Chapter 1: The Living World: Ecosystems (copy)

Ecosystem

A community of living (biotic) organisms interacting with the non-living (abiotic) components of their environment as a system through various nutrients and energy cycles.

Organism

A living thing that can function on its own.

Species

Organisms that resemble each other; are similar in genetic makeup, chemistry, and behavior; and are able to interbreed and produce fertile offspring.

Population

Organisms of the same species that interact with each other and occupy a specific area.

Community

Population of different species.

Ecological Niche

A particular area within a habitat occupied by an organism, as well as the function of that organism within its ecological community.

Physical environment

It influences how organisms affect and is affected by resources and competitors.

Niche

It reflects the specific adaptations that a species has acquired through evolution.

Generalists

Able to survive on a wide variety of food resources, environmental conditions, and lives in broad niches

Specialists

Specific/limited number of prey; prone to extinction, sensitive to environmental change; live in narrow niches

Symbiosis

A term used to describe any type of close and long-term biological interaction between two different biological organisms of the same or different species.

Amensalism

The interaction between two species whereby one species suffers and the other species is not affected.

Commensalism

The interaction between two species whereby one organism benefits and the other species is not affected.

Competition

It can be either intraspecific and interspecific. It is the driving force of evolution whether it is for food, mating partners, or territory.

Intraspecific

Competition between members of the same species.

Interspecific

Competition between members of different species.

predator–prey relationships

Competition is prominent in ________, with the predator seeking food and the prey seeking survival.

Mutualism

The interaction between two species whereby both species benefit.

Parasitism

The interaction between two species whereby one species is benefited, and the other species is harmed.

Saprottrophism

Saprotrophs obtain their nutrients from dead or decaying plants or animals through the absorption of soluble organic compounds.

Law of Tolerance

It states that the existence, abundance, and distribution of species depend on the tolerance level of each species to both physical and chemical factors.

Limiting Factor

Any abiotic factor that limits or prevents the growth of a population.

**Predator-prey cycles**

**These** are based on a feeding relationship between two species:

* If the prey species rapidly multiply, the number of predators increases until the predators eventually eat so many of the prey that the prey population dwindles again.

Spatial partitioning

It occurs when competing species use the same resource by occupying different areas or habitats within the range of occurrence of the resource

Biomes

These are major regional or global biotic communities characterized by dominant forms of plant life and the prevailing climates

*average air temperature*

*amount of rainfall*

The geographical distribution of the various terrestrial biomes is controlled primarily by the *______* and the *_______* the biome receives.

Deserts

They cover about 20% of Earth’s surface and occur where rainfall is less than 20 inches (50 cm) per year.

Arctic tundra

It is a cold desert due to the low amount of rainfall it receives yearly.

Forests

It cover about one-third of Earth's land surface, mostly in North America, the Russian Federation, and South America, and account for 75% of gross primary productivity and plant biomass.

Ecozones

_____ like boreal forests near the poles and tropical forests near the equator are formed by forests at different latitudes and elevations.

Tropical Rainforests

• The length of daylight is 12 hours and varies a little year-round

• Large diversity of species.

• Occur near the equator.

• Annual rainfall exceeds 80 inches (200 cm) and is evenly distributed.

• Plants are highly diverse.

• Tree canopy is multilayered and continuous, allowing little light penetration.

Temperate Deciduous Forests

• Occur in eastern North America, northeastern Asia, and western and central Europe.

• Have a distinct winter, moderate climate, and a 140–200-day growing season during four to six frost-free months.

• Temperature varies from –20°F to 85°F (–30°C to 30°C).

• Precipitation averages 30–60 inches (75–150 cm) per year.

• Fertile soil is enriched by decaying leaf litter.

Temperate Coniferous Forest

• Found in temperate regions with warm summers, cool winters, and enough rainfall to support forests.

• Common in coastal areas with mild winters and heavy rainfall, or inland in drier climates or mountains.

Taiga

Largest terrestrial biome; found in northern Eurasia, North America, Scandinavia, and two-thirds of Siberia.

Savannas

These are grasslands with scattered individual trees and cover almost half the surface of Africa and large areas of Australia, South America, and India.

Temperate Grasslands

Here grasses are the dominant vegetation, while trees and large shrubs are absent.

