Living Environment Final Exam Review - Unit 8

Unit 8 Review

ecology

• the study of the interaction between the biotic (living) and abiotic (non-living) factors in the environment

habitat

• the part of the environment to which an organism is best adapted

niche

• the role an organism plays in its environment

• some parts of an organism’s niche include its habitat, trophic level, mating time, location, and behaviors

• two species in an ecosystem trying to fill the same niche will cause competition which usually results in only ONE species occupying a niche at any one time (organisms with similar needs will often divide resources to reduce competition)

community interactions (how organisms interact with each other)

• competition

• nutritional relationships

• symbiosis

• predator-prey relationships

competition

• two or more organisms fight for a limited resource (factor) in the environment

• ex. squirrel and chipmunk compete for food

nutritional relationships

• autotrophs (aka PRODUCERS) can make their own food using PHOTOSYNTHESIS

• heterotrophs (aka CONSUMERS) eat other organisms to obtain food

• ex. animals, fungi, decomposers

types of heterotrophs

• herbivores (primary consumers) - eat plants (land) or algae (water), ex. deer

• carnivores (secondary consumers) - eat other consumers, ex. sharks

• omnivores (primary or secondary) - eat both producers and consumers, ex. black bears

• decomposers (bacteria of decay, fungi) - break down and recycle nutrients back into the environment

symbiosis

• a close relationship between two organisms in which at least one benefits

• three different types:

  • two organisms working together for mutual benefit (mutualism - ex. bee and flower)

  • 1 organism harming another (parasitism - ex. parasite and host)

  • 1 being unaffected (commensalism - ex. shark and remora)

predator-prey relationships

• follow a cyclic pattern of population growth and decline with the prey population peaking slightly before the predator population

• needs to be more prey than predators, otherwise the predators will run out of food

• ex. coyotes and deer

ecological organization

• abiotic factors - non-living things in the environment (ex. rocks, sunlight, temperature, wind, tides, natural disasters)

• biotic factors - living things in the environment (ex. bacteria, fungi, protists, plants, animals)

• levels of organization from least to most complex: organism —> population —> community —> ecosystem —> biosphere

factors needed to maintain a self-sustaining, stable ecosystem

1. producers (to convert light energy into chemical energy) and a constant source of energy (sun)

2. decomposers (got recycle nutrients back into the environment)

3. material cycles (ex. nitrogen cycle, water cycle, carbon-oxygen cycle)

   1. ENERGY DOES NOT CYCLE THROUGH an ecosystem, it is passed from one organism to the next, with energy lost with each new organism in the chain!

population ecology

• a given area can only supply enough resources for a limited number of organisms

• carrying capacity - the number of organisms that a particular environment can sustain/hold

• limiting factors - anything which limits the size of a population

  • abiotic factors (amount of O2, amount of sunlight, amount of water, etc. )

  • predation

  • competition

  • disease (easily spread by overcrowding)

• overpopulation - when population exceeds the carrying capacity (usually results in a large number of organisms dying off until a new balance is reached, leads to fluctuations you see around the carrying capacity)

energy flow in an ecosystem

• the SUN provides all energy for life on Earth

• sun’s energy is stored in the chemical bonds of organic compounds like GLUCOSE through the process of PHOTOSYNTHESIS

• a FOOD CHAIN shows one way that energy can flow through an ecosystem

• a FOOD WEB shows many energy pathways, it is a more accurate representation of a nutritional relationship

• an ENERGY PYRAMID shows that energy gets lost with each step in a food chain

  • only about 10% of energy is passed from one step to the next, this energy is lost as HEAT or as ENERGY USED BY THAT LEVEL FOR THEIR OWN METABOLISM

  • this is why populations of predators typically have FEWER members than populations of their prey, this is called the BIOMASS PYRAMID

  • producers should always be found at the BOTTOM of the pyramid because they have the greatest energy

biodiversity

• refers to the variety of life on earth

• diverse ecosystems (those with many types of species) are more stable than ones that are not diverse

• as habitats are lost and species become extinct, biodiversity is LOST which disrupts ecosystem stability because ecosystems of low diversity are less stable than ecosystems with more diversity and humans use organisms for many things such as food and medicine (by reducing biodiversity we are losing potentially valuable resources)

ecological succession

• the gradual sequence of changes in an ecosystem as one community replaces another due to changes in the biotic and abiotic factors in that environment

• the organisms in each stage of succession CHANGE the environment, allowing new organisms to move in and replace them until a CLIMAX COMMUNITY is reached

climax community

• the stable, mature community that undergoes little change in its members

• determined by the local climate (ex. New York’s climax community is a deciduous forest with hardwood trees that lose their leaves in the winter)

• any temporary disruption of a community will begin the process of succession all over again (ex. if a forest fire kills all of the trees, succession will eventually return the area back to a forest, but it first must pass through all the necessary stages)

human impact on ecosystems

• can be both negative and positive

• the primary reason humans have a negative impact on the environment is because the human population is growing, which places a greater demand on resources such as food, water and space

renewable resources

• resources that can be replaced by natural processes faster than they can be consumed

