AP Environmental Science Midterm Exam Review

UNIT 1: LIVING WORLD

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Tundra

A cold and treeless biome with low-growing vegetation

Boreal Forest/Taiga

A forest biome made up primarily of coniferous evergreen trees that can tolerate cold winters and short growing seasons

Temperate rainforest

A coastal biome typified by moderate temperatures and high precipitation

Temperate seasonal forest

A biome with warm summers and cold winters with over 1m (39 inches) of precipitation annually

Woodland/shrubland

A biome characterized by hot, dry summers and mild, rainy winters

Temperate grassland/cold desert

A biome characterized by cold, harsh winters, and hot, dry summers

Tropical rainforest

A warm and wet biome found between 20N and 20S of the equator, with little seasonal temperature variation and high precipitation

Tropical seasonal forest/savanna

A biome marked by warm temperatures and distinct wet and dry seasons

Subtropical desert

A biome prevailing at approximately 30N and 30S with hot temperatures, extremely dry conditions, and sparse vegetation

Major biogeochemical cycles

Nitrogen, carbon, water, phosphorus, and sulfur

Water cycle

Reservoirs are the atmosphere and hydrosphere; Processes include Evaporation, Condensation, Precipitation, Transpiration; After precipitation water can take various paths including Surface runoff, Glaciers, Seepage, Aquifers/groundwater, Absorption by plants.

Carbon cycle

Reservoirs are the geosphere; Processes include photosynthesis, cellular respiration, deposition, lithification (converting loose C-containing sediment into rock)

Nitrogen cycle

Reservoirs are the atmosphere; Processes include Nitrogen fixation, Nitrification, Assimilation, Decomposition, Denitrification

Phosphorous cycle

Reservoirs are the geosphere; Process is slow in which water runs over rocks and erodes away compounds containing Po4^3- and it can be lost from cycle for long periods when it washes from the land into the ocean.

Sulfur cycle

Reservoirs are underground in rocks, minerals, and fossil fuels

A simple nitrogen cycle

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Nitrogen fixation

Nitrogen gas is converted to ammonia through bacteria absorption and lightning because plants and animals cannot absorb nitrogen.

Nitrification

Converts NH4 into NO2 then into NO3 for plants.

Assimilation

Converts the nitrogen into proteins or DNA

Decomposition

(Ammonification) As the bodies and wastes decompose, bacteria convert the nitrogen compounds into NH4

Denitrification

Bacteria converts NH4 into N2

What are ways carbon dioxide is taken out of the atmosphere and put back into the atmosphere?

Through deforestation, burning of fossil fuels and wood, and cellular respiration

Reactants and Products for photosynthesis

Carbon dioxide and Water → Sugar (glucose) and Oxygen

Reactants and Products for cellular respiration

Sugar (glucose) and Oxygen → Carbon dioxide and Water and ATP

Abiotic

Not derived from living organisms (Includes water, air, temperature, soil, light levels, precipitation, salinity)

Biotic

Derived from living organisms (Include producers, consumers, decomposers, plants, animals, bacteria/fungi)

Parasitism

One species benefits while one is harmed

Mutualism

Both species benefit

Commensalism

Where one species benefits while the other is unaffected

Competition

Neither benefits

Predation

One species benefits while the other dies

Order Levels for Ecosystems

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Individual/Organism

The lowest level of organization in an ecosystem

Population

Multiple individuals or organisms of a single species that live within a particular geographic area

Community

Two or more populations of different species that occupy the same space at the same time

Ecosystem

Both the biotic (living) and abiotic (nonliving) factors in a system

Biome

The plants and animals in a biome share common traits that are specific to the individual biome those plants and animals inhabit

10% rule for energy transfer in food chains

Each trophic level can only give 10% of its energy to the next level

Energy and biomass pyramid

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GPP

Gross primary productivity is the rate at which an ecosystem's producer converts solar energy into chemical energy in the form of biomass found in their tissues; Units are kcal/m^2/yr

NPP

Amount of energy potentially available to other organisms in the ecosystem

R

The energy used in respiration

Formula for NPP

NPP = GPP - R

Producers

Organisms that can make their own food through photosynthesis or chemosynthesis

Primary consumers

Organisms that eat producers

Secondary consumers

Organisms that eat primary consumers

Tertiary consumers

Organisms that eat secondary consumers

Scavengers

Organisms that feed

Detritivores

Animals that feed on dead organic material

Decomposers

Organisms that bread down dead or decaying organisms

Heterotrophs and Autotrophs

Heterotrophs are organisms that have to to consume food while autotrophs are organisms that make their own food.

Understand the effects of eliminating a species in a food chain. 

Example: What would happen to the other species (increase or decrease?) if the desert fox was overhunted and eliminated?