Tundra

It has extremely low temperatures, large repetitive population changes, limited soil nutrients, little precipitation, low biotic diversity, poor drainage, short growing and reproductive seasons, and simple vegetation structure.

Permafrost

A layer of permanently frozen subsoil.

75%

Oceans cover approximately ____ of Earth’s surface and have a salt concentration of about 3%.

Evaporation

______ of seawater is the primary source of most of the world’s rainfall.

Convection

The circular motion that occurs when warmer air or liquid rises, while the cooler air or liquid sinks.

Littoral Zone

Also known as the *intertidal zone*, it is the part of the ocean that is closest to the shore.

Neretic Zone

Also known as the *sublittoral zone*, this zone extends to the edge of the continental shelf.

Photic Zone

The uppermost layer of water in a lake or ocean that is exposed to sunlight down to the depth where 1% of surface sunlight is available.

Artificial lakes

These are constructed for hydroelectric power generation, recreational purposes, industrial and agricultural use, and/or domestic water supply.

Benthic Zone

The bottom of lake, organisms can tolerate cool temperatures and low oxygen levels.

Limnetic Zone

A well-lit, open surface water, farther from shore, extends to a depth penetrated by light, occupied by phytoplankton, zooplankton, and higher animals; produces food and oxygen that supports most of a lake’s consumers

Profundal Zone

It is deep, no-light regions, too dark for photosynthesis; low oxygen levels; inhabited by fish adapted to cool, dark waters

Oligotrophic (Young Lake)

Deep, cold, small surface area relative to depth; nutrient-poor, phytoplankton are sparse; not very productive; doesn’t contain much life; waters often very clear; and sediments are low in decomposable organic matter.

Mesotrophic (Middle-Aged Lake)

Moderate nutrient content and moderate amounts of phytoplankton; reasonably productive.

Eutrophic (Old Lake)

Shallow, warm, large surface area relative to depth; Waters often murky;

stratification

The ______ or layering of water in lakes is the result of density changes caused by shifts in temperature.

hypolimnion

Deep water is insulated from the sun and stays cool and denser, forming a lower layer called the _______.

Seasonal turnover

_______ refers to the exchange of surface and bottom water in a lake or pond that happens twice a year.

Fall Turnover

• With the arrival of fall and cooler air temperatures, water at the surface of a lake begins to cool and becomes heavier.

• During this time, strong fall winds move the surface water around, which promotes mixing with deeper water.

Spring Turnover

• With spring, the surface ice begins to melt, and cold surface waters warm until they reach the temperature of the bottom waters, again producing a fairly uniform temperature distribution throughout the lake.

• When this occurs, winds blowing over the lake again set up a full circulation system.

Wetlands

These are areas that are covered with water at some point in the year and that support aquatic plants.

Source Zone

• Contains headwaters or headwater streams and often begins as springs or snowmelt of cold, clear water with little sediment and relatively few nutrients.

• Narrow rocky channels, creating swift currents.

Transition Zone

• Contains slower, warmer, wider, and lower-elevation moving streams, which eventually join to form tributaries.

• The water is less clear as it contains more sediment and nutrients, with the substrate beginning to accumulate silt.

Floodplain Zone

• As a result of large amounts of sediment and nutrients, the water is murky and warmer.

• Tributaries join to form rivers, which empty into oceans at estuaries.

Riparian areas

These are lands adjacent to creeks, lakes, rivers, and streams that support vegetation dependent upon free water in the soil.

Carbon

It is exchanged among the biosphere, geosphere, hydrosphere, and atmosphere and is the basic building block of life and the fundamental element found in carbohydrates, fats, proteins, and nucleic acids.

ocean acidification

The creation of coral reefs and the viability of externally fertilized egg cells are disrupted by __________ caused by carbon dioxide absorption.

Plant Matter

A portion of atmospheric carbon (\~15%) is removed through photosynthesis.

Terrestrial Biosphere

Forests store about 90% of the planet’s above-ground carbon and about 75% of the planet’s soil carbon.

Oceans

The carbon in carbon dioxide dissolved in seawater is utilized by phytoplankton and kelp for photosynthesis.

Sedimentary Deposits

Limestone (CaCO3) is the largest reservoir of carbon in the carbon cycle.