• ex. solar energy, wind power, hydropower, certain trees/plants (if re-planted)

non-renewable resources

• aka finite resources

• natural resources available in limited amounts that cannot be replaced or are replaced very slowly by natural processes

• ex. fossil fuels; minerals like gold, silver, and iron; coal; oil; natural gas

trade-offs

• an exchange of one thing in return for another to achieve a desired result

• there are no easy solutions to any ecological problem - every solution can have negative consequences

• choosing the “right” action requires weighing the benefits with the risks

human actions that generally have a negative impact on the environment

• development/industrialization

• pollution (air, land, water)

• poor farming practices (leading to soil depletion, desertification)

• overhunting/exploitation of exotic/endangered species

• clear cutting/deforestation

• introduction of foreign species (invasive)

actions being taken by humans to reduce and/or repair damage to the environment

• recycling wastes (paper, plastics, metals, etc.)

• conserving available resources ('“energy smart” appliances bamboo and cork flooring, etc.)

• using cleaner resources (ex. solar and wind power over fossil fuels)

• protection of habitats and endangered species

• use of biological controls instead of pesticides and herbicides

• farming native plants (ex. cocoa in the rainforest)

• planting trees to replace those cut down

• rotating crops or planting cover crops to reduce soil loss

• passing laws to control

specific environmental problems

• acid rain

• ozone depletion

• habitat destruction/deforestation

• loss of biodiversity

• global warming

• imported/invasive specifies

• thermal pollution

• algae blooms/eutrophication

acid rain

• cause: gases produced by burning nitrogen oxides and sulfur oxides in fossil fuels, combines with water in the atmosphere to create acid rain

• negative effect: gets into stream, ponds, rivers, lakes, and lowers the pH which kills plants and animals in the water creating “dead zones”; on land it decreases the pH of the soil which kills plants and disrupts food chains

• what can be done: decrease fossil fuel use by alternative energy resources, gas emissions laws for industries and automobiles, more gas and efficient vehicles

ozone depletion

• cause: CFC’s from aerosols and refrigerants polluting the atmosphere

• negative effect: puts a hole in the ozone layer which protects organisms from the sun’s UV radiation (increases risk of skin cancer, causes DNA mutations in plant and animal tissues)

• what can be done: laws have been put in place to reduce CFC emissions which is slowing the decline in the ozone layer

habitat destruction/deforestation

• cause: increases in human population require more space for homes, roads, food production, etc., more humans = more waste to store and dispose and more pollution and consumption of finite resources

• negative effect: loss of biodiversity as habitats are destroyed and organisms go extinct, disruption of food webs

• what can be done: make laws to protect endangered habitats, reduce, reuse, recycle

loss of biodiversity

• cause: habitat destruction, pollution, poaching/hunting, poor agricultural practices

• negative effect: loss of possible sources of medicine and food, aesthetic loss (not as beautiful), collapse of ecosystems as food webs are disrupted/destroyed

• what can be done: see habitat destruction/deforestation, protect existing “hot spots” of biodiversity, raise awareness/education

global warming (climate change)

• cause: increased use of fossil fuels which causes an increase in CO2 levels in the atmosphere (CO2, CH4 - methane, water vapor, and nitrogen oxides are called “greenhouse gases”)

• negative effect: excess CO2 traps energy from the sun (earth becomes like a giant greenhouse) which results in an increase in average global temperatures (leads to melting of the polar ice caps, changes in weather patterns, loss of biodiversity, etc.)

• what can be done: decrease fossil fuel use, gas emissions laws for industries and automobiles, more gas efficient vehicles, be aware of your “carbon footprint”

imported/invasive species

• cause: intentional or accidental introduction of a species into a NEW environment/habitat in where it is currently not found (ex. zebra mussels, Asian carp, etc.)

• negative effect: competition with native species for a limited resource (native species loses because the new species has no natural predators), disruption of food chains/webs, loss of biodiversity

• what can be done: laws to prevent moving organisms from place to place (country to country), introduction of natural predators (can be problematic), kill the invasive species using chemicals (can harm other organisms in the environment)

thermal pollution

• cause: warm water is released into a lake, stream, or river after certain factories (nuclear power plants and others) use it to cool down their machines, increase in water temp causes a decrease in oxygen in the water

• negative effect: massive fish kills because of the lack of oxygen, plants overgrown as the food chain is disrupted, decomposers increase and remove even more oxygen from the water which creates “dead zones” in the water, could include disposal of radioactive waste

• what can be done: use warm water to heat the factory and recycle the cooled water to cool the machines

algae blooms/eutrophication

• cause: excessive use of fertilizers on lawns, golf courses, and large farms cause nutrients (nitrates and phosphates) to end up in bodies of water which leads to an increase in the growth of algae

• negative effect: overpopulation of algae will cause an increase in decomposers when they die which will lead to a decrease in oxygen which will cause “dead zones” and lead to massive fish kills (this is called EUTROPHICATION), in ponds can lead to ecological succession

• what can be done: decrease use of chemical fertilizers, use phosphate-free soaps and detergents