Cacti à kangaroo rats à snakes à desert fox

UNIT 2: BIODIVERSITY

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Biodiversity

the variety of different species

Genetic diversity

the variety of genes within a given species

Evolution

a change in the genetic composition of a population over time

Adaptations

a trait that improves an individual’s fitness

Artificial Selection

the process in which humans determine which individuals breed, typically with a preconceived set of traits in mind

Natural Selection

the process in which the environment determines which individuals survive and reproduce

Fitness

an individual’s ability to survive and reproduce

Mutation

a mutation can arise in a population and if it is not lost it may increase in frequency over time

Gene Flow

the process by which individuals move from one population to another and thereby alter the genetic composition of both populations. It can bring about genetic variation.

Genetic Drift

a change in the genetic composition of a population over time as a result of random mating

Bottleneck effect:

a reduction in the genetic diversity of a population caused by a reduction in its size. It can reduce genetic variation. It can create low diversity and could lead to decline or extinction.

Founders effect

A change in the genetic composition of a population as a result of descending from a small number of colonizing individuals

Range of ecological tolerance

the limits to the abiotic conditions that a species can tolerate such as humidity, temperature, salinity, and pH

Limiting factors

restricts growth, abundance, or distribution of a population

Realized Niche

the range of abiotic and biotic conditions under which a species actually lives

Fundamental Niche

The suite of abiotic conditions under which a species can survive, grow, and reproduce

Niche Generalists

A species that can live under a wide range of abiotic or biotic conditions. Fare better under changing conditions because they have a number of alternative habitats and food sources available.

Ex. Cockroaches

Niche Specialists

a species that is specialized to live in a specific habitat or to feed on a small group of species. Do well when environmental conditions remain relatively constant; however, loss of a favored habitat or food source leaves them with few alternatives for survival

Ex. Tiger Salamanders- must live in fishless ponds

Resource Partitioning

division of resources in an ecosystem

Ecosystem services

Goods that come from natural resources or services that ecosystems carry out that have measurable economic value to humans.

Provisioning

goods taken directly from ecosystems or made from natural resources (wood, paper, food)

Regulating

natural ecosystems regulate climate/air quality, reducing storm damage and healthcare costs

Cultural

money generated by recreation (parks, camping, tours) or scientific knowledge

Supporting

Natural ecosystems support processes we do ourselves, making them cheaper and easier (bees pollinate crops)

HIPPCO

Habitat Fragmentation/Loss, Invasive Species, Population growth, Pollution (Pollutants), Climate Change, Over Exploitation

Habitat Fragmentation/loss

Breaking of larger, continuous habitats into smaller, isolated patches; disrupts breeding, hunting migration.

Deforestation (lumber, cities, roads) Wetland draining (ag, urbanization) River water level decreased by dams.

Invasive Species

Invasives such as z. mussel and kudzu vine outcompete native species for food/space, lowering population

Population Growth

Human pop. growth drives habitat loss

Urbanization, ag. expansion to feed more people so remove/fragment habitats.

Pollution (Pollutants)

Oil spills reduce marine original population sizes

Pesticides (glyphosate, atrazine) kill non-target species

Climate Change

Shifts biomes and therefore species habitats ranges, can change temp. and precip. patterns too rapidly for a species to adapt or migrate, causing pop. decline or extinction

Over Exploitation

Excessive hunting or poaching (faster than reproductive rate) leads to pop. decline & potential extinction

Trophic cascade

ecological event triggered by adding or removing apex predators

Tropic level

Organisms that are same number of energy transfers from source

Food Web

A community of organisms where there are several interrelated food chains

Keystone species

species have a large effect on the types and abundances of other species in an ecosystem. They are low in number and are usually prone to extinction.

Loss of keystone species usually lead to a population crash and other extinctions.

Invasive species

Species not native to an area, introduced often by human transport.

No natural predators to control pop.

Highly competitive for resources

Generalist species are more likely to be invasive

Indicator species

 species that serve as early warnings that an ecosystem is being damaged because they are affected by a change in one or more key abiotic factors in the environment.

Native species

Species that normally live and thrive in a particular ecosystem

Non-native species

Species that migrate into an ecosystem or are deliberately or accidentally introduced into an ecosystem.

Can be beneficial or invasive.

Species evenness

the relative proportion of individuals within the different species in a given area

Species richness

the number of species in a given area

Theory of Island Biogeography

a theory that demonstrates the dual importance of habitat size and distance in determining species richness

primary succession

occurs on surfaces that are initially devoid of soil and has bare rock

secondary succession

occurs in areas that have been disturbed but have not lost their soil

Pioneer Species

ability to colonize new areas rapidly and grow well in full sunshine

Ex. Aspen and cherry trees

Climax Community

Historically described as the final stage of succession.