygen to break down food (like glucose) to generate large amounts of usable energy (ATP), producing carbon dioxide and water as byproducts

food chain

Series of organisms in which each eats or decomposes the preceding one.

food web

Complex network of many interconnected food chains and feeding relationships

pyramid of energy flow

the flow of energy through each trophic level in a food chain or food web. With each energy transfer, only a small part (typically 10%) of the usable energy entering one trophic level is transferred to the organisms at the next trophic level.

GPP (gross primary productivity)

The rate that an ecosystem’s producers convert energy into biomass

NPP (net primary productivity)

The rate that producers use photosynthesis to produce and store chemical energy minus the rate at which they use energy for aerobic respiration

Nutrient (biogeochemical) cycling

is driven by incoming solar radiation and earth’s gravity continually, moving nutrients and energy through air, water, soils, rocks, and living organisms

However, these chemical cycles are being altered by human

activities.

The Water Cycle

collects, purifies, and distributes the earth’s fixed supply of water

• Condensation in the atmosphere and effects of gravity create precipitation, which returns water to the earth’s surface

surface runoff

Water flowing off the land into bodies of surface water.
Surface runoff refills streams, rivers, lakes, wetlands, and the ocean

groundwater

Water that sinks into the soil and is stored in underground reservoirs called aquifers

aquifer

Porous, water-saturated layers of sand, gravel, or bedrock that can yield a significant amount of water

Humans impacter water cycle

By withdrawing fresh water resources faster than natural processes

replenish it

By replacing forests/vegetation with urban development—reducing

transpiration and increasing runoff

By draining and filling in wetlands, which disturbs the renewal

abilities of the hydrologic cycle

Carbon Cycle

the circulation of carbon in different chemical forms from the environment to organisms and then back to the environment.

How do Humans Alter The Carbon Cycle?

By extracting and burning fossil fuels at a much higher rate than

they are naturally formed

This adds carbon dioxide to the atmosphere and acidifies the ocean

By clearing forests faster than they regrow

This destroys carbon-absorbing vegetation

Nitrogen Cycle

Nitrogen (N) cycle: the cyclic movement of nitrogen in different chemical forms from the

environment to organisms and then back to the environment.

How do Humans Alter The Nitrogen Cycle?

By burning fossil fuels that adds nitric oxide (NO) to the atmosphere

Nitrogen dioxide gas (NO ) and nitric acid vapor (HNO ) causes acid

rain

By removing atmospheric nitrogen to make fertilizer

Agricultural runoff from fields into the water supply leads to algal

overgrowth that disrupts the oxygen balance in aquatic systems

Eutrophication

Phosphorus cycle

the cyclic movement of phosphorus (P) through water, the earth’s crust, and living organisms.

How do Humans Alter The Phosphorus Cycle?

By mining phosphorus deposits to make fertilizer

Through clearing of tropical forests, which reduces phosphorus

in the topsoil

Through agricultural runoff and topsoil erosion, which disturbs

biogeochemical cycling

How Do Scientists Study Ecosystems?

Scientists learn about ecosystems by:

Using field and laboratory research

Designing controlled experiments

Developing mathematical and statistical models