Nitrogen

It is an essential element needed to make amino acids, proteins, and nucleic acids; It makes up 78% of the atmosphere.

nitrogen cycle

Fossil fuel combustion, inorganic fertilizer use, and wastewater and sewage production have drastically altered the _________.

Nitrogen

• It increases water acidification, eutrophication, and toxicity.

• It is needed for photosynthesis and plant growth in chlorophyll.

• It availability affects primary production and decomposition.

Nitrogen Fixation

Atmospheric nitrogen is converted into ammonia (NH3) or nitrate ions (NO3–), which are biologically usable forms of nitrogen.

natural cycling of nitrogen

The __________, in which atmospheric nitrogen is converted to nitrogen oxides by lightning and deposited in the soil by rain, where it is assimilated by plants and either eaten by animals or decomposed back to elemental nitrogen by bacteria, includes the following processes:

Rhizobium

The key participants in nitrogen fixation are legumes, such as alfalfa, clover, and soybeans, and nitrogen-fixing bacteria known as ________.

Nitrification

Ammonia (NH3) is converted to nitrite (NO2–) and nitrate (NO3–), which are the most useful forms of nitrogen to plants.

Assimilation

Plants absorb ammonia (NH3), ammonium ions (NH4+), and nitrate ions (NO3–) through their roots.

Ammonification

Decomposing bacteria convert dead organisms and wastes, which include nitrates, uric acid, proteins, and nucleic acids, to ammonia (NH3) and ammonium ions (NH4+)—biologically useful forms.

Denitrification

Anaerobic bacteria convert ammonia into nitrites (NO2–), nitrates (NO3–), nitrogen gas (N2), and nitrous oxide (N2O) to continue the cycle.

nitrogen oxides (NOx)

Fossil fuel combustion has sevenfold increased atmospheric _________, particularly nitrogen dioxide.

NOx

____ produces tropospheric ozone, smog, acid rain, and nitrogen inputs to ecosystems.

Ammonia (NH3)

_______ in the atmosphere has tripled as a result of human activities since the Industrial Revolution.

Nitrous oxide (N2O)

This greenhouse gas breaks down and destroys atmospheric ozone in the stratosphere.

**Phosphorus**

* **It** is not found in the atmosphere; rather, the primary sink for phosphorus is in sedimentary rocks.
* It is found in the form of the phosphate ion or the hydrogen phosphate ion.
* It is slowly released from terrestrial rocks by weathering and the action of acid rain and then dissolves into the soil and is taken up by plants.
* It is often a limiting factor for soils due to its low concentration and solubility, and it is a key element in fertilizer.

Water cycle

It is powered by energy from the sun, which evaporates water from oceans, lakes, rivers, streams, soil, and vegetation.

dynamic equilibrium

The water cycle is in a state of __________ by which the rate of evaporation equals the rate of precipitation.

Condensation

The conversion of a vapor or gas to a liquid

Evapotranspiration

The process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants

Infiltration

The process by which water on the ground surface enters the soil

Precipitation

Rain, snow, sleet, or hail that falls to the ground

Runoff

Part of the water cycle that flows over land as surface water instead of being absorbed into groundwater or evaporating

Floating ice

Essential to life near the poles, results from the different ways water molecules arrange themselves at different temperatures.

Aquifer

A geologic formation that contains water in quantities sufficient to support a well or spring.

Land subsidence

The sinking of land that results from groundwater extraction.

Water shortages

Since groundwater is the main water source for many populations, residents of these areas may experience water insecurity for domestic and agricultural needs.

Saltwater intrusion

The movement of saltwater into freshwater aquifers, which can lead to contamination.

Photosynthesis

The plants remove carbon dioxide from the atmosphere and use light energy to produce carbohydrates and other organic compounds

chlorophyll

Plants capture light primarily through the green pigment _________.

Oxygen gas

It is released into the atmosphere during photosynthesis, and plants emit carbon dioxide during respiration.

Trophic Level

Food web: The natural interconnection of food chains.The position an organism occupies in a food chain and is the number of steps it is from the start of the chain.

Ecological pyramids

These show ecosystem properties by placing primary producers at the base and decreasing energy as species move away from them.

Primary consumers

They have longer life spans and slower growth rates and accumulate more biomass than the producers they consume.